1.
Wood shaper
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The spindle may be raised and lowered relative to the shapers table, and rotates between 3,000 and 10,000 rpm, with stock running along a vertical fence. Wood shaper cutter heads typically have three blades, and turn at 1/2 to 1/8th the speed of smaller, much less expensive two-bladed bits used on a wood router. Adapters are sold allowing a shaper to drive router bits, a compromise on several levels, as are router tables, cost-saving adaptations of hand-held routers mounted to comparatively light-duty dedicated work tables. Shapers feature between 1.5 and 5 hp belt-driven motors, which run more quietly and smoothly than typically 20,000 to 25,000 rpm direct-drive routers. Speed adjustments are made by relocating the belts on a stepped pulley system. The most common form of wood shaper has a spindle, some have horizontal. Some European models variously combine sliding tablesaws, jointers, planers, Shapers can be adapted to perform specialized cuts employing accessories such as sliding tables, tenon tables, tilting arbor, tenoning hoods, and interchangeable spindles. The standard US spindle shaft is 1¼, with 3/4 on small shapers, most spindles are tall enough to accommodate more than one cutter head, allowing rapid tooling changes by raising or lowering desired heads into position. Additional spindles can be fitted with pre-spaced cutter heads when more are needed for a job than fit on one, the primary safety feature on a wood shaper is a guard mounted above the cutter protecting hands and garments from being drawn into its blades. Jigs, fixtures such as hold-downs, and accessories that include featherboards, also help prevent injury and generally result in better cuts. The starter, or fulcrum, pin is a rod which threads into the table a few inches away from the cutter allowing stock to be fed into it in a freehand cut. In addition to aiding productivity and setting a consistent rate of milling and they may be multi-speed, and employ rubber wheels to feed stock past the cutter head. Wood Shapers - Information and resources about wood shapers, particularly older models
2.
Boring (manufacturing)
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In machining, boring is the process of enlarging a hole that has already been drilled, by means of a single-point cutting tool, for example as in boring a gun barrel or an engine cylinder. Boring is used to greater accuracy of the diameter of a hole. Boring can be viewed as the counterpart to turning, which cuts external diameters. There are various types of boring, the boring bar may be supported on both ends, or it may be supported at one end. Backboring is the process of reaching through a hole and then boring on the back side of the workpiece. The first boring machine tool was invented by John Wilkinson in 1775, boring and turning have abrasive counterparts in internal and external cylindrical grinding. Each process is based on the requirements and parameter values of a particular application. The dimensions between the piece and the bit can be changed about two axes to cut both vertically and horizontally into the internal surface. The cutting tool is usually single point, made of M2 and M3 high-speed steel or P10, a tapered hole can also be made by swiveling the head. Boring machines come in a variety of sizes and styles. Boring operations on small workpieces can be carried out on a lathe while larger workpieces are machined on boring mills, workpieces are commonly 1 to 4 metres in diameter, but can be as large as 20 m. Power requirements can be as much as 200 horsepower, cooling of the bores is done through a hollow passageway through the boring bar where coolant can flow freely. Tungsten-alloy disks are sealed in the bar to counteract vibration and chatter during boring, the control systems can be computer-based, allowing for automation and increased consistency. Because boring is meant to decrease the product tolerances on pre-existing holes, first, large length-to-bore-diameters are not preferred due to cutting tool deflection. Next, through holes are preferred over blind holes, interrupted internal working surfaces—where the cutting tool and surface have discontinuous contact—are preferably avoided. The boring bar is the arm of the machine that holds the cutting tool. Because of the factors just mentioned, deep-hole drilling and deep-hole boring are inherently challenging areas of practice that demand special tooling, nevertheless, technologies have been developed that produce deep holes with impressive accuracy. In most cases involve multiple cutting points, diametrically opposed
3.
Electrical discharge machining
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Material is removed from the workpiece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of the electrodes is called the tool-electrode, or simply the tool or electrode, while the other is called the workpiece-electrode, the process depends upon the tool and workpiece not making actual contact. This phenomenon is the same as the breakdown of a capacitor, as a result, material is removed from the electrodes. Adding new liquid dielectric in the volume is commonly referred to as flushing. Also, after a current flow, the difference of potential between the electrodes is restored to what it was before the breakdown, so that a new liquid dielectric breakdown can occur, the erosive effect of electrical discharges was first noted in 1770 by English physicist Joseph Priestley. Two Russian scientists, B. R. Butinzky and N. I, lazarenko, were tasked in 1943 to investigate ways of preventing the erosion of tungsten electrical contacts due to sparking. They failed in this task but found that the erosion was more precisely controlled if the electrodes were immersed in a dielectric fluid and this led them to invent an EDM machine used for working difficult-to-machine materials such as tungsten. The Lazarenkos machine is known as an R-C-type machine, after the circuit used to charge the electrodes. Simultaneously but independently, an American team, Harold Stark, Victor Harding, initially constructing their machines from feeble electric-etching tools, they were not very successful. But more powerful sparking units, combined with automatic spark repetition, Stark, Harding, and Beavers machines were able to produce 60 sparks per second. Later machines based on their design used vacuum tube circuits that were able to produce thousands of sparks per second, the wire-cut type of machine arose in the 1960s for the purpose of making tools from hardened steel. The tool electrode in wire EDM is simply a wire, to avoid the erosion of material from the wire causing it to break, the wire is wound between two spools so that the active part of the wire is constantly changing. The earliest numerical controlled machines were conversions of punched-tape vertical milling machines, the first commercially available NC machine built as a wire-cut EDM machine was manufactured in the USSR in 1967. Machines that could optically follow lines on a master drawing were developed by David H. Dulebohns group in the 1960s at Andrew Engineering Company for milling and grinding machines, master drawings were later produced by computer numerical controlled plotters for greater accuracy. A wire-cut EDM machine using the CNC drawing plotter and optical line follower techniques was produced in 1974, dulebohn later used the same plotter CNC program to directly control the EDM machine, and the first CNC EDM machine was produced in 1976. Electrical discharge machining is a machining method primarily used for hard metals or those that would be difficult to machine with traditional techniques. EDM typically works with materials that are conductive, although methods for machining insulating ceramics with EDM have also been proposed. EDM can cut intricate contours or cavities in pre-hardened steel without the need for treatment to soften and re-harden them
4.
Machine tool
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A machine tool is a machine for shaping or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformation. Machine tools employ some sort of tool that does the cutting or shaping, all machine tools have some means of constraining the workpiece and provide a guided movement of the parts of the machine. Thus the relative movement between the workpiece and the tool is controlled or constrained by the machine to at least some extent. The precise definition of the machine tool varies among users. While all machine tools are machines that help people to make things, today machine tools are typically powered other than by human muscle, used to make manufactured parts in various ways that include cutting or certain other kinds of deformation. With their inherent precision, machine tools enabled the production of interchangeable parts. In this view of the definition, the term, arising at a time when all tools up till then had been hand tools and this lathe produced screw threads out of wood and employed a true compound slide rest. The mechanical toolpath guidance grew out of various concepts, First is the spindle concept itself. The machine slide, which has many forms, such as dovetail ways, box ways, Machine slides constrain tool or workpiece movement linearly. If a stop is added, the length of the line can also be accurately controlled, tracing, which involves following the contours of a model or template and transferring the resulting motion to the toolpath. Cam operation, which is related in principle to tracing but can be a step or two removed from the traced elements matching the reproduced elements final shape. For example, several cams, no one of which matches the desired output shape. Abstractly programmable toolpath guidance began with mechanical solutions, such as in musical box cams, later, electromechanical solutions and soon electronic solutions were added, leading to numerical control and computer numerical control. The value that machine tools added to these human talents is in the areas of rigidity, accuracy and precision, efficiency, as an example, it is physically possible to make interchangeable screws, bolts, and nuts entirely with freehand toolpaths. But it is practical to make them only with machine tools. In the 1930s, the U. S. National Bureau of Economic Research referenced the definition of a tool as any machine operating by other than hand power which employs a tool to work on metal. The narrowest colloquial sense of the reserves it only for machines that perform metal cutting—in other words. These processes are a type of deformation that produces swarf, thus presses are usually included in the economic definition of machine tools
5.
Tool bit
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A tool bit is a non-rotary cutting tool used in metal lathes, shapers, and planers. Such cutters are often referred to by the set-phrase name of single-point cutting tool. The cutting edge is ground to suit a particular machining operation, the ground tool bit is held rigidly by a tool holder while it is cutting. Back rake is to control the direction of the chip. It also helps counteract the pressure against the tool from the work by pulling the tool into the work. Side Rake along with back rake controls the flow and partly counteracts the resistance of the work to the movement of the cutter. Brass for example requires a back and side rake of 0 degrees while aluminum uses a rake of 35 degrees. Nose Radius makes the finish of the cut smoother as it can overlap the previous cut and eliminate the peaks, having a radius also strengthens the tip, a sharp point being quite fragile. All the other angles are for clearance in order that no part of the tool besides the actual cutting edge can touch the work, the front clearance angle is usually 8 degrees while the side clearance angle is 10-15 degrees and partly depends on the rate of feed expected. The Rake angles on the top of the tool need not be precise in order to cut but to cut efficiently there will be an angle for back. Originally, all tool bits were made of carbon tool steels with the appropriate hardening and tempering. Since the introductions of high-speed steel, sintered carbide, ceramic and diamond cutters, most tool bits today are made of HSS, cobalt steel, or carbide. Carbide, ceramics and diamond, having higher hardness than HSS, because these materials are more expensive and brittler than steel, typically the body of the cutting tool is made of steel, and a small cutting edge made of the harder material is attached. The cutting edge is either screwed or clamped on, or brazed on to a steel shank. Almost all high-performance cutting tools use indexable inserts, there are several reasons for this. First of all, at the very high cutting speeds and feeds supported by these materials, economics are also important, inserts are made symmetrically so that when the first cutting edge is dull they can be rotated, presenting a fresh cutting edge. Some inserts are made so that they can be flipped over. There are many types of inserts, some for roughing, some for finishing, others are made for specialized jobs like cutting threads or grooves
6.
