A jig is a type of custom-made tool used to control the location and/or motion of parts or other tools. A jig's primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products. A jig is often confused with a fixture; a fixture holds the work in a fixed location. A device that does both functions (holding the work and guiding a tool) is called a jig.
An example of a jig is when a key is duplicated; the original is used as a jig so the new key can have the same path as the old one. Since the advent of automation and computer numerical controlled (CNC) machines, jigs are often not required because the tool path is digitally programmed and stored in memory. Jigs may be made for reforming plastics.
Jigs or templates have been known long before the industrial age. There are many types of jigs, and each one is custom-tailored to do a specific job.
A fixture is a work-holding or support device used in the manufacturing industry. Fixtures are used to securely locate (position in a specific location or orientation) and support the work, ensuring that all parts produced using the fixture will maintain conformity and interchangeability. Using a fixture improves the economy of production by allowing smooth operation and quick transition from part to part, reducing the requirement for skilled labor by simplifying how workpieces are mounted, and increasing conformity across a production run.
A fixture differs from a jig in that when a fixture is used, the tool must move relative to the workpiece; a jig moves the piece while the tool remains stationary.
Precision Machining is a process to remove material from a workpiece during holding close tolerance finishes. The precision machine has many types, including milling, turning and electrical discharge machining. A precision machine today is generally controlled using a Computer Numerical Controls (CNC).
Precision machining contributes parts and pieces from space shuttle pencils. Almost all metal products use precision machining, as do many other materials such as plastic and wood. These machines are operated by specialized and trained machinists. In order for the cutting tool to do its job, it must be moved in directions specified to make the correct cut. This primary motion is called the “cutting speed.” The workpiece can also be moved, known as the secondary motion of “feed.” Together, these motions and the sharpness of the cutting tool allow the precision machine to operate.