Wear Resistance Testing
The wear resistance of a casting is generally most affected by the composition of the alloy from which it is made and to a lesser extent by the casting process. As a result prototypes for wear resistance testing should be made from the alloy intended for the production part. The wear resistance of zinc alloys varies from moderate to excellent depending upon factors such as loading, sliding speed, the material against which it is rubbing and the lubrication conditions. Generally zinc alloys perform best against hard surfaces such as steel and less well against soft materials such as nylon. ZL12 and ZL27 have excellent low speed bearing properties and are not infrequently used in replacement for bronzes in heavy engineering applications, running against steel surfaces. One consequence of this is that wear testing of ZL12 or ZL27 alloy prototypes, intended for eventual production in alloy 3 or 5 will generally give over optimistic results. It is best to perform any tests at the maximum intended service temperature for the part.