Annals of Occupational Hygiene Advance Access first published online on January 22, 2008
This version published online on February 8, 2008
Annals of Occupational Hygiene, doi:10.1093/annhyg/mem064
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An Evaluation of Impact Wrench Vibration Emissions and Test Methods
National Institute for Occupational Safety and Health (NIOSH), NIOSH Health Effects Lab, 1095 Willowdale Road, Morgantown, WV 26505, USA
* Author to whom correspondence should be addressed. Tel: +304-285-6337; fax: +304-285-6265; e-mail: tmcdowell{at}cdc.gov
In the interest of providing more effective evaluations of impact wrench vibration exposures and the development of improved methods for measuring vibration emissions produced by these tools, this study focused on three variables: acceleration measured at the tool surface, vibration exposure duration per test trial, and the amount of torque required to unseat the nuts following a test trial. For this evaluation, six experienced male impact wrench operators used three samples each of five impact wrench models (four pneumatic models and one battery-powered model) in a simulated work task. The test setup and procedures were based on those provided by an International Organization for Standardization (ISO) Technical Committee overseeing the revision of ISO 8662-7. The work task involved the seating of 10 nuts onto 10 bolts mounted on steel plates. The results indicate that acceleration magnitudes vary not only by tool type but also by individual tools within a type. Thus, evaluators are cautioned against drawing conclusions based on small numbers of tools and/or tool operators. Appropriate sample sizes are suggested. It was further noted that evaluators could draw different conclusions if tool assessments are based on ISO-weighted acceleration as opposed to unweighted acceleration. As expected, vibration exposure durations varied by tool type and by test subject; duration means varied more for study participants than they did for tool types. For the 12 pneumatic tools evaluated in this study, torque varied directly with tool handle acceleration. Therefore, in order to reduce vibration exposure, tools should be selected and adjusted so that they produce no more than the needed torque for the task at hand.
exposure assessment • HAVS • impact wrench • vibration
Received August 16, 2007; in final form October 31, 2007
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  T. W. McDowell, P. Marcotte, C. Warren, D. E. Welcome, and R. G. Dong Comparing Three Methods for Evaluating Impact Wrench Vibration Emissions Ann. Hyg., August 1, 2009; 53(6): 617 - 626. [Abstract] [Full Text] [PDF]
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