PA6 (Polyamide 6)
Semi-crystalline technopolymer with good wear and impact resistance. Hygroscopic: absorbs moisture from the environment, which affects both dimensions and mechanical properties. Must be accounted for during backlash design.
Technical Reference
Technical Gear Glossary
Definitions of the main technical terms used in motion transmission with technopolymer gears.
P
Paper trick
Empirical method for verifying contact in a bevel gear pair: a thin sheet of paper is interposed between the teeth to reveal the contact zone and its distribution. Useful during assembly and adjustment.
Pitch diameter
Diameter of the theoretical circle at which contact occurs between two meshing gears. Obtained from the product of the module and the number of teeth.
Pitting
Form of surface wear caused by contact fatigue. It manifests as micro-craters on tooth flanks resulting from cyclic Hertzian contact stress.
Polyketone (PK)
Semi-crystalline technopolymer with a very low friction coefficient and high chemical resistance. An alternative to POM in environments involving aggressive lubricants or fuels.
POM (Acetal resin / Polyoxymethylene)
Semi-crystalline technopolymer with high rigidity, low friction coefficient and good dimensional stability. Recommended for gears operating dry or with minimal lubrication. Sensitive to strong acids and temperatures above 90–100 °C.
Pressure angle
Angle between the direction of the contact force between mating teeth and the tangent to the pitch circle at the point of contact. The standard value is 20°.