Machining
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Machining is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. Exactly what the part of the definition implies can vary. Machining is a part of the manufacture of metal products, but it can also be used on materials such as wood, plastic, ceramic. A person who specializes in machining is called a machinist, a room, building, or company where machining is done is called a machine shop. Machining can be a business, a hobby, or both, much of modern-day machining is carried out by computer numerical control, in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines. The precise meaning of the term machining has evolved over the past one, in the 18th century, the word machinist simply meant a person who built or repaired machines. This persons work was mostly by hand, using processes such as the carving of wood. At the time, millwrights and builders of new kinds of engines, such as James Watt or John Wilkinson, the noun machine tool and the verb to machine did not yet exist. Around the middle of the 19th century, the words were coined as the concepts that they described evolved into widespread existence. Therefore, during the Machine Age, machining referred to the machining processes, such as turning, boring, drilling, milling, broaching, sawing, shaping, planing, reaming. In current usage, the term machining without qualification usually implies the traditional machining processes, the three principal machining processes are classified as turning, drilling and milling. Other operations falling into miscellaneous categories include shaping, planing, boring, broaching and sawing, turning operations are operations that rotate the workpiece as the primary method of moving metal against the cutting tool. Lathes are the machine tool used in turning. Milling operations are operations in which the tool rotates to bring cutting edges to bear against the workpiece. Milling machines are the machine tool used in milling. Drilling operations are operations in which holes are produced or refined by bringing a rotating cutter with cutting edges at the lower extremity into contact with the workpiece, drilling operations are done primarily in drill presses but sometimes on lathes or mills. Burnishing is an example of a miscellaneous operation, burnishing produces no swarf but can be performed at a lathe, mill, or drill press. An unfinished workpiece requiring machining will need to have some material cut away to create a finished product, a finished product would be a workpiece that meets the specifications set out for that workpiece by engineering drawings or blueprints
7.
Lathe
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Lathes are used in woodturning, metalworking, metal spinning, thermal spraying, parts reclamation, and glass-working. Lathes can be used to shape pottery, the design being the potters wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces, ornamental lathes can produce three-dimensional solids of incredible complexity. The workpiece is held in place by either one or two centers, at least one of which can typically be moved horizontally to accommodate varying workpiece lengths. Other work-holding methods include clamping the work about the axis of rotation using a chuck or collet, or to a faceplate, using clamps or dogs. Examples of objects that can be produced on a lathe include candlestick holders, gun barrels, cue sticks, table legs, bowls, baseball bats, musical instruments, crankshafts, and camshafts. The lathe is an ancient tool, dating at least to ancient Egypt and known to be used in Assyria, the lathe was very important to the Industrial Revolution. It is known as the mother of machine tools, as it was the first machine tool that lead to the invention of other machine tools, the origin of turning dates to around 1300 BCE when the Ancient Egyptians first developed a two-person lathe. One person would turn the work piece with a rope while the other used a sharp tool to cut shapes in the wood. Ancient Rome improved the Egyptian design with the addition of a turning bow, in the Middle Ages a pedal replaced hand-operated turning, allowing a single person to rotate the piece while working with both hands. The pedal was usually connected to a pole, often a straight-grained sapling, the system today is called the spring pole lathe. Spring pole lathes were in use into the early 20th century. An important early lathe in the UK was the boring machine that was installed in 1772 in the Royal Arsenal in Woolwich. It was horse-powered and allowed for the production of more accurate. One of the key characteristics of this machine was that the workpiece was turning as opposed to the tool, henry Maudslay who later developed many improvements to the lathe worked at the Royal Arsenal from 1783 being exposed to this machine in the Verbruggen workshop. During the Industrial Revolution, mechanized power generated by water wheels or steam engines was transmitted to the lathe via line shafting, allowing faster and easier work, metalworking lathes evolved into heavier machines with thicker, more rigid parts. Between the late 19th and mid-20th centuries, individual electric motors at each lathe replaced line shafting as the power source, today manually controlled and CNC lathes coexist in the manufacturing industries. A lathe may or may not have legs, which sit on the floor, a lathe may be small and sit on a workbench or table, not requiring a stand
8.
Helix
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A helix is a type of smooth space curve, i. e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a line called the axis. Examples of helices are coil springs and the handrails of spiral staircases, a filled-in helix – for example, a spiral ramp – is called a helicoid. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices, the word helix comes from the Greek word ἕλιξ, twisted, curved. Helices can be either right-handed or left-handed, handedness is a property of the helix, not of the perspective, a right-handed helix cannot be turned to look like a left-handed one unless it is viewed in a mirror, and vice versa. Most hardware screw threads are right-handed helices, the alpha helix in biology as well as the A and B forms of DNA are also right-handed helices. The Z form of DNA is left-handed, the pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two helices with the axis, differing by a translation along the axis. A conic helix may be defined as a spiral on a conic surface, an example is the Corkscrew roller coaster at Cedar Point amusement park. A circular helix, has constant band curvature and constant torsion, a curve is called a general helix or cylindrical helix if its tangent makes a constant angle with a fixed line in space. A curve is a general helix if and only if the ratio of curvature to torsion is constant, a curve is called a slant helix if its principal normal makes a constant angle with a fixed line in space. It can be constructed by applying a transformation to the frame of a general helix. Some curves found in nature consist of multiple helices of different handedness joined together by transitions known as tendril perversions, in mathematics, a helix is a curve in 3-dimensional space. The following parametrisation in Cartesian coordinates defines a particular helix, Probably the simplest equations for one is x = cos , y = sin , z = t. As the parameter t increases, the point traces a right-handed helix of pitch 2θ and radius 1 about the z-axis, in cylindrical coordinates, the same helix is parametrised by, r =1, θ = t, h = t. A circular helix of radius a and slope b/a is described by the following parametrisation, another way of mathematically constructing a helix is to plot the complex-valued function exi as a function of the real number x. The value of x and the real and imaginary parts of the function value give this plot three real dimensions, except for rotations, translations, and changes of scale, all right-handed helices are equivalent to the helix defined above. The equivalent left-handed helix can be constructed in a number of ways, in music, pitch space is often modeled with helices or double helices, most often extending out of a circle such as the circle of fifths, so as to represent octave equivalency
9.
North America
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North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16. 5% of the land area. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7. 5% of the worlds population, North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago, the Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended with the migrations and the arrival of European settlers during the Age of Discovery. Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists, indigenous peoples, African slaves and their descendants, European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south. Because of the history of colonialism, most North Americans speak English, Spanish or French, the Americas are usually accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass previously unknown by Europeans. In 1507, Waldseemüller produced a map, in which he placed the word America on the continent of South America. He explained the rationale for the name in the accompanying book Cosmographiae Introductio, for Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespuccis name, but in its feminine form America, following the examples of Europa, Asia and Africa. Later, other mapmakers extended the name America to the continent, In 1538. Some argue that the convention is to use the surname for naming discoveries except in the case of royalty, a minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of Amairick. Another is that the name is rooted in a Native American language, the term North America maintains various definitions in accordance with location and context. In Canadian English, North America may be used to refer to the United States, alternatively, usage sometimes includes Greenland and Mexico, as well as offshore islands
10.
United Kingdom
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The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe. Lying off the north-western coast of the European mainland, the United Kingdom includes the island of Great Britain, Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state—the Republic of Ireland. The Irish Sea lies between Great Britain and Ireland, with an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world and the 11th-largest in Europe. It is also the 21st-most populous country, with an estimated 65.1 million inhabitants, together, this makes it the fourth-most densely populated country in the European Union. The United Kingdom is a monarchy with a parliamentary system of governance. The monarch is Queen Elizabeth II, who has reigned since 6 February 1952, other major urban areas in the United Kingdom include the regions of Birmingham, Leeds, Glasgow, Liverpool and Manchester. The United Kingdom consists of four countries—England, Scotland, Wales, the last three have devolved administrations, each with varying powers, based in their capitals, Edinburgh, Cardiff and Belfast, respectively. The relationships among the countries of the UK have changed over time, Wales was annexed by the Kingdom of England under the Laws in Wales Acts 1535 and 1542. A treaty between England and Scotland resulted in 1707 in a unified Kingdom of Great Britain, which merged in 1801 with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain, there are fourteen British Overseas Territories. These are the remnants of the British Empire which, at its height in the 1920s, British influence can be observed in the language, culture and legal systems of many of its former colonies. The United Kingdom is a country and has the worlds fifth-largest economy by nominal GDP. The UK is considered to have an economy and is categorised as very high in the Human Development Index. It was the worlds first industrialised country and the worlds foremost power during the 19th, the UK remains a great power with considerable economic, cultural, military, scientific and political influence internationally. It is a nuclear weapons state and its military expenditure ranks fourth or fifth in the world. The UK has been a permanent member of the United Nations Security Council since its first session in 1946 and it has been a leading member state of the EU and its predecessor, the European Economic Community, since 1973. However, on 23 June 2016, a referendum on the UKs membership of the EU resulted in a decision to leave. The Acts of Union 1800 united the Kingdom of Great Britain, Scotland, Wales and Northern Ireland have devolved self-government
11.
Planer (metalworking)
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A planer is a type of metalworking machine tool that uses linear relative motion between the workpiece and a single-point cutting tool to cut the work piece. A planer is similar to a shaper, but larger, and with workpiece moving, watch video, Demonstration of metal planer on YouTube The most common applications of planers and shapers are linear-toolpath ones, such as, Generating accurate flat surfaces. It is even possible to do work that might now be done by wire EDM in some cases, starting from a drilled or cored hole, a planer with a boring-bar type tool can cut internal features that dont lend themselves to milling or boring. Although the archetypal toolpath of a planer is linear, helical cutting can be accomplished by coupling the tables linear motion to simultaneous rotation, the helical planing idea is similar to both helical milling and single-point screw cutting. Planers and shapers are now obsolescent, because machine tools have mostly eclipsed them as the tools of choice for doing such work. However, they have not yet disappeared from the metalworking world, planers are used by smaller tool and die shops within larger production facilities to maintain and repair large stamping dies and plastic injection molds. There are two types of planers for metal, double-housing and open-side, the double-housing variety has vertical supports on both sides of its long bed, the open-side variety has a vertical support on only one side, allowing the workpiece to extend beyond the bed. Metal planers can vary in size from a size of 30×72 to 20×62. Early planing ideas are known to have been underway in France in the 1750s, in the late 1810s, a variety of pioneers in various British shops developed the planer into what we today would call a machine tool. The exact details have been contentious and will never be known. Roe provides a chapter that tells the story as thoroughly as he was able to discover it. Roe, Joseph Wickham, English and American Tool Builders, New Haven, Connecticut, Yale University Press, reprinted by McGraw-Hill, New York and London,1926, and by Lindsay Publications, Inc. YouTube video of a planer in action Another YouTube video of a planer in action
12.
