Vibrations From Hand-held Riveting Tools

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

AplusA-online.de - Source: National Institute for Occupational Safety and Health