EXPECTATION REGARDING HIGHER LOAD CAPACITY OF LONG-FIBER-REINFORCED PLASTIC GEAR PAIRS

Abstract

To be improved their strengths and stiffnesses, some plastic materials are reinforced with fibers. However, even such fiber-reinforced plastics have never obtained sufficient strengths for power transmission gear pairs. Generally, fibers of the reinforcement are 0.1 mm long, so that they could not entwine. Meanwhile, much longer fibers have been launched for plastic reinforcement. They are some mm long, so that such longer fibers could entwine as fluff balls, and could form 3-dimensional networks in parts. This could enables higher strengths and stiffnesses to be achieved. The present paper describes gear running tests for evaluating load capacity of long-fiber-reinforced PA66 gear pairs. In addition, observations of fiber distributions in injection-molded gears with an X-ray CT scanning causes molding conditions to be improved. As a results, some lubricants yielded much higher load capacities of long fiber-reinforced PA66 gear pairs than those of usual-fiber-reinforced ones. In this paper, only 33 weight percent glass fibers were discussed, but 60 weight percent ones are also available. They might be expected to show much higher load capacities of gear pairs.