Fixture Design Procedure

In the design of a fixture, a definite sequence of design stages is involved. They can
be grouped into three broad stages of design development.
Stage One deals with information gathering and analysis. These include
product analysis such as the study of design specifications, process planning,
examining the processing equipment and considering operator safety and ease of
use. In this stage, all the critical dimensions and feasible datum areas are examined
in detail.
Stage Two involves the consideration of clamping and locating schemes. A
clamping scheme is devised in such a way that it will not interfere with the tools or
cutters and are fully compatible with proposed locating surfaces or areas. The
locating scheme, using standard elements such as pins, pads, etc. is designed to be
consistent with clamping and tool-guiding arrangements.
Stage Three is the design of the structure of the fixture body frame. This is
usually built around the workpiece as a single element which links all the other
elements used for locating, clamping tool-guiding, etc. into an integral frame work.
The above procedures are quite general and can be modified depending on the
relative importance of the various elements in providing for the required accuracy
of the workpiece to be located and secured into the fixturing device. With the
popular adaptation of modular fixturing elements, the fixture body frame is usually
a standard block with fixed arrays of locating and fixing holes or slots. It becomes a
matter of selecting the most suitable body frame to accommodate the various
elements, provide good support of the workpiece and access to cutters and tools.