1. Stationary Checking Fixture

It is a stationary fixture that consists of a frame that is present on a floor or a table and the part to be inspected is brought and mounted on it. Once the part is positioned properly on a fixture frame, the other gauging devices are employed. These gauging components may or may not be attached to the frame. Sometimes the frame may have the structure to hold the part and the series of checking surfaces are placed at some distance from the part. A feeler gauge is inserted between the part and the check surface to confirm the correct shape of the part.

2. Apply-Type Checking Fixture

The Apply-type checking Fixture operates exactly opposite to the standard checking ones. These fixtures are loaded onto the larger parts or assemblies and inspected for the dimensional and profile accuracy of the parts. Some heavier parts, automobile components, in particular, can’t be placed on a fixture. But all the differences in accuracy can lead to product failure costing thousands of dollars. The apply-type fixture does the work in such cases. They are carried to desired locations and loaded onto the parts that are to be measured for accuracy.

3. Coordinate Measuring Machine (CMM) Fixture

A Coordinate Measuring Machine (CMM) is a measuring device to inspects the physical geometry of an object by sensing discrete points on the surface of the object or a part using a sensing probe. When the probe touches a surface, the transducer records the input and sends it as an electric impulse to the computer.

The computer then interprets the signal and registers its location in space. The points are recorded in terms of (X, Y, Z)  with X, Y, and Z being distances of each point in X, Y, and Z directions from the origin (0,0,0) using a cartesian coordinate system. The CMM fixture is made to hold the work part in the exact position as in actual operation. A known point in space is located on the fixture or on the part to be inspected and the CMM is located relative to that point. It starts to inspect other points on the workpiece to determine their locations. The dimensional and positional accuracy of the complex and intricate shaped parts or sub-assemblies can be measured using the CMM fixture.

4. Progressive Inspection Metal Match(PIMM) Fixture

While manufacturers have other fixtures to inspect an automobile’s parts, they are not suitable for checking a newly designed car or its prototype. To avoid such a blunder, the PIMM fixtures are used. These fixtures confirm whether all the sheet metal parts of the assembly fit together in the prototype stage itself. The PIMM fixture comes with a huge frame, a series of locators to mount the panels, and a clamp to hold the panels in position.

Each prototype panel is placed on its locators and positioned using clamps. This is repeated until the entire side of the vehicle is made up virtually. All of them should fit on the fixture accurately. Inspect the fits and clearances with the feeler gauge and check for any misfits or errors. If everything sits well, then the parts are within acceptable limits.