Crank (mechanism)
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A crank is an arm attached at a right angle to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to convert circular motion into reciprocating motion, or vice versa, the arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, the end of the rod attached to the crank moves in a circular motion, while the other end is usually constrained to move in a linear sliding motion. The term often refers to a crank which is used to manually turn an axle, as in a bicycle crankset or a brace. In this case a persons arm or leg serves as the connecting rod, there is usually a bar perpendicular to the other end of the arm, often with a freely rotatable handle or pedal attached. Familiar examples include, Mechanical pencil sharpener Fishing reel and other reels for cables, wires, ropes, manually operated car window The carpenters brace is a compound crank. The crank set that drives a handcycle through its handles, the crankset that drives a bicycle via the pedals. Treadle sewing machine Almost all reciprocating engines use cranks to transform the motion of the pistons into rotary motion. The cranks are incorporated into a crankshaft, the displacement of the end of the connecting rod is approximately proportional to the cosine of the angle of rotation of the crank, when it is measured from top dead center. The mechanical advantage of a crank, the ratio between the force on the rod and the torque on the shaft, varies throughout the cranks cycle. The relationship between the two is approximately, τ = F r sin where τ is the torque and F is the force on the connecting rod. But in reality, the torque is maximum at crank angle of less than α = 90° from TDC for a force on the piston. One way to calculate this angle is to find out when the Connecting rod smallend speed becomes the fastest in downward direction given a steady crank rotational velocity. 17615° after TDC. Then, using the sine law, it is found that the crank to connecting rod angle is 88. 21738°. When the crank is driven by the rod, a problem arises when the crank is at top dead centre or bottom dead centre. At these points in the cycle, a force on the connecting rod causes no torque on the crank. Therefore, if the crank is stationary and happens to be at one of two points, it cannot be started moving by the connecting rod. The eccentrically mounted handle of the rotary handmill which appeared in 5th century BC Celtiberian Spain, a Roman iron crank of yet unknown purpose dating to the 2nd century AD was excavated in Augusta Raurica, Switzerland
13.
Hydraulic cylinder
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A hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment, manufacturing machinery, Hydraulic cylinders get their power from pressurized hydraulic fluid, which is typically oil. The hydraulic cylinder consists of a barrel, in which a piston connected to a piston rod moves back. The barrel is closed on one end by the cylinder bottom, the piston has sliding rings and seals. The piston divides the inside of the cylinder into two chambers, the chamber and the piston rod side chamber. Flanges, trunnions, clevises, Lugs are common cylinder mounting options, the piston rod also has mounting attachments to connect the cylinder to the object or machine component that it is pushing / pulling. A hydraulic cylinder is the actuator or motor side of this system, the generator side of the hydraulic system is the hydraulic pump which brings in a fixed or regulated flow of oil to the hydraulic cylinder, to move the piston. The piston pushes the oil in the chamber back to the reservoir. The cylinder rod reduces the area of the piston and reduces the force that can be applied for the retraction stroke. For double-acting, double-rod cylinders, when the surface area is equally covered by a rod of equal size on both sides of the head, there is no force difference. Such cylinders typically have their cylinder body affixed to a stationary mount, a hydraulic cylinder consists of the following parts, The main function of cylinder body is to hold cylinder pressure. The cylinder barrel is made from a seamless tube. The cylinder barrel is ground and/or honed internally with a surface finish of 4 to 16 microinch. The piston reciprocates in the cylinder, the main function of the cap is to enclose the pressure chamber at one end. The cap is connected to the body by means of welding, threading, bolts, caps also perform as cylinder mounting components. Cap size is determined based on the bending stress, a static seal / o-ring is used in between cap and barrel. The main function of the head is to enclose the chamber from the other end. The head contains an integrated rod sealing arrangement or the option to accept a seal gland, the head is connected to the body by means of threading, bolts, or tie rod
14.
Rotary table
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A rotary table is a precision work positioning device used in metalworking. It enables the operator to drill or cut work at exact intervals around a fixed axis, a rotary fixture used in this fashion is more appropriately called a dividing head. The table shown is a manually operated type, powered tables under the control of CNC machines are now available, and provide a fourth axis to CNC milling machines. Rotary tables are made with a base, which has provision for clamping onto another table or fixture. The actual table is a disc to which the work piece is clamped. This disc can rotate freely, for indexing, or under the control of a worm, high precision tables are driven by backlash compensating duplex worms. The ratio between worm and table is generally 40,1,72,1 or 90,1 and this is for ease of use when indexing plates are available. A graduated dial and, often, a vernier scale enable the operator to position the table, a through hole is usually machined into the table. Most commonly, this hole is machined to admit a Morse taper center or fixture, Rotary tables are most commonly mounted flat, with the table rotating around a vertical axis, in the same plane as the cutter of a vertical milling machine. An alternate setup is to mount the rotary table on its end, in this configuration a tailstock can also be used, thus holding the workpiece between centers. With the table mounted on a table, the workpiece is accurately centered on the rotary tables axis. All three axes are thus coaxial, from this point, the secondary table can be offset in either the X or Y direction to set the cutter the desired distance from the workpieces center. This allows concentric machining operations on the workpiece, placing the workpiece eccentrically a set distance from the center permits more complex curves to be cut. This enables an arc to be cut at any place on the part, Rotary tables have many applications, including being used in the manufacture and inspection process of important elements in aerospace, automation and scientific industries. The use of rotary tables stretches as far as the film and animation industry, being used to obtain accuracy and precision in filming and photography. Metrology – the range of tables that are used for metrology include mechanical and air bearings, full positioning and indexing tables. Machining – rotary tables can be used in the machining of components in heavy duty industries, scientific – some rotary tables are designed for the scientific community and are capable of operation in vacuum. The internal workings of a CNC rotary table Overview of a rotary table Rotary table construction UK Provider of Precision Rotary Tables for Inspection Systems
15.
Screw (simple machine)
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A screw is a mechanism that converts rotational motion to linear motion, and a torque to a linear force. It is one of the six simple machines. The most common form consists of a shaft with helical grooves or ridges called threads around the outside. The screw passes through a hole in another object or medium, when the shaft of the screw is rotated relative to the stationary threads, the screw moves along its axis relative to the medium surrounding it, for example rotating a wood screw forces it into wood. In screw mechanisms, either the shaft can rotate through a threaded hole in a stationary object. Geometrically, a screw can be viewed as an inclined plane wrapped around a cylinder. Like the other simple machines a screw can amplify force, a rotational force on the shaft can exert a large axial force on a load. The smaller the pitch, the distance between the threads, the greater the mechanical advantage, the ratio of output to input force. Screws are widely used in threaded fasteners to hold objects together, other mechanisms that use the same principle, also called screws, dont necessarily have a shaft or threads. For example, a corkscrew is a rod with a sharp point. The common principle of all screws is that a rotating helix can cause linear motion, the screw was one of the last of the simple machines to be invented. It first appeared in ancient Greece, and by the first century BC was used in the form of the press and the Archimedes screw. Greek philosopher Archytas of Tarrentum was said by the Greeks to have invented the screw, the Greek philosopher Archimedes is credited with inventing the Archimedes screw water pump around 234 BC, although there is evidence it may have come from Egypt. Archimedes was first to study the screw as a machine, so he is considered the inventor of the screw. Greek philosophers defined the screw as one of the simple machines, because they had to be laboriously cut by hand, screws were only used as linkages in a few machines in the ancient world. Screw fasteners only began to be used in the 15th century in clocks, the screw was also apparently applied to drilling and moving materials around this time, when images of augers and drills began to appear in European paintings. The complete dynamic theory of machines, including the screw, was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche. The fineness or coarseness of a screws threads are defined by two related quantities, The lead is defined as the axial distance the screw travels in one complete revolution of the shaft
16.
Scotch yoke
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The Scotch yoke is a reciprocating motion mechanism, converting the linear motion of a slider into rotational motion, or vice versa. The piston or other reciprocating part is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part, the location of the piston versus time is a sine wave of constant amplitude, and constant frequency given a constant rotational speed. This setup is most commonly used in control valve actuators in high-pressure oil, although not a common metalworking machine nowadays, crude shapers can use Scotch yokes. Almost all those use a Whitworth linkage, which gives a slow speed forward cutting stroke and it has been used in various internal combustion engines, such as the Bourke engine, SyTech engine, and many hot air engines and steam engines. The term scotch yoke continues to be used when the slot in the yoke is shorter than the diameter of the circle made by the crank pin, for example, the side rods of a locomotive may have scotch yokes to permit vertical motion of intermediate driving axles. Under ideal engineering conditions, force is applied directly in the line of travel of the assembly, the sinusoidal motion, cosinusoidal velocity, and sinusoidal acceleration result in smoother operation. The higher percentage of time spent at top dead centre improves theoretical engine efficiency of constant volume combustion cycles, the Scotch yoke is not used in most internal combustion engines because of the rapid wear of the slot in the yoke caused by sliding friction and high contact pressures. This is mitigated by a block between the crank and the slot in the piston rod. Also, increased heat loss during combustion due to extended dwell at top dead centre offsets any constant volume combustion improvements in real engines. In an engine application, less percent of the time is spent at bottom dead centre when compared to a piston and crankshaft mechanism. Experiments have shown that extended dwell time does not work well with constant volume combustion Otto cycle engines, gains might be more apparent in Otto cycle engines using a stratified direct injection cycle to reduce heat losses. An improved Scotch yoke, with a means of absorbing sideways thrust, was patented in 1978 by William L. Carlson, brock Institute for Advanced Studies, Scotch Yoke Comparing Simple Crank/Slider and Scotch Yoke Mechanisms by Fred Klingener, The Wolfram Demonstrations Project, Active demo
17.
Pulley
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A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable, supporting shell is referred to as a block. A pulley may also be called a sheave or drum and may have a groove or grooves between two flanges around its circumference. The drive element of a system can be a rope, cable, belt. Hero of Alexandria identified the pulley as one of six simple machines used to lift weights, pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are also assembled as part of belt and chain drives in order to power from one rotating shaft to another. A set of pulleys assembled so that they rotate independently on the axle from a block. Two blocks with an attached to one of the blocks. A block and tackle is assembled so one block is attached to fixed mounting point, the ideal mechanical advantage of the block and tackle is equal to the number of parts of the rope that support the moving block. This system is included in the list of simple machines identified by Renaissance scientists, if the rope and pulley system does not dissipate or store energy, then its mechanical advantage is the number of parts of the rope that act on the load. This can be shown as follows, consider the set of pulleys that form the moving block and the parts of the rope that support this block. If there are p of these parts of the supporting the load W. This means the force on the rope is T=W/p. Thus, the block and tackle reduces the force by the factor p. The simplest theory of operation for a pulley system assumes that the pulleys and lines are weightless, and it is also assumed that the lines do not stretch. In equilibrium, the forces on the block must sum to zero. In addition the tension in the rope must be the same for each of its parts and this means that the two parts of the rope supporting the moving block must each support half the load. These are different types of systems, Fixed, A fixed pulley has an axle mounted in bearings attached to a supporting structure. A fixed pulley changes the direction of the force on a rope or belt that moves along its circumference, mechanical advantage is gained by combining a fixed pulley with a movable pulley or another fixed pulley of a different diameter
18.
