Durability enhancement of polymer gear using compressed air cooling

Polymer gears can replace metallic gears in many engineering applications; however, thermal sensitive mechanical properties of the polymers limit its wide application. Gear tooth surface interaction as well as material hysteresis generates heat in the gear operation. There have been many attempts to improve the gear performance by design modifications as well as with new materials to withstand against thermal damages. In this work, compressed air cooling method is adopted to improve the wear resistance of injection molded polypropylene spur gears. For the chosen gear and test conditions, continuous measurement of gear surface temperature confirmed that compressed air cooling lowers the temperature up to 15?. Periodical measurement of gear tooth thickness confirms that wear resistance increases up to 100%. Continuous measurements of torque available in driver and driven end confirmed that a 2% increase in transmission efficiency of the gear pair. Test gear tooth surface after a finite number of cycles also confirms the effect of compressed air cooling on wear resistance. Mao model is used to predict the gear surface temperature and found to be in close agreement with experimental results.