Meaning
Injection moulding process used to manufacture high-strength mechanical gears from polyamide 66 resin. Practising pa66 gear molding requires careful thermal control because of the hygroscopic nature of the polymer and its high crystalline shrinkage. The resulting components are widely used in automotive and industrial drivetrains.
Viscosity Control
Moisture content in the polyamide 66 resin must be kept below zero point two percent prior to processing. When moisture levels are too high, the polymer undergoes hydrolysis during pa66 gear molding, which reduces molecular weight and lowers mechanical strength. Dryers are essential for maintaining stable melt viscosity, which in turn ensures that the polymer flows consistently into the thin tooth cavities of the gear mold.
Shrinkage Behavior
The high crystallinity of the material results in significant volumetric contraction as the gear cools in the mould. Moulders must balance packing pressure and injection speed to ensure uniform contraction across the tooth profile. This helps to avoid shrinkage voids.
Anisotropy Management
Fiber reinforcement is sometimes added to polyamide 66 to increase stiffness, but this induces anisotropic shrinkage during the moulding process. Fibers align along the flow direction, causing the gear to shrink unevenly and lose its roundness. Correct gate positioning helps to achieve a symmetrical flow pattern.
