Jigs and fixtures are specially designed production tools used in the manufacture of components and are used to accurately hold, support, locate and manufacture parts. They are also used to ensure the interchangeability of components so as to facilitate easy assembly and reduction of unit cost.
A type of tool used to hold, support and locate the work piece as well as to guide the movement and/or motion of another tool, jigs are divided into two general categories – drill jigs and boring jigs. Usually fitted with hardened steel drill bushings, its primary uses are to provide repeatability, accuracy, and interchangeability in the manufacturing process.
A specific type of tool used primarily in shapers, milling and slotting machine, fixtures hold, support and locate the workpiece during a machining operation or an industrial process by providing a reference surface or a device. Each fixture is unique because it is built to fit a particular part or shape.
- The locating and supporting surfaces should be replaceable and standardised to facilitate the interchangeable manufacture.
- Both jigs and fixtures should be easy clamping and unloading to reduce time wastage.
- All locating and supporting surfaces should be made from hardened materials in order to retain their precision and accuracy as well as to maintain their durability.
- Jigs and fixtures should be lightweight and be provided with adequate lift aids for ease of use, and also to not subject the workman to fatigue.
- The position of clamps should occur directly above the points supporting the workpiece to prevent distortion and springing.
- Provision should be made for proper positioning and firmly holding the jigs and fixtures. Both jigs and fixtures should remain perfectly rigid and stable during operation.
- The design of the jigs and fixtures should ensure the absolute safety of the operator at all times.
- There should be a facility to cool the jigs and fixtures as well as wash away the swarfs and chips.
- The inserts and pads should always be fastened to the faces of the clamps which will come in contact with finished surfaces of the workpiece to prevent damage.
- Proper ejecting devices should be incorporated in the body of the tools in order to push the workpiece out after the machining operation.