Anisotropic Shrinkage Variance in Glass-Filled Polyamide Secondary Tooling Nests
Secondary tooling nests for glass-filled polyamide accommodate anisotropic shrinkage through floating datum pins aligned with transverse contraction vectors.
Diamond Locating Pin
Meaning
Precision alignment components establish accurate part orientation in assembly fixtures and machining setups without over-constraining the workpiece. A diamond locating pin restricts rotational movement about a primary reference point while allowing dimensional variation along a secondary axis. This dual-axis positioning is essential when checking the tolerances of injection molded plastic parts that exhibit slight mold-to-mold variation.
Rotational Constraint
Using a round pin for the primary datum and a diamond locating pin for the secondary datum locks the part in place while avoiding redundant constraints. The relief on the sides of the diamond shape accommodates center-to-center distance variations between the two holes. This configuration prevents the part from binding during manual loading.
Molding Accommodation
Injection molded plastic parts frequently experience slight variations in shrinkage across different production batches. In these applications, a diamond locating pin compensates for these minor shifts in hole spacing without sacrificing alignment accuracy. This flexibility ensures that inspections remain consistent and do not reject good parts due to minor hole center variations.
Wear Resistance
Locating elements must withstand repetitive loading and unloading in high-volume molding operations. Hardened steel coatings prevent premature wear of the pin surfaces. This durability keeps the fixture accurate over many inspection cycles.