Laboratory and field measurements and evaluations of vibration at the handles of riveting hammers

Abstract

The use of riveting hammers can expose workers to harmful levels of hand-transmitted vibration (HTV). As a part of efforts to reduce HTV exposures through tool selection, the primary objective of this study was to evaluate the applicability of a standardized laboratory-based riveting hammer assessment protocol for screening riveting hammers. The second objective was to characterize the vibration emissions of reduced vibration riveting hammers and to make approximations of the HTV exposures of workers operating these tools in actual work tasks. Eight pneumatic riveting hammers were selected for the study. They were first assessed in a laboratory using the standardized method for measuring vibration emissions at the tool handle. The tools were then further assessed under actual working conditions during three aircraft sheet metal riveting tasks. Although the average vibration magnitudes of the riveting hammers measured in the laboratory test were considerably different from those measured in the field study, the rank orders of the tools determined via these tests were fairly consistent, especially for the lower vibration tools. This study identified four tools that consistently exhibited lower frequency-weighted and unweighted accelerations in both the laboratory and workplace evaluations. These observations suggest that the standardized riveting hammer test is acceptable for identifying tools that could be expected to exhibit lower vibrations in workplace environments. However, the large differences between the accelerations measured in the laboratory and field suggest that the standardized laboratory-based tool assessment is not suitable for estimating workplace riveting hammer HTV exposures. Based on the frequency-weighted accelerations measured at the tool handles during the three work tasks, the sheet metal mechanics assigned to these tasks at the studied workplace are unlikely to exceed the daily vibration exposure action value (2.5 m s(-2)) using any of the evaluated riveting hammers.

Laboratory and Workplace Assessments of Rivet Bucking Bar Vibration Emissions

“…The workplace riveting hammer acceleration averages were considerably higher in the present study than those observed in our earlier riveting hammer study at the aircraft maintenance facility (McDowell et al .,2012). While the same riveting tasks were evaluated in both studies, the riveting hammer vibration measurements are not directly comparable because the studies employed different riveting tools and different operators.…”

“…Similar to the ISO standards, the proposed apparatus and procedure are designed to deliver consistent forces and excitation to selected bucking bars while the vibration transmitted to the hand-tool interface is measured. The proposed test method was also designed to provide reasonable representations of the postures, applied forces, and vibration excitations observed in actual riveting tasks like those evaluated during the earlier riveting hammer study (McDowell et al ., 2012). (For a more detailed discussion about the development of the NIOSH bucking bar test apparatus, see the Supplementary data available at Annals of Occupational Hygiene online.…”

“…These were the same three riveting tasks assessed in the earlier riveting hammer study (McDowell et al ., 2012). All three tasks involved riveting the sheet metal ‘skins’ to the ‘ribs’ of the airframes.…”

“…Despite new developments in robotics and other technologies, this manual riveting process remains the predominant method for fastening sheet metal to airframes (Jorgensen and Viswanathan, 2005; Cheraghi, 2008). It has been demonstrated that pneumatic riveting hammers can generate high magnitudes of impulsive vibrations (Dandanell and Engstrorn, 1986; Burdorf and Monster, 1991; McDowell et al ., 2012). These vibrations can be effectively transmitted to the hands and fingers of the riveting hammer and bucking bar operators (Kattel and Fernandez, 1999).…”

“…For example, Part 10 of this series (ISO, 2011) pertains specifically to chipping hammers and riveting hammers. Recently, we completed a study which utilized the ISO 28927-10 standard as part of their evaluation of a number of riveting hammers (McDowell et al ., 2012). That study found that while the ISO laboratory-based standardized method is not suitable for estimating workplace HTV exposure levels, the ISO method is acceptable for identifying riveting hammers that could be expected to exhibit lower vibrations in workplace environments.…”