Meaning
Locating component features a relieved diameter that provides precision positioning in one axis while allowing for variation in another. Using a diamond pin in a fixture design prevents the binding that occurs when two round pins are used to locate a part. This part is typically made from hardened tool steel to resist wear over thousands of cycles.
Radial Constraint
Two-point contact at the widest part of the pin provides a solid reference for the part position. While a round pin locks the part in both x and y directions, a diamond pin allows for small changes in the distance between holes. This flexibility is essential for accommodating the natural shrinkage and thermal expansion of plastic parts.
It ensures that the part can be loaded and unloaded without force.
Positional Accuracy
Fixture builders place these components in a specific orientation to control the rotation of the workpiece. Because the diamond pin only makes contact on its narrow edges, it is less sensitive to debris or minor hole size variations. The orientation of the flats must be perpendicular to the line connecting the two locating holes.
This setup provides a robust datum for machining or inspection. High precision manufacturing relies on this simple mechanical principle to maintain tight tolerances. The use of these pins reduces the number of scrapped parts caused by fixture misalignment.
Fixture Assembly
Installation of the component requires a precision bored hole and a secure press fit. A properly maintained diamond pin ensures the longevity of the workholding tool. Regular inspection prevents the development of excessive play.
