Design of JIGS

Mass production targets on enhancing productivity and enhancing accuracy by reducing the setup cost and manual fatigue. One of the common practices to obtain the goals of mass production is to use jigs. Let us assume an instance that one gets an order of 1000 product in such a way that three holes are to be drilled in a workpiece. In such condition, designer will lay out the position of each hole with the help of, straightness, square, centre punch scribers etc. In general, trial and error method is practiced until the axis of hole is appropriately aligned with the axis of drill. Therefore, a lot of time will be consumed to maintain the accuracy. Finally it increases operator's fatigue. Therefore, rather than laying out the position of each hole on each workpiece with the aid of square, , scribers, straightness centre punch so on., the operator uses a jig to position and guide the drill into correct place. Drill jig enhance productivity by eliminating individual marking, positioning and frequent checking. Interchange ability is one of the rewards of jigs. There is no need for selective assembly. Any of the parts will properly fit in the assembly and all similar components are interchangeable. Additionally, a jig reduces the repetitive nature required for drilling a hole, as the clamping, locating and guiding are done by jig itself. The tool-guiding element helps in setting of tool in correct position.

Therefore, skilled workers are not required. Drill jig makes it possible to ream, drill and tap holes at much faster speed and with great accuracy as compared to holes generated by conventional hand technique. The responsibility for accuracy of hole location is taken from the operator and given to the jig. Jig can be described as a workpiece holding and locating device that positions and guides or controls the cutting tool. Drill jig is device to make sure a hole to be tapped, drilled or reamed in the workpiece at proper place. Drill jig contain a clamping device to hold the part in the position under hardened steel bushings. Drill passes out through the steel bushings during drilling operation. The drill is guided by these bushings. In general workpiece is held by jig and the jig is arranged in such a way that the workpiece can be rapidly loaded and unloaded.

Objectives

After studying this unit, you should be able to

• Know different kind of locating elements,
• Know different kind of clamping elements,
• Know different type of guiding elements,
• Design many types of jigs, and
• Differentiate various types of jigs.