Experimental Evaluation of Semi-Aromatic Polyamides as a Gear Material

Abstract

Remarkable improvements in load capacity and transmission error have recently expanded the application fields of plastic gears. POM is one of the most suitable materials for them but has a limit on working temperature. Although PA46 has good mechanical properties even under relatively high temperatures, it also has high water absorbency. The water absorption changes the micro geometries of teeth and decreases the strength, which limits the application fields of PA46. The present study describes a semi-aromatic polyamide as a novel candidate for gear materials. It also has superior mechanical properties under high temperatures but shows little water absorption. Running tests following JIS B 1759, which specifies the calculation method of cylindrical-gear load capacity, examined gears of various semi-aromatic polyamides, which include modifiers and fortifiers. The results showed that a semi-aromatic polyamide could be suitable for gear material, including a proper modifier and fortifier. Further running tests will define applications in which semi-aromatic polyamides have more advantages than other plastics.