Fixture is a work holding and support device used in the
Fixture is used to securely locate ( position in specific
location or orientation ) and support the work, ensuring
that all parts produced using the fixture will maintain
conformity and interchangeability.
Purpose of Fixture
A fixture’s primary purpose is to create a secure mounting
point for a work piece, allowing for support during
operation and increased accuracy, precision, reliability,
and interchangeability in the finished parts.
FIXTURES MUST ALWAYS BE DESIGNED WITH
ECONOMICS IN MIND; THE PURPOSE OF THESE
DEVICES IS TO REDUCE COSTS, AND SO THEY MUST BE
DESIGNED IN SUCH A WAY THAT THE COST
REDUCTION OUTWEIGHS THE COST OF
IMPLEMENTING THE FIXTURE. IT IS USUALLY
BETTER, FROM AN ECONOMIC STANDPOINT, FOR A
FIXTURE TO RESULT IN A SMALL COST REDUCTION
FOR A PROCESS IN CONSTANT USE, THAN FOR A
LARGE COST REDUCTION FOR A PROCESS USED ONLY
Locating components ensure the geometrical stability of
the work piece . They make sure that the workpiece rests in
the correct position and orientation for the operation by
addressing and impeding all the degrees of freedom the work
For locating work pieces, fixtures employ pins (or buttons),
clamps, and surfaces. These components ensure that the
work piece is positioned correctly, and remains in the same
position throughout the operation. Surfaces provide support
for the piece, pins allow for precise location at low surface
area expense, and clamps allow for the workpiece to be
removed or its position adjusted. Locating pieces tend to be
designed and built to very tight specifications.
In designing the locating parts of a fixture, only the direction of
forces applied by the operation are considered, and not
their magnitude. Locating parts technically support the
workpiece, but do not take into account the strength of forces
applied by the process and so are usually inadequate to actually
secure the workpiece during operation. For this
purpose, support components are used.
To secure workpieces and prevent motion during operation,
support components primarily use two techniques: positive
stops and friction. A positive stop is any immovable component
(such as a solid surface or pin) that, by its placement,
physically impedes the motion of the work piece.
Manufacture a fixture to hold and support two
rectangular ( 20*10*5) work piece accurately to
drill a hole on joint .
After joining that two work piece it will be square
Remove that work piece without disturbing the
alignment of both rectangular work piece with
centered hole .
IMPORTANT CONSIDERATIONS WHILE DESIGNING JIGS
Designing of fixtures depend upon so many factors . These factors are analysed to
get design inputs for fixtures . The list of such factors is mentioned below:
Study of workpiece and finished component size and geometry .
Type and capacity of the machine, its extent of automation.
Provision of locating devices in the machine.
Available clampin arrangements in the machine
Available indexing devices, their accuracy.
Evaluation of variability in the performance results of the machine.
Rigidity and of the machine tool under consideration.
Study of ejecting devices,safety devices ,etc.
Required level of the accuracy in the work and quality to be produced.
What Should be Done…?
Collect the information regarding with Fixture ( Books
& Internet )
Paper work ( Dimensioning ) based on Problem
Search the various mechanisms for motion of Fixture.
Learn to assemble a Fixture.
Prepare the 3D model on CATIA.
Search the Materials for Manufacture .
Make a proto-type for Fixture.
Use different mechanisms to actuate the Fixture.
Actual manufacture of Fixture.
Fixture is used to securely locate ( position in
specific location or orientation ) and support the
work, ensuring that all parts produced using the
fixture will maintain conformity and
A fixture’s primary purpose is to create a secure
mounting point for a work piece, allowing for
support during operation and increased accuracy,
precision, reliability, and interchangeability in the