Numerical control or numerically controlled (NC) machine tools are machines that are automatically operated by commands that are received by their processing units. NC machines were first developed soon after World War II and made it possible for large quantities of the desired components to be very precisely and efficiently produced (machined) in a reliable repetitive manner. These early machines were often fed instructions which were punched onto paper tape or punch cards. In the 1960s, NC machines largely gave way to CNC, or computer numerical control, machines. A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by the selective removal of metal. ... Combatants Allied Powers Axis Powers Commanders {{{commander1}}} {{{commander2}}} Strength {{{strength1}}} {{{strength2}}} Casualties 17 million military deaths 7 million military deaths World War II, also known as the Second World War (sometimes WW2 or WWII), was a mid-20th century conflict that engulfed much of the globe and is accepted as... A lathe is a common tool used in machining. ... A roll of punched tape Punched tape is an old-fashioned form of data storage, consisting of a long strip of paper in which holes are punched to store data. ... The punch card (or Hollerith card) is a recording medium for holding information for use by automated data processing machines. ... The 1960s decade refers to the years from 1960 to 1969, inclusive. ... A CNC Turning Center The abbreviation CNC stands for Computer(ized) Numerical(ly) Control(led), and refers specifically to the computer control of machine tools for the purpose of (repeatedly) manufacturing complex parts in metal as well as other materials, using a program written in a notation conforming to the... A computer is a machine capable of undergoing complex calculations. ...

Numerical Control (NC) was the precursor of today's Computer Numerical Control (CNC), which controls the automation of machine tools and the inherent tool processes for which they are designed. The CNC machine tool is the servo actuator of the CAD/CAM (Computer Assisted Design/Computer Assisted Manufacturing) technology both literally and figuratively. CNC inherits from NC the essential character of by-the-numbers interpolation of transition points in the work envelope of a mult-axis motion platform, based on the separation of programming from operations. The set of instructions, or "program" (usually an ASCII text file in which, in its simplest form, a line of text specifies the axial coordinates of a point in the work envelope) is prepared from a blueprint or CAD file and transferred to the memory of the CNC via floppy drive, serial data interface or a network connection. Once stored in the CNC memory and selected, the program is executed by pressing the appropriate key on the machine operator panel. The term servo can refer to: Servomechanism - usually just shortened to servo, is a device used to effect mechanical motion for a specified distance. ... An actuator is the mechanism by which an agent acts upon an environment. ... ...

Historical notes

The need of the U.S. Air Force for templates more precise than could be obtained by state-of-the-art methods of the late 1940s inspired John Parsons^[1], President of the Parsons Works of Traverse City, Michigan, to propose that a by-the-numbers technique (commonly used by machinists of that era) be placed under servo control with positional data generated by a computer, thereby providing much more data than would be practical by means of hand calculations. His concept was to machine to setpoints as guides for subsequent manual finishing, that is, to speed up a manual process so more points could be included. John T. Parsons (Detroit, October 13 1913–) pioneered numerical control for machine tools in the 1940s. ... A machinist is a tradesperson who specializes in making things out of metal or other solid material. ...

Mr. Parsons' project was enjoined by the Servo Mechanisms Laboratory of the Massachusetts Institute of Technology and redefined as interpolative positional control that caused the cutting tool to traverse a series of straight lines between defined points at a prescribed rate of travel. Thus, the cutting tool would be almost constantly on the programmed contour and would spend very little of its time making non-cutting moves.

In the M.I.T. scheme, a contour of constantly changing curvature was represented as a poly-line with the intersections between line segments being points on the curve, and the axial coordinates of these points were listed for execution in sequential order in the part program (much like the figure which results from connecting-the-dots in an activity book). The shorter the line segments the more accurately the poly-line would approximate the actual curve. Thus, M.I.T. retained separation of programming from operations while redefining the servo control as interpolative, rather than discretionary, positioning. M.I.T. demonstrated the first ever NC machine tool to a select group from the military, the aerospace industry, the machine tool industry and the technical media in September, 1952.

At the time when M.I.T. was developing numerical control, engineers at General Motors were putting position transducers on the lead screws of a conventional engine lathe and recording the motion of the axes as the machinist put the machine through its paces to make a workpiece. The machine was also fitted with a servo system that took data from the recording to reproduce the same sequence of motion to produce a second, third and more parts. This technique is called record/playback and it is reminiscent of a musician playing on a piano that has been modified to record the keystrokes on a paper chart which can be read by a player piano to reproduce the music. The popular novel Player Piano was inspired by this machine. The author, Kurt Vonnegut, was exposed to the machine when he worked as a publicist for General Electric. Conventional metalworking lathe See also: Lathe (tool) A metal lathe is a rigid machine tool designed to remove material from a workpiece, through the action of a cutting tool. ... The player piano is a type of piano that plays music without the need for a human pianist to depress the normal keys or pedals. ... Kurt Vonnegut Kurt Vonnegut Jr. ...

Record/playback is different than numerical control in that the program is produced by the machinist in the process of making the first part. The Air Force wanted numerical control and not record/playback because 1) the latter put the machinists who were union members in charge of program production, thus union strikes could result in unacceptable delays in military production, and 2) numerical control demonstrated the capability of producing complex parts that were not possible by the conventional manual methods used in the record/playback technique. The Air Force used its deep pockets to get its way and while American manufacturing may have been better served by the simpler Parsons concept or by record/playback, today this is a moot issue.