Gear
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A gear or cogwheel is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part to transmit torque. Geared devices can change the speed, torque, and direction of a power source, Gears almost always produce a change in torque, creating a mechanical advantage, through their gear ratio, and thus may be considered a simple machine. The teeth on the two meshing gears all have the same shape, two or more meshing gears, working in a sequence, are called a gear train or a transmission. A gear can mesh with a linear toothed part, called a rack, the gears in a transmission are analogous to the wheels in a crossed, belt pulley system. An advantage of gears is that the teeth of a gear prevent slippage, in transmissions with multiple gear ratios—such as bicycles, motorcycles, and cars—the term gear as in first gear refers to a gear ratio rather than an actual physical gear. The term describes similar devices, even when the ratio is continuous rather than discrete, or when the device does not actually contain gears. Early examples of gears date from the 4th century BC in China, examples of further development include, Ma Jun used gears as part of a south-pointing chariot. The Antikythera mechanism is an example of an early and intricate geared device. Its time of construction is now estimated between 150 and 100 BC, the water-powered grain-mill, the water-powered saw mill, fulling mill, and other applications of watermill often used gears. The first mechanical clocks were built in AD725, the 1386 Salisbury cathedral clock may be the worlds oldest working mechanical clock. The definite ratio that teeth give gears provides an advantage over other drives in precision machines such as watches that depend upon an exact velocity ratio, an external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, a gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, a gear is one with the pitch angle exceeding 90 degrees. Internal gears do not cause output shaft direction reversal, spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with teeth projecting radially, though the teeth are not straight-sided, the edge of each tooth is straight and aligned parallel to the axis of rotation. These gears mesh together correctly only if fitted to parallel shafts, No axial thrust is created by the tooth loads. Spur gears are excellent at moderate speeds but tend to be noisy at high speeds, helical or dry fixed gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, since the gear is curved, this angling makes the tooth shape a segment of a helix
19.
Broaching (metalworking)
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Broaching is a machining process that uses a toothed tool, called a broach, to remove material. There are two types of broaching, linear and rotary. In linear broaching, which is the common process, the broach is run linearly against a surface of the workpiece to effect the cut. Linear broaches are used in a machine, which is also sometimes shortened to broach. In rotary broaching, the broach is rotated and pressed into the workpiece to cut an axis symmetric shape, a rotary broach is used in a lathe or screw machine. In both processes the cut is performed in one pass of the broach, which makes it very efficient, Broaching is used when precision machining is required, especially for odd shapes. Commonly machined surfaces include circular and non-circular holes, splines, keyways, typical workpieces include small to medium-sized castings, forgings, screw machine parts, and stampings. Even though broaches can be expensive, broaching is usually favored over other processes used for high-quantity production runs. Broaches are shaped similar to a saw, except the height of the teeth increases over the length of the tool, moreover, the broach contains three distinct sections, one for roughing, another for semi-finishing, and the final one for finishing. Broaching is a machining process because it has the feed built into the tool. The profile of the surface is always the inverse of the profile of the broach. The rise per tooth, also known as the step or feed per tooth, determines the amount of material removed, the broach can be moved relative to the workpiece or vice versa. Because all of the features are built into the broach no complex motion or skilled labor is required to use it. A broach is effectively a collection of single-point cutting tools arrayed in sequence, cutting one after the other, the process depends on the type of broaching being performed. Surface broaching is very simple as either the workpiece is moved against a stationary surface broach, the process begins by clamping the workpiece into a special holding fixture, called a workholder, which mounts in the broaching machine. The broaching machine elevator, which is the part of the machine moves the broach above the workholder. Once through, the broaching machines puller, essentially a hook, the elevator then releases the top of the pilot and the puller pulls the broach through the workpiece completely. The workpiece is then removed from the machine and the broach is raised back up to reengage with the elevator, the broach usually only moves linearly, but sometimes it is also rotated to create a spiral spline or gun-barrel rifling
20.
Blind hole
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A blind hole refers to a hole that is reamed, drilled, or milled to a specified depth without breaking through to the other side of the workpiece. The etymology is that it is not possible to see through a blind hole, other types of holes also include through holes, and clearance holes. In this instance blind may also refer to any feature that is taken to a specific depth, single-pointing inside a blind hole, like boring inside one, is inherently more challenging than doing so in a through hole. This was especially true in the era when manual machining was the method of control. Today, CNC makes these tasks less stressful, but nevertheless still more challenging than with through holes, helical interpolation, where the workpiece remains stationary and CNC control moves a milling cutter in the correct helical path for a given thread, milling the thread. Today many CNC milling machines can run such a thread milling cycle, a video of thread milling with a single-form cutting tool
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Samuel Bentham
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Sir Samuel Bentham was a noted English mechanical engineer and naval architect credited with numerous innovations, particularly related to naval architecture, including weapons. He was the surviving sibling of philosopher Jeremy Bentham, with whom he had a close bond. Samuel Bentham was one of two surviving siblings of Jeremiah Bentham and his father was an attorney, and his older brother was the philosopher Jeremy Bentham, five other siblings having died in infancy or early childhood, and their mother dying in 1766. At the age of 14, Bentham was apprenticed to a shipwright at Woolwich Dockyard, serving there and at Chatham Dockyard, before completing his 7-year training at the Naval Academy in Portsmouth. In 1780 he moved to Russia, where he was employed in the service of Prince Potemkin, initially hired as a shipbuilder, he soon discovered other opportunities to use his talents as an engineer and inventor, constructing industrial machinery and experimenting with steel production. He also designed and constructed many novel inventions, including an amphibious vessel and an articulated barge built for Catherine the Great, and the first Panopticon. He was also decorated for his part in a victory in the war against the Turks. Back in Europe, he campaigned for the introduction of watertight compartments, Samuel returned to England in 1791, and for the next few years was involved with his brother Jeremy in trying to promote the Panopticon scheme and he designed machinery for use in it. It was during this period that he met his wife, Mary Sophia Fordyce, the daughter of Scottish doctor and scientist George Fordyce. The two were married in October 1796, in March 1796 Bentham was appointed Inspector General of Naval Works, responsible for the maintaining and improving the Royal dockyards, a post which involved a lot of travel. He produced a great many suggestions for improvements, which included the introduction of power to the dockyards. However, his superiors at the Navy Board were resistant to change, Bentham is credited with helping to revolutionise the production of the wooden pulley blocks used in ships rigging, devising woodworking machinery to improve production efficiency. Benthams 1793 patent for woodworking machinery has been called one of the most remarkable patents ever issued by the British Patent Office, marc Isambard Brunel had independently conceived designs for mortising and boring machines, which he showed to Bentham, who recognized the superiority of Brunels designs. Henry Maudslay, the mechanic who built the machines, became a prominent machine tool builder, the Portsmouth Block Mills marked the arrival of mass production techniques in British manufacturing. Samuels mission for the British government in Russia was blocked by constant obstacles, during this time he supervised the construction of a Panopticon School of Arts on the banks of the Okhta River in St. Petersburg, the design which he had first conceived while in Krichev in 1786. The building was destroyed by fire and is known from drawings. Bentham also designed a full cast-iron nine-arch bridge for the Butterly company, for Vauxhall Bridge in London, the design was eventually abandoned after doubts about its quality, in favour of a cast iron arches on masonry piers design by James Walker, which was completed in May 1813. In 1814, he and his family relocated to the south of France, the Bentham family travelled a great deal in France before settling in 1820 at the Château de Restinclières, in the région of Languedoc-Roussillon
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James Nasmyth
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James Hall Nasmyth was a Scottish engineer, artist and inventor famous for his development of the steam hammer. He was the co-founder of Nasmyth, Gaskell and Company manufacturers of machine tools and he retired at the age of 48, and moved to Penshurst, Kent where he developed his hobbies of astronomy and photography. James Nasmyth was born at 47 York Place, Edinburgh where his father Alexander Nasmyth was a landscape, one of Alexanders hobbies was mechanics and he employed nearly all his spare time in his workshop where he encouraged his youngest son to work with him in all sorts of materials. James was sent to the Royal High School where he had as a friend, Jimmy Patterson, being already interested in mechanics he spent much of his time at the foundry and there he gradually learned to work and turn in wood, brass, iron, and steel. In 1820 he left the High School and again made use of his fathers workshop where at the age of 17. From 1821 to 1826, Nasmyth regularly attended the Edinburgh School of Arts, in 1828 he made a complete steam carriage that was capable of running a mile carrying 8 passengers. This accomplishment increased his desire to become a mechanical engineer and he had heard of the fame of Henry Maudslays workshop and resolved to get employment there, unfortunately his father could not afford to place him as an apprentice at Maudslays works. In May 1829 Nasmyth visited Maudslay in London, and after showing him his work was engaged as an assistant workman at 10 shillings a week, unfortunately, Maudslay died two years later, whereupon Nasmyth was taken on by Maudslays partner as a draughtsman. When Nasmyth was 23 years old, having saved the sum of ₤69 and he rented a factory flat 130 feet long by 27 feet wide at an old Cotton Mill on Dale Street, Manchester. The premises were constructed adjacent to the Liverpool and Manchester Railway, in March 1838 James was making a journey by coach from Sheffield to York in a snowstorm, when he spied some ironwork furnaces in the distance. The coachman informed him that they were managed by a Mr. Hartop who was one of his customers and he immediately got off the coach and headed for the furnaces through the deep snow. He found Mr. Hartop at his house, and was invited to stay the night and that evening he met Hartops family and was immediately smitten by his 21-year-old daughter, Anne. A decisive man, the day he told her of his feelings and intentions. He then communicated the same to her parents, and told them his prospects and they were married two years later, on 16 June 1840 in Wentworth. Up to 1843, Nasmyth, Gaskell & Co. concentrated on producing a range of machine tools in large numbers. By 1856, Nasmyth had built 236 shaping machines, in 1840 he began to receive orders from the newly opened railways which were beginning to cover the country, for locomotives. Nasmyth thought the matter over and seeing the obvious defects of the tilt-hammer sketched out his idea for the first steam hammer and he kept his ideas for new devices, mostly in drawings, in a Scheme Book which he freely showed to his foreign customers. However, the Schneiders hesitated to build Bourdons radical new machine, Bourdon and Eugène Schneider visited the Nasmyth works in England in the middle of 1840, where they were shown Nasmyths sketch
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Numerical control
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Computer numerical control is the automation of machine tools by means of computers executing pre-programmed sequences of machine control commands. This is in contrast to machines that are controlled by hand wheels or levers. In modern CNC systems, the design of a mechanical part, the parts mechanical dimensions are defined using computer-aided design software, and then translated into manufacturing directives by computer-aided manufacturing software. The resulting directives are transformed into the specific commands necessary for a machine to produce the component. Since any particular component might require the use of a number of different tools – drills, saws, in other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design. The first NC machines were built in the 1940s and 1950s and these early servomechanisms were rapidly augmented with analog and digital computers, creating the modern CNC machine tools that have revolutionized the machining processes. Motion is controlled along multiple axes, normally at least two, and a spindle that moves in the Z. The position of the tool is driven by direct-drive stepper motor or servo motors in order to provide highly accurate movements, or in older designs, open-loop control works as long as the forces are kept small enough and speeds are not too great. On commercial metalworking machines, closed loop controls are standard and required in order to provide the accuracy, speed, as the controller hardware evolved, the mills themselves also evolved. Most new CNC systems built today are 100% electronically controlled, cNC-like systems are now used for any process that can be described as a series of movements and operations. CNC mills use computer controls to cut different materials and they are able to translate programs consisting of specific numbers and letters to move the spindle to various locations and depths. Many use G-code, which is a programming language that many CNC machines understand. These proprietary languages, while often simpler than G-code, are not transferable to other machines, CNC mills have many functions including face milling, shoulder milling, tapping, drilling and some even offer turning. Standard linear CNC mills are limited to 3 axis, but others may also have one or more rotational axes, today, CNC mills can have 4 to 6 axes. Lathes are machines that cut workpieces while they are rotated, CNC lathes are able to make fast, precision cuts, generally using indexable tools and drills. They are particularly effective for complicated programs designed to make parts that would be infeasible to make on manual lathes, CNC lathes have similar control specifications to CNC mills and can often read G-code as well as the manufacturers proprietary programming language. CNC lathes generally have two axes, but newer models have more axes, allowing for more advanced jobs to be machined, plasma cutting involves cutting a material using a plasma torch
24.
