Modeling and Testing of a New Polymer-Based Impact Tool Design to Reduce Noise, Vibration and Biomechanical Injuries

A new power impact tool design has been developed and tested using advanced engineering polymers to replace traditional metal components. The new polymer-metal impact mechanism generates less noise, lower vibrations, and potentially reduces biomechanical injuries. Power tools are known to cause several medical ailments including Hand-Arm Vibration Syndrome (HAV), Raynaud's phenomenon, and Vibration White Finger unless the daily exposure and/or dosage is limited. To evaluate the effects of a polymer-metal impact mechanism on tool performance, a non-linear model describing the equations of motion and resulting output forces were developed. In addition, a number of experiments with a high frequency Instron test machine and prototype tools were performed to validate the model and compare performance of conventional power tools to the new polymer based design. The results show that although adding a polymer does reduce noise and vibration, the reduction in impact force is relatively small and statistically insignificant. Various polymer materials and shapes were evaluated and results show that for durability and performance, the optimum appears to be a plug inserted in a cavity in either the piston or the cutting tool, thus creating a state of confined compression on the polymer. The polymer used in this research was Minlon® (mineral reinforced Nylon66), and durability was improved when the polymer inserts were cycled with compressive loads before use in the power tool.Copyright © 2006 by ASME