Risk of injuries and disorders to the blood vessels, nerves, muscles, and bones of the hands from Vibrations From Hand-held Riveting Tools

New Laboratory Method Evaluates Vibrations From Hand-held Riveting Tools

Scientists developed an apparatus and a laboratory-based methodology to simulate a riveting task to measure bucking bar vibrations. Photo from NIOSH.

When considering aircraft worker safety, the most visible jobs—pilot, air traffic controller, security screener—often come to mind. In truth, however, worker safety begins long before takeoff. During aircraft construction and maintenance, workers attach layers of sheet metal to airframes using hand-held tools called bucking bars. Used with air-powered riveting hammers, bucking bars enable workers to set rivets into predrilled holes in aircraft and other products. The problem is that bucking bars, like most powered hand tools, transmit vibrations, which increase the risk of injuries and disorders to the blood vessels, nerves, muscles, and bones of the hands. Although manufacturers have introduced new types of bucking bars designed to reduce risk, their effectiveness is unclear because there is no standardized method to measure their transmitted vibrations.
Recognizing this need, scientists at the National Institute for Occupational Safety and Health (NIOSH) recently developed and tested a lab-based riveting simulator that mimics the conditions observed during actual riveting tasks. The riveting simulator delivers reliable and repeatable forces to a bucking bar when measuring vibrations transmitted to the hand. With this new apparatus and laboratory method, NIOSH scientists evaluated three traditional steel rivet bucking bars and six newer bucking bars. Specifically, the newer designs included three bucking bars made from tungsten and three bucking bars with a mechanism designed to decrease vibrations. To compare to typical riveting tasks, the scientists also tested the bucking bars during three such tasks at a large aircraft maintenance facility.
They found that the laboratory method was able to identify which bucking bars would transmit the lowest exposure of vibrations to workers at the maintenance facility. They also observed that the newer bucking bars had significantly reduced vibrations compared to the traditional bucking bars. Vibration measurements in the laboratory, however, were considerably lower than the measurements produced in the maintenance facility. These findings suggest that the laboratory method is an acceptable way to compare and screen bucking bars but not to measure the risk of exposure to transmitted vibrations in the workplace. Next, the scientists plan to refine the laboratory method to better simulate actual riveting tasks and, ultimately, develop a standardized test for workplace exposure to bucking bar vibrations.
More information is available:

• Laboratory and Workplace Assessments of Rivet Bucking Bar Vibration Emissions