Milling (machining)
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Pocket milling has been regarded as one of the most widely used operations in machining. It is extensively used in aerospace and shipyard industries, in pocket milling the material inside an arbitrarily closed boundary on a flat surface of a work piece is removed to a fixed depth. Generally flat bottom end mills are used for pocket milling, firstly roughing operation is done to remove the bulk of material and then the pocket is finished by a finish end mill. Most of the milling operations can be taken care of by 2.5 axis CNC milling. This type of control can machine up to 80% of all mechanical parts. Since the importance of pocket milling is very relevant, therefore effective pocketing approaches can result in reduction in machining time, NC pocket milling can be carried out mainly by two tool paths, viz. linear and non-linear. In this approach, the movement is unidirectional. Zig-zag and zig tool paths are the examples of linear tool path, in zig-zag milling, material is removed both in forward and backward paths. In this case, cutting is done both with and against the rotation of the spindle and this reduces the machining time but increases machine chatter and tool wear. In zig milling, the tool moves only in one direction, the tool has to be lifted and retracted after each cut, due to which machining time increases. However, in case of zig milling surface quality is better, in this approach, tool movement is multi-directional. One example of non-linear tool path is contour-parallel tool path, in this approach, the required pocket boundary is used to derive the tool path. In this case the cutter is always in contact with the work material, hence the idle time spent in positioning and retracting the tool is avoided. For large-scale material removal, contour-parallel tool path is used because it can be consistently used with up-cut or down-cut method during the entire process. There are three different approaches that fall into the category of contour-parallel tool path generation and they are, In pair-wise intersection approach, the boundary of the pocket is brought inwards in steps, The offset segments will intersect at concave corners. To obtain the required contour, these intersections are to be trimmed off, on the other hand, in case of convex corner, the offset segments are extended and thereby connected to make the contour. These operations viz. offsetting, trimming and extending are repeatedly done to cover the entire machining volume with sufficient layer of profiles, in voronoi diagram approach, the pocket boundary is segmented and vornoi diagram is constructed for the entire pocket boundary. These vornoi diagrams are used for generating the tool path for machining and this method is considered to be more efficient and robust
25.
Grinding machine
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A grinding machine, often shortened to grinder, is any of various power tools or machine tools used for grinding, which is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheels surface cuts a small chip from the workpiece via shear deformation, grinding is used to finish workpieces that must show high surface quality and high accuracy of shape and dimension. As the accuracy in dimensions in grinding is of the order of 0.000025 mm, in most applications it tends to be an operation and removes comparatively little metal. However, there are some roughing applications in which grinding removes high volumes of metal quite rapidly, thus, grinding is a diverse field. The grinding machine consists of a bed with a fixture to guide and hold the piece. The speed is determined by the diameter and manufacturer’s rating. The grinding head can travel across a fixed work piece, or the piece can be moved while the grind head stays in a fixed position. Fine control of the head or table position is possible using a vernier calibrated hand wheel. Grinding machines remove material from the piece by abrasion, which can generate substantial amounts of heat. To cool the work piece so that it does not overheat and go outside its tolerance, the coolant also benefits the machinist as the heat generated may cause burns. These machines include the, Belt grinder, which is used as a machining method to process metals and other materials. Belt grinding is a versatile process suitable for all kind of applications, including finishing, deburring, bench grinder, which usually has two wheels of different grain sizes for roughing and finishing operations and is secured to a workbench or floor stand. Its uses include shaping tool bits or various tools that need to be made or repaired, cylindrical grinder, which includes both the types that use centers and the centerless types. A cylindrical grinder may have multiple grinding wheels, the workpiece is rotated and fed past the wheel to form a cylinder. It is used to make precision rods, tubes, bearing races, bushings, the most common surface grinders have a grinding wheel rotating on a horizontal axis cutting around the circumference of the grinding wheel. This type of machine removes large amounts of material and grinds flat surfaces with noted spiral grind marks and it can also be used to make and sharpen metal stamping die sets, flat shear blades, fixture bases or any flat and parallel surfaces. Surface grinders can be operated or have CNC controls. Tool and cutter grinder, which usually can perform the function of the drill bit grinder
26.
Maintenance, repair and operations
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Maintenance, repair, and operations involves fixing any sort of mechanical, plumbing, or electrical device should it become out of order or broken. In the former case it may be an operation within a larger organization or smaller operation. The former of these represents a closed loop supply chain and usually has the scope of maintenance, repair, the latter of the categorisations is an open loop supply chain and is typified by refurbishment and remanufacture. The main characteristic of the loop system is that the demand for a product is matched with the supply of a used product. Neglecting asset write-offs and exceptional activities the total population of the product between the customer and the service provider remains constant, for material – all action taken to retain material in a serviceable condition or to restore it to serviceability. It includes inspection, testing, servicing, classification as to serviceability, repair, rebuilding, for material – all supply and repair action taken to keep a force in condition to carry out its mission. For material – the routine recurring work required to keep a facility in such condition that it may be used, at its original or designed capacity. Manufacturers and industrial-supply companies often refer to MRO as opposed to original equipment manufacturer, OEM includes any activity related to the direct manufacture of goods, where MRO refers to any maintenance, repair or overhaul activity to keep a manufacturing plant or facility running. Maintenance is strictly connected to the stage of ideation, in which the concept of maintainability must be included, overhaul extends to the concept of improving performance over and above original design specification. Corrective maintenance where equipment is repaired or replaced after wear, malfunction or break down, preventive maintenance is maintenance performed with the intent of avoiding failures, safety violations, unnecessary production costs and losses, and to conserve original materials of fabrication. The effectiveness of a maintenance schedule depends on the RCM analysis which it was based on
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Retro style
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Retro style is style that is consciously derivative or imitative of trends, music, modes, fashions, or attitudes of the recent past. The term retro has been in use since the 1960s to describe on the one hand new artifacts that self-consciously refer to particular modes, motifs, techniques, but on the other hand, many people use the term to categorise styles that have been created in the past. Retro style refers to new things that display characteristics of the past and it is mostly the recent past that retro seeks to recapitulate, focusing on the products, fashions and artistic styles produced since the Industrial Revolution, of Modernity. The English word retro derives from the Latin prefix retro, meaning backwards, in France, the word rétro, an abbreviation for rétrospectif, gained cultural currency with reevaluations of Charles de Gaulle and Frances role in World War II. The French mode rétro of the 1970s reappraised in film and novels the conduct of French civilians during the Nazi occupation, the term rétro was soon applied to nostalgic French fashions that recalled the same period. Shortly thereafter it was introduced into English by the fashion and culture press, in Simulacra and Simulation, French theorist Jean Baudrillard describes retro as a demythologization of the past, distancing the present from the big ideas that drove the modern age. Most commonly retro is used to describe objects and attitudes from the recent past that no longer seem modern and it suggests a fundamental shift in the way we relate to the past. The concept of nostalgia is linked to retro, but the desire for things. Retro shows nostalgia with a dose of cynicism and detachment, the desire to capture something from the past and evoke nostalgia is fuelled by dissatisfaction with the present. Retro can be applied to things and artifacts, for example, forms of technological obsolescence and also the resurrection of old computer games. Since the 1980s the implications of the word ‘retro’ have been expanding in the application to different media, several fields have adopted the term retro from the design world. Thus next to design artefacts like objects, graphic design, fashion and interior design, ‘retro’ can be used for, music, art, videogames, architecture, television, sometimes, it can also suggest an entire outlook on life. Up until the 1960s, interiors were decorated with antiques, during the 1960s in London shops started selling pieces of second hand furniture. These shops were different from the antique shops because they sold daily life objects from the recent past. These objects used to be seen as junk, Victorian enamel signs, stuffed bears, old furniture painted with union jacks, a new way of producing and consuming the past emerged and a broader range of objects from the recent past was used for new designs. Before the word came into use in the 1970s, the practise of adopting old styles for new designs was already common. Throughout the 19th and 20th centuries, designers borrowed from the past, the difference is that since the 1960s people started to refer to the recent past. In the 1980s, design history emerged as a discipline and several histories of design were published, the access to these overviews and the ability to experiment with computer design programs has caused an increase of retro designed objects in the last decades
28.
