Introduction
The successful running of any mass production depends
upon the interchangeability to facilitate easy assembly
and reduction of unit cost. Mass production methods
demand a fast and easy method of positioning work for
accurate operations on it.
Jigs and fixtures are production tools used to
accurately manufacture duplicate and interchangeable
parts. Jigs and fixtures are specially designed so that large
numbers of components can be machined or assembled
identically, and to ensure interchangeability of
components.
JIGS
It is a work holding device that holds, supports and locates the workpiece
and guides the cutting tool for a specific operation. Jigs are usually fitted
with hardened steel bushings for guiding or other cutting tools. a jig is a
type of tool used to control the location and/or motion of another tool. A
jig's primary purpose is to provide repeatability, accuracy, and
interchangeability in the manufacturing of products. 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.
FIXTURES
It is a work holding device that holds, supports and locates the workpiece
for a specific operation but does not guide the cutting tool. It provides
only a reference surface or a device. What makes a fixture unique is that
each one is built to fit a particular part or shape. The main purpose of a
fixture is to locate and in some cases hold a workpiece during either a
machining operation or some other industrial process. A jig differs from a
fixture in that a it guides the tool to its correct position in addition to
locating and supporting the workpiece.
Examples: Vises, chucks
Advantages of Jigs and Fixtures
PRODUCTIVITY:
Jigs and fixtures increases the productivity by eliminating the
individual marking, positioning and frequent checking. The
operation time is also reduced due to increase in speed, feed
and depth of cut because of high clamping rigidity.
INTERCHANGEABILITY AND QUALITY:
Jigs and fixtures facilitate the production of articles in large
quantities with high degree of accuracy, uniform quality and
interchangeability at a competitive cost .
SKILL REDUCTION:
There is no need for skillful setting of work on tool. Jigs and
fixtures makes possible to employ unskilled or semi skilled
machine operator to make savings in labour cost.
COST REDUCTION:
Higher production, reduction in scrap, easy assembly and
savings in labour cost results in ultimate reduction in unit
cost.
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