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. The processes that have this common theme, controlled material removal, are today collectively known as subtractive manufacturing, in distinction from processes of controlled material addition, which are known as additive manufacturing. What the "controlled" part of the definition implies can vary, but it always implies the use of machine tools. Machining is a part of the manufacture of many metal products, but it can be used on materials such as wood, plastic and composites. A person who specializes in machining is called a machinist. A room, building, or company where machining is done is called a machine shop. 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 and other cutting machines; the precise meaning of the term machining has evolved over the past one and a half centuries as technology has advanced.
In the 18th century, the word machinist meant a person who built or repaired machines. This person's work was done by hand, using processes such as the carving of wood and the hand-forging and hand-filing of metal. At the time and builders of new kinds of engines, such as James Watt or John Wilkinson, would fit the definition; the noun machine tool and the verb to machine did not yet exist. Around the middle of the 19th century, the latter words were coined as the concepts that they described evolved into widespread existence. Therefore, during the Machine Age, machining referred to the "traditional" machining processes, such as turning, drilling, broaching, shaping, planing and tapping. In these "traditional" or "conventional" machining processes, machine tools, such as lathes, milling machines, drill presses, or others, are used with a sharp cutting tool to remove material to achieve a desired geometry. Since the advent of new technologies in the post–World War II era, such as electrical discharge machining, electrochemical machining, electron beam machining, photochemical machining, ultrasonic machining, the retronym "conventional machining" can be used to differentiate those classic technologies from the newer ones.
In current usage, the term "machining" without qualification implies the traditional machining processes. In the decades of the 2000s and 2010s, as additive manufacturing evolved beyond its earlier laboratory and rapid prototyping contexts and began to become common throughout all phases of manufacturing, the term subtractive manufacturing became common retronymously in logical contrast with AM, covering any removal processes previously covered by the term machining; the two terms are synonymous, although the long-established usage of the term machining continues. This is comparable to the idea that the verb sense of contact evolved because of the proliferation of ways to contact someone but did not replace the earlier terms such as call, talk to, or write to; the three principal machining processes are classified as turning and milling. Other operations falling into miscellaneous categories include shaping, boring and sawing. Turning operations are operations that rotate the workpiece as the primary method of moving metal against the cutting tool.
Lathes are the principal machine tool used in turning. Milling operations are operations in which the cutting tool rotates to bring cutting edges to bear against the workpiece. Milling machines are the principal 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 in drill presses but sometimes on lathes or mills. Miscellaneous operations are operations that speaking may not be machining operations in that they may not be swarf producing operations but these operations are performed at a typical machine tool. Burnishing is an example of a miscellaneous operation. Burnishing 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.
For example, a workpiece may be required to have a specific outside diameter. A lathe is a machine tool that can be used to create that diameter by rotating a metal workpiece, so that a cutting tool can cut metal away, creating a smooth, round surface matching the required diameter and surface finish. A drill can be used to remove metal in the shape of a cylindrical hole. Other tools that may be used for various types of metal removal are milling machines and grinding machines. Many of these same techniques are used in woodworking. More recent, advanced machining techniques include precision CNC machining, electrical discharge machining, electro-chemical erosion, laser cutting, or water jet cutting to shape metal workpieces; as a commercial venture, machining is performed in a machine shop, which consists of one or more workrooms containing major machine tools. Although a machine shop can be a stand-alone operation, many businesses maintain internal machine shops which support specialized needs of the business.
Machining requires attention to many details for a workpiece to meet the specificati
James Parker was a major general in the United States Army and a Medal of Honor recipient for his role in the Philippine–American War during 1899. His son, Cortlandt Parker became a major general in the United States Army. Parker was born in Newark, New Jersey on February 20, 1854, a son of Cortlandt Parker and Elizabeth Parker, he was a member of a family long active in New Jersey government and politics. His father was a prominent attorney, his grandfather, James Parker was a member of Congress. His brother, Richard W. Parker served in the United States House of Representatives. Parker's nephew Henry Parkman Jr. was the son of Parker's sister Mary. James Parker was educated at Newark Academy, Phillips Academy and Rutgers College, where he was admitted to the Zeta Psi fraternity, he graduated from the United States Military Academy at West Point, New York in 1876, 31st in a class of 50 cadets, was appointed second lieutenant. He spent his early years serving in the Fourth United States Cavalry participating in the Indian Wars of the Southwest.
His military career was influenced by the magnetic personality of the commander of the Fourth Cavalry, General Ranald S. Mackenzie, a legend for his success as a cavalry commander in the American Civil War. In May 1886, First Lieutenant Parker commanded one column of troops sent into Mexico to track down the famous Apache leader Geronimo and his band, cooperated with Captain Henry W. Lawton and First Lieutenant Charles B. Gatewood when Geronimo was captured, he served as second in command of the 12th New York Infantry in Cuba during the Spanish–American War and saw significant combat while commanding the 45th Volunteer Infantry in the Philippine–American War during 1899 where he earned the Medal of Honor. From 1903 to 1904, he served as Head of Militia Affairs in the Adjutant General's office. During the First World War, General Parker served as Commander of the Southern Department, Fort Sam Houston, Texas from 31 March 1917 to 25 August 1917. Citation: While in command of a small garrison repulsed a savage night attack by overwhelming numbers of the enemy, fighting at close quarters in the dark for several hours.
In addition to the Medal of Honor, Major General Parker was awarded the Distinguished Service Medal and three Silver Stars for his service and battlefield exploits. Full list of decorations and medals: Medal of Honor Distinguished Service Medal Silver Star with two oak leaf clusters Indian Campaign Medal Spanish War Service Medal Philippine Campaign Medal World War I Victory Medal He retired on February 20, 1934 and moved to Newport, Rhode Island. Parker, James; the Mounted Rifleman. S. Army. Menasha, Wis: George Banta Pub. Co, 1916. OCLC 5508503 Parker, James; the Old Army. Philadelphia: Dorrance & Co, 1929. OCLC 518366 Parker died on June 2, 1934, he is buried in Saint Mary's Episcopal Churchyard, Rhode Island. His papers are held by the United States Military Academy. List of Medal of Honor recipients "James Parker". Claim to Fame: Medal of Honor recipients. Find a Grave. Retrieved 2007-11-24. "James Parker, Medal of Honor recipient". Philippine Insurrection. United States Army Center of Military History.
Retrieved 2007-11-24. Harrower, Gordon. "Submarine Skipper: Commander James Parker, Jr. USN". Military Images. Retrieved 2007-05-12
Devegeçidi Bridge known as Kara Köprü and Sultan Murad IV Köprüsü is a disused stone bridge of seven arches across the Devegeçidi stream 20 km north of Diyarbakır, in southeast Turkey, on the road to Ergani. There is a separate bridge across the same stream, also called the Devegeçidi Bridge 13.5 km to the east, near the stream's confluence with the Tigris river. There are three inscriptions on the southern portion of the bridge, one of which indicates that it was built in 1218 by the Artuqid ruler Melik Salih Nâsıreddin Mahmud; the bridge is made of basalt blocks, some finely dressed others less so and has seven pointed arches, of which the southern two are the broadest. Deve Geçidi Bridge was last repaired in 1972