Wayback Machine
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The Internet Archive launched the Wayback Machine in October 2001. It was set up by Brewster Kahle and Bruce Gilliat, and is maintained with content from Alexa Internet, the service enables users to see archived versions of web pages across time, which the archive calls a three dimensional index. Since 1996, the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes and it revisits sites every few weeks or months and archives a new version. Sites can also be captured on the fly by visitors who enter the sites URL into a search box, the intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down. The overall vision of the machines creators is to archive the entire Internet, the name Wayback Machine was chosen as a reference to the WABAC machine, a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show, an animated cartoon. These crawlers also respect the robots exclusion standard for websites whose owners opt for them not to appear in search results or be cached, to overcome inconsistencies in partially cached websites, Archive-It. Information had been kept on digital tape for five years, with Kahle occasionally allowing researchers, when the archive reached its fifth anniversary, it was unveiled and opened to the public in a ceremony at the University of California, Berkeley. Snapshots usually become more than six months after they are archived or, in some cases, even later. The frequency of snapshots is variable, so not all tracked website updates are recorded, Sometimes there are intervals of several weeks or years between snapshots. After August 2008 sites had to be listed on the Open Directory in order to be included. As of 2009, the Wayback Machine contained approximately three petabytes of data and was growing at a rate of 100 terabytes each month, the growth rate reported in 2003 was 12 terabytes/month, the data is stored on PetaBox rack systems manufactured by Capricorn Technologies. In 2009, the Internet Archive migrated its customized storage architecture to Sun Open Storage, in 2011 a new, improved version of the Wayback Machine, with an updated interface and fresher index of archived content, was made available for public testing. The index driving the classic Wayback Machine only has a bit of material past 2008. In January 2013, the company announced a ground-breaking milestone of 240 billion URLs, in October 2013, the company announced the Save a Page feature which allows any Internet user to archive the contents of a URL. This became a threat of abuse by the service for hosting malicious binaries, as of December 2014, the Wayback Machine contained almost nine petabytes of data and was growing at a rate of about 20 terabytes each week. Between October 2013 and March 2015 the websites global Alexa rank changed from 162 to 208, in a 2009 case, Netbula, LLC v. Chordiant Software Inc. defendant Chordiant filed a motion to compel Netbula to disable the robots. Netbula objected to the motion on the ground that defendants were asking to alter Netbulas website, in an October 2004 case, Telewizja Polska USA, Inc. v. Echostar Satellite, No.02 C3293,65 Fed. 673, a litigant attempted to use the Wayback Machine archives as a source of admissible evidence, Telewizja Polska is the provider of TVP Polonia and EchoStar operates the Dish Network
29.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
30.
Metalworking
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Metalworking is the process of working with metals to create individual parts, assemblies, or large-scale structures. The term covers a range of work from large ships and bridges to precise engine parts. It therefore includes a wide range of skills, processes. Metalworking is a science, art, hobby, industry and trade and its historical roots span cultures, civilizations, and millennia. Metalworking has evolved from the discovery of smelting various ores, producing malleable and ductile metal useful for tools, modern metalworking processes, though diverse and specialized, can be categorized as forming, cutting, or joining processes. Todays machine shop includes a number of machine tools capable of creating a precise, the oldest archaeological evidence of copper mining and working was the discovery of a copper pendant in northern Iraq from 8,700 BCE. The earliest substantiated and dated evidence of metalworking in the Americas was the processing of copper in Wisconsin, Copper was hammered until brittle then heated so it could be worked some more. This technology is dated to about 4000-5000 BCE, the oldest gold artifacts in the world come from the Bulgarian Varna Necropolis and date from 4450 BCE. Not all metal required fire to obtain it or work it, isaac Asimov speculated that gold was the first metal. His reasoning is that by its chemistry it is found in nature as nuggets of pure gold, in other words, gold, as rare as it is, is sometimes found in nature as the metal that it is. There are a few metals that sometimes occur natively. Almost all other metals are found in ores, a mineral-bearing rock, another feature of gold is that it is workable as it is found, meaning that no technology beyond a stone hammer and anvil to work the metal is needed. This is a result of properties of malleability and ductility. The earliest tools were stone, bone, wood, and sinew, at some unknown point the connection between heat and the liberation of metals from rock became clear, rocks rich in copper, tin, and lead came into demand. These ores were mined wherever they were recognized, remnants of such ancient mines have been found all over Southwestern Asia. Metalworking was being carried out by the South Asian inhabitants of Mehrgarh between 7000–3300 BCE, the end of the beginning of metalworking occurs sometime around 6000 BCE when copper smelting became common in Southwestern Asia. Ancient civilisations knew of seven metals. Here they are arranged in order of their potential, Iron +0.44 V
31.
Computer-aided design
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Computer-aided design is the use of computer systems to aid in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, CAD output is often in the form of electronic files for print, machining, or other manufacturing operations. The term CADD is also used and its use in designing electronic systems is known as electronic design automation, or EDA. In mechanical design it is known as mechanical design automation or computer-aided drafting, however, it involves more than just shapes. CAD may be used to design curves and figures in space, or curves, surfaces. CAD is also used to produce computer animation for special effects in movies, advertising and technical manuals. The modern ubiquity and power of computers means that even perfume bottles, because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics, and discrete differential geometry. The design of models for object shapes, in particular, is occasionally called computer-aided geometric design. Eventually CAD provided the designer with the ability to perform engineering calculations, during this transition, calculations were still performed either by hand or by those individuals who could run computer programs. CAD was a change in the engineering industry, where draftsmen, designers. It did not eliminate departments, as much as it merged departments and empowered draftsman, CAD is just another example of the pervasive effect computers were beginning to have on industry. Current computer-aided design software packages range from 2D vector-based drafting systems to 3D solid, modern CAD packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle, even from the inside looking out. Some CAD software is capable of mathematical modeling, in which case it may be marketed as CAD. CAD technology is used in the design of tools and machinery and in the drafting and design of all types of buildings and it can also be used to design objects. Furthermore, many CAD applications now offer advanced rendering and animation capabilities so engineers can better visualize their product designs, 4D BIM is a type of virtual construction engineering simulation incorporating time or schedule related information for project management. CAD has become an important technology within the scope of computer-aided technologies, with benefits such as lower product development costs. CAD enables designers to layout and develop work on screen, print it out, computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question. Document management and revision control using Product Data Management, potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD
32.
Computer-aided manufacturing
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Computer-aided manufacturing is the use of software to control machine tools and related ones in the manufacturing of workpieces. CAM is now a used in schools and lower educational purposes. CAM is used in schools alongside computer-aided design to create objects. Historically, CAM software was seen to have shortcomings that necessitated an overly high level of involvement by skilled CNC machinists. Fallows created the first CAD software but this had severe shortcomings and was taken back into the developing stage. CAM software would output code for the least capable machine, as machine tool control added on to the standard G-code set for increased flexibility. In some cases, such as set up CAM software or specific tools. None of these issues were so insurmountable that an engineer or skilled machine operator could not overcome for prototyping or small production runs. In high production or high precision shops, a different set of problems were encountered where an experienced CNC machinist must both hand-code programs and run CAM software, integration of CAD with other components of CAD/CAM/CAE Product lifecycle management environment requires an effective CAD data exchange. CAM packages could not, and still cannot, reason as a machinist can and they could not optimize toolpaths to the extent required of mass production. Users would select the type of tool, machining process and paths to be used, while an engineer may have a working knowledge of G-code programming, small optimization and wear issues compound over time. Mass-produced items that require machining are often created through casting or some other non-machine method. This enables hand-written, short, and highly optimized G-code that could not be produced in a CAM package. At least in the United States, there is a shortage of young, skilled machinists entering the workforce able to perform at the extremes of manufacturing, high precision and mass production. User confidence is built on 3D visualization through a closer integration with the 3D CAD environment. Manufacturing complexity The manufacturing environment is increasingly complex, the need for CAM and PLM tools by buMs are NC programmer or machinist is similar to the need for computer assistance by the pilot of modern aircraft systems. The modern machinery cannot be used without this assistance. Todays CAM systems support the range of machine tools including, turning,5 axis machining
33.
Stewart platform
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Devices placed on the top plate can be moved in the six degrees of freedom in which it is possible for a freely-suspended body to move. These are the three linear movements x, y, z, and the three rotations pitch, roll, & yaw, the terms six-axis or 6-DoF platform are also used, also synergistic. Although the short title Stewart Platform is now used for this jack layout, to be more precise, the original Stewart platform had a slightly different design. See the more detailed references at the end of this article, because the device has six jacks, it is often also known as a hexapod. The trademarked name hexapod was originally for Stewart platforms used in machine tools, however, the term is now used for 6-jack platforms outside of the machine tool area, since it simply means six legs. The Stewart platform design is used in flight simulation, particularly in the so-called full flight simulator for which all 6 degrees of freedom are required. In this role, the payload is a replica cockpit and a display system, normally of several channels. Payload weights in the case of a flight simulator for a large transport aircraft can be up to about 15,000 kilogrammes. Similar platforms are used in driving simulators, typically mounted on large x-y tables to simulate short term acceleration, long term acceleration can be simulated by tilting the platform, and an active research area is how to mix the two. James S. Albus of the National Institute of Standards and Technology developed the RoboCrane, the Low impact docking system developed by NASA uses a Stewart platform to manipulate space vehicles during the docking process. The Computer Assisted Rehabilitation Environment developed by Motek Medical uses a Stewart platform coupled with virtual reality to do advanced biomechanical and clinical research, dr. J. Eric Gough was an automotive engineer and worked at Fort Dunlop, the Dunlop Tyres factory in Birmingham, England. He developed his Universal Tyre-Testing Machine in the 1950s and his platform was operational by 1954, the rig was able to mechanically test tyres under combined loads. Dr. Gough died in 1972 but his testing rig continued to be used up until the late 1980s when the factory was closed down and his rig was saved and transported to the Science Museum storage facility at Wroughton near Swindon. Parallel manipulator Robot kinematics Acceleration onset cueing Linear actuator Bonev, I. A, the True Origins of Parallel Robots, ParalleMIC online review Pictures of the NIST/Ingersoll prototype octahedral hexapod Hexapod Structures for Surgery Hexapod for Astronomy
34.
Die head
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A die head is a threading die that is used in the high volume production of threaded components. Die heads are used on lathes, turret lathes, screw machines. They may be used for cutting a thread or rolling a thread. They may also be used for internal or external thread cutting, in operation, there are usually four moveable chasers that cut the thread then back away from the work to permit rapid removal of the tool. The lower picture at the shows four sets of chasers. Each set of chasers is designed to cut a different thread, one set of chasers would be used at a time, each chaser is inserted into the die head and the die head is closed bringing the chasers down to their cutting position. When sufficient length of thread has been cut the die head will open allowing for rapid retraction of the head without interference with the newly formed thread, the die head shown cuts an outside thread. There are also collapsible die heads that are used to cut an internal thread, the bottom picture shows a Die Head used for Thread Rolling. A Rolled Thread may have greater strength than a cut thread, hartness Flat Turret Lathe Manual, A Hand Book for Operators. Springfield, Vermont and London, Jones & Lamson Machine Company
35.
Drill
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The attachment is gripped by a chuck at one end of the drill and rotated while pressed against the target material. The tip, and sometimes edges, of the tool does the work of cutting into the target material. This may be slicing off thin shavings, grinding off small particles, crushing and removing pieces of the workpiece, countersinking, counterboring, drills are commonly used in woodworking, metalworking, construction and do-it-yourself projects. Specially designed drills are used in medicine, space missions. Drills are available with a variety of performance characteristics, such as power. Around 35,000 BC, Homo sapiens discovered the benefits of the application of rotary tools and this would have rudimentarily consisted of a pointed rock being spun between the hands to bore a hole through another material. This led to the drill, a smooth stick, that was sometimes attached to flint point. This was used by ancient civilizations around the world including the Mayans. The earliest perforated artifacts, such as bone, ivory, shells, bow drill are the first machine drills, as they convert a back-and forth motion to a rotary motion, and they can be traced back to around 10,000 years ago. It was discovered that tying a cord around a stick, and then attaching the ends of the string to the ends of a stick, allowed a user to drill quicker, mainly used to create fire, bow-drills were also used in ancient woodwork, stonework and dentistry. There are hieroglyphs depicting Egyptian carpenters and bead makers in a tomb at Thebes using bow-drills, the earliest evidence of these tools being used in Egypt dates back to around 2500 BCE. The usage of bow-drills was widely spread through Europe, Africa, Asia and North America, over the years many slight variations of bow and strap drills have developed for the various uses of either boring through materials or lighting fires. The core drill was developed in ancient Egypt by 3000 BC, the pump drill was invented during Roman times. It consists of a vertical spindle aligned by a piece of horizontal wood, the hollow-borer tip, first used around the 13th century, consisted of a stick with a tubular shaped piece of metal on the end, such as copper. This allowed a hole to be drilled while only actually grinding the outer section of it and this completely separates the inner stone or wood from the rest, allowing the drill to pulverize less material to create a similarly sized hole. The auger allowed for more torque for larger holes and it is uncertain when the Brace and Bit was invented, however, the earliest picture found so far dates from the 15th century. It is a type of hand crank drill that consists of two parts as seen in the picture, the brace, on the upper half, is where the user holds and turns it and on the lower part is the bit. The bit is interchangeable as bits wear down, the auger uses a rotating helical screw similar to the Archimedean screw-shaped bit that is common today
36.
Drill bit
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Drill bits are cutting tools used to remove material to create holes, almost always of circular cross-section. Drill bits come in sizes and shape and can create different kinds of holes in many different materials. In order to create holes drill bits are attached to a drill, the drill will grasp the upper end of a bit called the shank in the chuck. Drill bits come in sizes, described in the drill bit sizes article. A comprehensive drill bit and tap size chart lists metric and imperial sized drill bits alongside the required screw tap sizes, there are also certain specialized drill bits that can create holes with a non-circular cross-section. While the term drill may refer to either a machine or a drill bit for use in a drilling machine. In this article, for clarity, drill bit or bit is used throughout to refer to a bit for use in a drilling machine, Drill bit geometry has several characteristics, The spiral in the drill bit controls the rate of chip removal. A fast spiral drill bit is used in high feed rate applications under low spindle speeds, the point angle, or the angle formed at the tip of the bit, is determined by the material the bit will be operating in. Harder materials require a larger point angle, and softer materials require a sharper angle, the correct point angle for the hardness of the material influences wandering, chatter, hole shape, and wear rate. The lip angle determines the amount of support provided to the cutting edge, a greater lip angle will cause the bit to cut more aggressively under the same amount of point pressure as a bit with a smaller lip angle. Both conditions can cause binding, wear, and eventual failure of the tool. The proper amount of lip clearance is determined by the point angle, the length of a bit determines how deep a hole can be drilled, and also determines the stiffness of the bit and accuracy of the resultant hole. While longer bits can drill deeper holes, they are flexible meaning that the holes they drill may have an inaccurate location or wander from the intended axis. Twist drill bits are available in lengths, referred to as Stub-length or Screw-Machine-length, the extremely common Jobber-length. Most drill bits for use have straight shanks. For heavy duty drilling in industry, bits with tapered shanks are sometimes used, other types shanks used include hex-shaped, and various proprietary quick release systems. The diameter-to-length ratio of the bit is usually between 1,1 and 1,10. Much higher ratios are possible, but the higher the ratio, the best geometry to use depends upon the properties of the material being drilled
37.
Drill bit shank
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The shank is the end of a drill bit grasped by the chuck of a drill. The cutting edges of the drill bit contact the workpiece, and are connected via the shaft with the shank, in many cases a general-purpose arrangement is used, such as a bit with cylindrical shaft and shank in a three-jaw chuck which grips a cylindrical shank tightly. Different shank and chuck combination can deliver improved performance, such as allowing higher torque, greater centering accuracy, or moving the bit and this shank was common before 1850, and is still in production. At first, the shank was just rammed into a square hole in the end of the drill. Over time, various designs have been invented, and modern chucks can grasp. It has been difficult to find a reference to the angle of the taper, but 7 different bits were measured. The whole of the bit, shaft and shank, is usually of the same diameter. It is held usually in a 3-jaw drill chuck, bits of diameter too small to grip firmly can have straight shanks of larger diameter than the drill, which can be held firmly in a standard size collet or chuck. Large drill bits can have straight shanks narrower than the drill diameter so that they can be fitted in chucks not able to chuck the full diameter, such a drill bit is called a reduced-shank or blacksmiths drill. For example, this allows a 1/2 bit to be used in a pistol-grip drills 3/8 chuck, one particular type of reduced-shank drill bits are Silver & Deming bits, whose sets run from 9/16 to 1-1/2 drill body diameter with a standard 1/2 reduced shank for all. This allows drill presses with 1/2 chucks to run the larger drills, s&D bits are 6 long with a 3 flute length. A hex shank can be grasped by a 3-jaw drill chuck or held in a specifically for hex shanks. Quarter-inch hex shanks are common for machine screwdriver bits and have spread from that application to be used for drill bits that are compatible with screwdriver machinery. The SDS shank has the advantage of fitting into a simple spring-loaded chuck and this shank and chucks made for it are especially suited to hammer drilling with masonry drills in stone and concrete. The drill bit is not held solidly in the chuck, but can slide back and forth like a piston, it not slip during rotation due to the non-circular shank cross-section. Rotational drive uses the sliding keyways that open to the end of the shank, the smaller indentations that do not open to the end are grasped by the chuck to prevent the drill bit falling out. The hammer of the hits the flat end of the shank. The shank must be lubricated with grease to allow it to slide in the chuck, there are three standard sizes of SDS, SDS-plus, SDS-Top and SDS-max
38.
Drill bit sizes
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Drill bits are the cutting tools of drilling machines. They can be made in any size to order, but standards organizations have defined sets of sizes that are produced routinely by drill bit manufacturers, in the U. S. fractional inch and gauge drill bit sizes are in common use. In nearly all countries, metric drill bit sizes are most common. The British Standards on replacing gauge size drill bits with metric sizes in the UK was first published in 1959, a comprehensive table for metric, fractional wire and tapping sizes can be found at the drill and tap size chart. Metric drill bit sizes define the diameter of the bit in terms of standard metric lengths, Standards organizations define sets of sizes that are conventionally manufactured and stocked. For example, British Standard BS328 defines sizes from 0.2 mm to 25.0 mm. This reflects both the smaller drilled hole diameter tolerance possible on smaller holes and the wishes of designers to have drill bit sizes available within at most 10% of an arbitrary hole size, the price and availability of particular size bits does not change uniformly across the size range. Bits at size increments of 1 mm are most commonly available, sets of bits in 1 mm increments might be found on a market stall. In 0.5 mm increments, any hardware store, in 0.1 mm increments, any engineers store. Sets are not commonly available in smaller size increments, except for drill bits below 1 mm diameter, drill bits of the less routinely used sizes, such as 2.55 mm, would have to be ordered from a specialist drill bit supplier. This subsetting of standard sizes is in contrast to practice with number gauge drill bits. Metric dimensioning is routinely used for drill bits of all types, for example, a set of Forstner bits may contain 10,15,20,25 and 30 mm diameter cutters. ANSI B94. 11M-1979 sets size standards for jobber-length straight-shank twist drill bits from 1/64 inch through 1 inch in 1/64 inch increments, drill bit sizes are written down on paper and etched onto bits as irreducible fractions. So, instead of 78/64 inch, or 1 14/64 inch, below is a chart providing the decimal-fraction equivalents that are most relevant to fractional-inch drill bit sizes. Fractional inch drill bit sizes are still in use in the US. In the past, they were elsewhere, but they have now been largely discarded in favour of metric sizes. Number drill bit gauge sizes range from size 80 to size 1 followed by letter gauge size A to size Z. Although the ASME B94. 11M twist drill standard, for example, lists sizes as small as size 97, sizes smaller than 80 are rarely encountered in practice
39.
