DESIGN OF JIGS
· 1. Introduction
o
Objectives
· 2. Design of Jigs
·
3. Elements of
Jig
o
Design Consideration in Jigs
o
Presentation of Workpiece
o
Location
o
Principles of Location
o
Location Methods
o
Clamping
o
Drill Bushes
o
Jig Feet and Legs
o
Chip Control
·
4. Types of Jig and Examples
1. INTRODUCTION
Mass production targets on increasing productivity and increasing accuracy by reducing
the setup cost and manual fatigue.
One of the common practices to achieve the goals of mass production is to use jigs. Let us consider an example that one gets an order of 1000
product in such a way that three holes are to be drilled
in a workpiece. In such situations, designer will lay out the position
of each hole with the help of square, straightness, scribers, centre
punch etc. Generally, trial and error method is practiced until the axis of
hole is properly aligned with the axis of drill. Thus, a
lot of time will be consumed to
maintain the accuracy. Ultimately
it increases operator’s fatigue. Thus,
instead of laying
out the position of each hole on each workpiece
with the aid of square,
straightness, scribers, centre punch
etc., the operator
uses a jig to position and guide the drill into
proper place. Drill jig increases productivity by eliminating individual marking, positioning and frequent checking. Interchangeability is one of the advantages of jigs. There is no need for selective assembly. Any of the parts will fit properly in the assembly
and all similar components
are interchangeable. In addition,
a jig reduces the repetitive
nature required for drilling a hole,
as the locating, clamping and guiding
are done by jig itself. The tool-guiding element helps
in setting of tool in correct position. Hence, skilled workers are not required. Drill jig makes it
possible to drill, ream and tap holes
at much faster speed and with great accuracy as compared to holes produced by conventional.
Jig can
be defined as a
workpiece holding and locating device that positions and guides or controls the cutting tool.
Drill jig is device to ensure a hole
to be drilled, tapped or reamed in the workpiece at proper place.
Drill jig consists
of a clamping device to hold the part in the position
under hardened steel bushings. Drill passes through
the steel bushings during drilling operation. The drill is guided
by these bushings. Generally
workpiece is held by
jig and the jig is arranged in such
a way that the workpiece can be quickly
loaded and unloaded.
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