scope:

This document describes industry accepted practices to inspect molded plastic gears. It identifies the unique characteristics of molded plastic gears that influence the accuracy and repeatability of gear measurements. This document does not establish a quality classification system or tolerances for plastic gear geometry.

This document describes the equipment commonly used in measuring plastic gears, the measurement techniques that can be employed, and statistical and system analysis issues that can be applied.

Inspection methods included in this document

The inspection methods described in this document are limited to those specifications that are typically defined on a plastic gear's drawing. These features are described in AGMA 909, Specifications for Molded Plastic Gears. Other aspects of gear quality are not considered here such as basic material strength, processing influences on strength, surface appearances, surface texture and the presence of flash.

Types of gears

Inspection methods described here are limited to the most common types of molded plastic involute gears, namely:

− spur;

− helical;

− cylindrical worm;

− external, internal, and rack forms;

− sector gears.