This information sheet provides descriptions of plastic materials commonly used in gearing. It relates the general properties of these materials to typical operating conditions of gears. Properties that relate to the manufacturing processes of machining and molding are discussed@ including the property of shrink rate in molding. It also describes the types of tests that are customarily used to obtain published values of these properties. It is intended that this information sheet serve only as an introductory guide to the designer of plastic gears when it comes to selecting candidate materials. The designer is advised to look to material suppliers and plastic gear manufacturers for their expert guidance on selecting materials for specific applications. It is also important to recognize that thorough application testing is often needed to confirm the suitability of a material choice. Only a limited number of plastic materials are mentioned here as commonly used for gears. Gears have been made from other plastics as well@ but generally because some special material property or commercial consideration was judged essential to a particular application. It is also possible that the suitability of other materials for gears has not yet been recognized. Furthermore@ new plastic materials are continually being developed and some@ no doubt@ will prove themselves as important additions to those discussed in this information sheet.