Drilling
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Drilling is a cutting process that uses a drill bit to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multipoint, the bit is pressed against the workpiece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the workpiece, cutting off chips from the hole as it is drilled, in rock drilling, the hole is usually not made through a circular cutting motion, though the bit is usually rotated. Instead, the hole is made by hammering a drill bit into the hole with quickly repeated short movements. The hammering action can be performed from outside of the hole or within the hole, drills used for horizontal drilling are called drifter drills. In rare cases, specially-shaped bits are used to cut holes of non-circular cross-section, drilled holes are characterized by their sharp edge on the entrance side and the presence of burrs on the exit side. Also, the inside of the hole usually has helical feed marks and this causes the workpiece to become more susceptible to corrosion and crack propagation at the stressed surface. A finish operation may be done to avoid these detrimental conditions, for fluted drill bits, any chips are removed via the flutes. Chips may form long spirals or small flakes, depending on the material, the type of chips formed can be an indicator of the machinability of the material, with long chips suggesting poor material machinability. When possible drilled holes should be located perpendicular to the workpiece surface and this minimizes the drill bits tendency to walk, that is, to be deflected from the intended center-line of the bore, causing the hole to be misplaced. The higher the ratio of the drill bit, the greater the tendency to walk. Constraining the position of the drill bit using a jig with drill bushings Surface finish produced by drilling may range from 32 to 500 microinches. Finish cuts will generate surfaces near 32 microinches, and roughing will be near 500 microinches, cutting fluid is commonly used to cool the drill bit, increase tool life, increase speeds and feeds, increase the surface finish, and aid in ejecting chips. Application of these fluids is usually done by flooding the workpiece with coolant and lubricant or by applying a spray mist, in deciding which drill to use it is important to consider the task at hand and evaluate which drill would best accomplish the task. There are a variety of styles that each serve a different purpose. The subland drill is capable of drilling more than one diameter, the spade drill is used to drill larger hole sizes. The indexable drill is useful in managing chips, the purpose of spot drilling is to drill a hole that will act as a guide for drilling the final hole. The hole is only drilled part way into the workpiece because it is used to guide the beginning of the next drilling process
40.
Tap and die
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Taps and dies are tools used to create screw threads, which is called threading. Many are cutting tools, others are forming tools, a tap is used to cut or form the female portion of the mating pair. A die is used to cut or form the male portion of the mating pair, the process of cutting or forming threads using a tap is called tapping, whereas the process using a die is called threading. Both tools can be used to clean up a thread, which is called chasing, however, using an ordinary tap or die to clean threads will generally result in the removal of some material, which will result in looser and weaker threads. Because of this, threads are typically cleaned using special taps and dies made for this purpose, chasers are made of softer materials and are not capable of cutting new threads, however they are still tighter fitting than actual fasteners and are fluted like regular taps and dies. One particularly common use is for automotive spark plug threads, which suffer from corrosion. As the loads grew ever heavier, bigger and stronger bolts were needed to resist breakage, some nuts and bolts were measured by the foot or yard. This development eventually led to a replacement of wood parts with metal parts of an identical measure. When a wooden part broke, it snapped, ripped. Metalworking taps and dies were made by their users during the 18th and 19th centuries, using such tools as lathes and files for the shaping. Thus builders of, for example, locomotives, firearms, or textile machinery were likely to make their own taps, during the 19th century the machining industries evolved greatly, and the practice of buying taps and dies from suppliers specializing in them gradually supplanted most such in-house work. Joseph Clement was one such early vendor of taps and dies, with the introduction of more advanced milling practice in the 1860s and 1870s, tasks such as cutting a taps flutes with a hand file became a thing of the past. In the early 20th century, thread-grinding practice went through significant evolution, further advancing the state of the art of cutting screw threads, including those of taps and dies. During the 19th and 20th centuries, thread standardization was evolving simultaneously with the techniques of thread generation, including taps, the largest tap and die company to exist in the United States was Greenfield Tap & Die of Greenfield, Massachusetts. GTD was so vital to the Allied war effort from 1940–1945 that anti-aircraft guns were placed around its campus in anticipation of possible Axis air attack. The GTD brand is now a part of Widia Products Group, a tap cuts a thread on the inside surface of a hole, creating a female surface which functions like a nut.5 threads of taper is typical. This feature enables a bottoming tap to cut threads to the bottom of a blind hole, in the US, they are commonly known as bottoming taps, but in Australia and Britain they are also known as plug taps. Intermediate tap, second tap, or plug tap The tap illustrated in the middle of the image has tapered cutting edges, the number of tapered threads typically ranges from 3 to 5
41.
Tap wrench
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A tap wrench is a hand tool used to turn taps or other small tools, such as hand reamers and screw extractors. There are two types of tap wrenches, double-end adjustable wrenches and T-handle wrenches. Double-end adjustable wrenches, also known as bar wrenches, have one threaded handle which is attached to one of the clamps, the clamp is opened to insert the tool and then tightened down against the tool to secure it. This type of tap wrench is used with larger taps and where there is room to turn a larger wrench and this type of wrench uses a collet to secure the tool. The collet design has two pieces, a threaded nosecap and four fingers, the collet fingers thread on the outside. The nosecap is tapered, which causes the fingers to clamp onto the tool and this style tap wrench is useful in confined spaces or where extra reach is required. The hole which forms the collet fingers may be sloped or may be stepped. Numerous sizes of tap wrenches are required to cover the size range of tool heads. Generally speaking, the smallest size which accommodates the tool head is recommended because it reduces the risk of breakage from excessive force
42.
Threading (manufacturing)
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Threading is the process of creating a screw thread. More screw threads are produced each year than any other machine element, there are many methods of generating threads, including subtractive methods, deformative or transformative methods, additive methods, or combinations thereof. There are various methods for generating screw threads, in general, certain thread-generating processes tend to fall along certain portions of the spectrum from toolroom-made parts to mass-produced parts, although there can be considerable overlap. Threads of metal fasteners are usually created on a rolling machine. They may also be cut with a lathe, tap or die, rolled threads are stronger than cut threads, with increases of 10% to 20% in tensile strength and possibly more in fatigue resistance and wear resistance. A common method of threading is cutting with taps and dies, unlike drill bits, hand taps do not automatically remove the chips they create. A hand tap cannot cut its threads in a single rotation because it creates long chips which quickly jam the tap and it may be necessary to periodically remove the tap from the hole to clear the chips, especially when a blind hole is threaded. For continuous tapping operations specialized spiral point or gun taps are used to eject the chips, single-point threading, also colloquially called single-pointing, is an operation that uses a single-point tool to produce a thread form on a cylinder or cone. The tool moves linearly while the rotation of the workpiece determines the lead of the thread. The process can be done to create external or internal threads, in external thread cutting, the piece can either be held in a chuck or mounted between two centers. With internal thread cutting, the piece is held in a chuck, the tool moves across the piece linearly, taking chips off the workpiece with each pass. Usually 5 to 7 light cuts create the depth of the thread. Today engine lathes and CNC lathes are the used machines for single-point threading. On CNC machines, the process is quick and easy due to the ability to constantly track the relationship of the tool position. CNC software includes canned cycles, that is, preprogrammed subroutines, parameters are entered, and the machine does the rest. Threads may be milled with a milling cutter if the correct helical toolpath can be arranged. This was formerly arranged mechanically, and it was suitable for mass-production work although uncommon in job-shop work, there are various types of thread milling, including several variants of form-milling and a combination of drilling and threading with one cutter, called thrilling. Form-milling uses either a single- or multiple-form cutter, in one variant of form-milling, the single-form cutter is tilted to the helix angle of the thread and then fed radially into the blank
43.
Abrasive
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An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, in short, the Ceramics which are used to cut, grind and polish other softer materials are known as Abrasives. Abrasives are extremely commonplace and are used extensively in a wide variety of industrial, domestic. This gives rise to a variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding. Files are not abrasives, they remove material not by scratching or rubbing, however, diamond files are a form of coated abrasive. Abrasives generally rely upon a difference in hardness between the abrasive and the material being worked upon, the abrasive being the harder of the two substances. Diamond, an abrasive, for instance occurs both naturally and is industrially produced, as is corundum which occurs naturally but which is nowadays more commonly manufactured from bauxite. However, even softer minerals like calcium carbonate are used as abrasives and these minerals are either crushed or are already of a sufficiently small size to permit their use as an abrasive. These grains, commonly called grit, have rough edges, often terminating in points which will decrease the area in contact. The abrasive and the material to be worked are brought into contact while in motion to each other. Abrasives may be classified as natural or synthetic. When discussing sharpening stones, natural stones have long been considered superior, many synthetic abrasives are effectively identical to a natural mineral, differing only in that the synthetic mineral has been manufactured rather than been mined. Impurities in the mineral may make it less effective. Natural abrasives are often sold as dressed stones, usually in the form of a rectangular block, a bonded abrasive is composed of an abrasive material contained within a matrix, although very fine aluminium oxide abrasive may comprise sintered material. This matrix is called a binder and is often a clay, a resin and this mixture of binder and abrasive is typically shaped into blocks, sticks, or wheels. The most usual abrasive used is aluminium oxide, also common are silicon carbide, tungsten carbide and garnet. Artificial sharpening stones are often a bonded abrasive and are available as a two sided block, each side being a different grade of grit
44.
Angle grinder
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An angle grinder, also known as a side grinder or disc grinder, is a handheld power tool used for grinding and polishing. Angle grinders can be powered by a motor, petrol engine or compressed air. The motor drives a geared head at a right-angle on which is mounted an abrasive disc or a thinner cut-off disc, angle grinders typically have an adjustable guard and a side-handle for two-handed operation. Certain angle grinders, depending on their range, can be used as sanders. The backing system is made of hard plastic, phenolic resin. Angle grinders are standard equipment in metal fabrication shops and on construction sites and they are also common in machine shops, along with die grinders and bench grinders. Angle grinders may be used for removing material from a piece. The angle grinder has large bearings to counter side forces generated during cutting, unlike a power drill, angle grinders are widely used in metalworking and construction, as well as in emergency rescues. They are commonly found in workshops, service garages and auto repair shops. There is a variety of angle grinders to choose from when trying to find the right one for the job. The most important factors in choosing the right grinder are the disc size, other factors include power source, rpm, and arbor size. Generally disc size and power increase together, disc size is usually measured in inches or millimetres. Common disc sizes for angle grinders in the U. S. A. include 4,4.5,5,6,7,9 and 12 inches, discs for pneumatic grinders also come much smaller. Pneumatic grinders are used for lighter duty jobs where more precision is required. Electric grinders are commonly used for larger, heavy duty jobs. However, there are small electric grinders and large pneumatic grinders. Through a sound level and vibrations study conducted by the National Institute for Occupational Safety and Health. In addition, angle grinders produce sparks when cutting ferrous metals and they also produce shards cutting other materials