The electronic files used to control NC and CNC machines are often in a format called G-code, after Gerber Scientific Instruments^[2], a manufacturer of photoplotters and developer of the file format. The X-Y two-dimensional motion of photoplotters was extended to include the third Z axis, and along with special codes, allows milling machines to be steered in more than three axes. Many of the lines of text in the control files start with the ASCII letter G, thus the name; however, there are other commands that start with the letter D and M, as well as X and Y for coordinates. The file format became so widely used that it has been embodied in an EIA standard. G Code is a scheme to assist in the recording of television programs on video recorders. ... There are 95 printable ASCII characters, numbered 32 to 126. ... EIA may refer to the following: Electronic Industries Alliance Energy Information Administration Environmental Impact Assessment Enzyme-Linked Immunosorbent Assay Equity Indexed Annuity Exercise-induced anaphylaxis This is a disambiguation page, a list of pages that otherwise might share the same title. ...

Today

An entire manufacturing technology known as CAD/CAM has developed around the NC concept and, in addition, CNC with its powerful microprocessors and other enabling technologies proffered from the personal computing phenomenon has enabled the NC concept to branch into many variants, even a variant that is essentially record/playback. In the industry, these machines are called teach lathes.

In addition, powerful and well-crafted human/machine interfaces allow the machine operator to prepare programs by means of interactive displays which request only the definition of the machining operation and its required parameters (such as a "pocket" and its dimensions) and not the actual tool paths with all the calculations that are there required. Anyone who knows machining concepts and blueprint interpretation can produce programs at the machine without the need for CAD/CAM. Nonetheless, the vast majority of programs are now produced with the aid of CAD/CAM and, for most users, CNC today (for all its gigahertz microprocessors and megabytes of real time kernel software) is conceptually little different than the first NC demonstrated by the M.I.T. in 1952.

If there is a notable difference in concept, it is that CNC is no longer just for the spindle/cutting tool process of stock removal. It is for any processes that can be carried on machine tool motion platforms and that benefit from the separation of programming from operations, that is, from the CAD/CAM technology. These include lasing, welding, friction stir welding, ultrasonic welding, flame cutting, bending, spinning, pinning, gluing, fabric cutting, sewing, tape and fiber placement, routing, sawing and, undoubtedly, the industrial processes of tomorrow.

WikiProject Metalworking:
CNC, CAD, and CAM: Image File history File links Blacksmith-hammer-anvil-50x50. ... Turned chess pieces Metalworking is the craft and practice of working with metals to create parts or structures. ...	2.5D | CAD | CAE | CAM | CNC | G-code | Numerical control | Stewart platform 2. ... Computer-aided design (CAD) is the use of a wide range of computer-based tools that assist engineers, architects and other design professionals in their design activities. ... Computer-aided Engineering (often referred to as CAE) is a broad term describing the use of computer technology to aid in the design, manufacture, handling, or transport of goods. ... Integrating computer-aided manufacturing (CAM) with computer-aided design systems produces quicker and more efficient manufacturing processes. ... A CNC Turning Center The abbreviation CNC stands for Computer(ized) Numerical(ly) Control(led), and refers specifically to the computer control of machine tools for the purpose of (repeatedly) manufacturing complex parts in metal as well as other materials, using a program written in a notation conforming to the... G Code is a scheme to assist in the recording of television programs on video recorders. ... A Stewart platform is a kind of manipulator using an octahedral assembly of struts. ...
Metalworking topics:   Casting | CNC | Cutting machines | Cutting tools | Drilling and threading | Fabrication | Finishing | Grinding | Jewellery | lathe (tool) | Machining | Machine tooling | Measuring | Metalworking | Hand tools | Metallurgy | Milling | Occupations | Press tools | Smithing | Terminology | Welding One half of a bronze mold for casting a socketed spear head dated to the period 1400-1000 BC. This article is about the manufacturing process. ... A CNC Turning Center The abbreviation CNC stands for Computer(ized) Numerical(ly) Control(led), and refers specifically to the computer control of machine tools for the purpose of (repeatedly) manufacturing complex parts in metal as well as other materials, using a program written in a notation conforming to the... Turned chess pieces Metalworking is the craft and practice of working with metals to create parts or structures. ... Drilling is the process of using a drill bit in a drill to produce holes. ... A typical steel fabrication shop Fabrication is an industrial term generally applied to the building of metal machines and structures. ... Rotating abrasive wheel on a bench grinder. ... Jewellery (Jewelry in American spelling); comprises ornamental objects worn by persons, typically made with gems and precious metals. ... Conventional metalworking lathe In woodturning, metalworking, metal spinning, and glassworking, a lathe is a machine tool which spins a block of material so that when abrasive, cutting, or deformation tools are applied to the block, it can be shaped to produce an object which has rotational symmetry about an axis... A lathe is a common tool used in machining. ... A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by the selective removal of metal. ... Turned chess pieces Metalworking is the craft and practice of working with metals to create parts or structures. ... Metalworking hand tools are hand tools that are used in the metalworking field. ... Metallurgy is a domain of materials science and of materials engineering that studies the physical and chemical behavior of metallic elements and their mixtures, which are called alloys. ... Cutters for a milling machine. ... It has been suggested that this article or section be merged with Smith (metalwork). ... Power press with a fixed barrier guard A press, or a machine press is a tool used to work metal (typically steel) by changing its shape and internal structure. ... A smith or metalsmith is a person involved in the shaping of metal objects. ... This article needs to be wikified. ... Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ...