Solution Summary: Large Striking Cap Chisels
Large striking cap chisels is an engineering control used to reduce musculoskeletal disorders (MSD) from hand-arm vibration as well as striking injuries. These chisels have cushioned grips and larger striking surface areas.
There are different kinds of large striking cap chisels available from various manufacturers.
Hard Cap® Safety Chisels are available for wood, masonry, brick, cold, and flooring (Figure 1). Hard Cap® punches are also available and come in a variety of sizes. The tools are designed with shatter-resistant polymer caps which provide a larger striking surface area. They also have oil-resistant cushioned grips to reduce vibration and force to the hand and wrist.
Figure 1. Hard Cap® Safety Chisels and punches
Stanley FatMax® Chisels are available for brick, masonry, concrete, cold, flooring and for electricians (Figure 2). FatMax® Chisels have bi-material hand guards to provide a large surface area and reduce vibration.
Figure 2. Stanely FatMax® Mason's Chisel with Bi-Material Hand Guard
Striking chisels can cause musculoskeletal disorders (MSD) from hand-arm vibration and traumatic hand injuries from missing the chisel head. Hand-arm vibration can cause MSDs such as muscle strains; tendonitis, which is inflammation of elbow and wrist tendons; or carpal tunnel syndrome, which is compression of a wrist nerve, resulting in finger numbness and loss of hand strength. The cushion from the large striking cap chisels, such as the Hard Cap® Safety Chisels, can absorb the vibration to reduce the risk of hand-arm vibration. The large striking surface can also reduce the likelihood of missing the chisel head when striking down. Large striking cap chisels also eliminate flying metal fragments and chisel head mushrooming (rounding and flaring of the striking surface).
How Risks are Reduced:
The Hard Cap® Safety Chisel’s polymer cap reduces the risk of injury by decreasing vibration felt by the striking hand, decreasing the noise transmitted from striking the chisel, and decreasing the chance of missing the chisel head and hitting the operator’s hand. It also eliminates flying metal fragments and chisel head mushrooming (rounding and flaring of the striking surface).
The cushioned grip reduces risk of injury by decreasing vibration felt by the stabilizing hand. The cushioned grip also decreases the amount of contact stress experienced by the worker and increases worker control of the tool.
The addition of a polymer cap and cushioned grip to chisels has many benefits. Independent published studies have shown significant decreases in both vibration and noise when using the Hard Cap® Safety Chisel. Hand-arm vibration measurements revealed a 20% reduction at the hand/handle junction when using a capped striking device vs. a traditional striking device. Significant reductions were also found in sound transmission, and the workers participating in the study confirmed a decrease in noise. Repeated testing of the Hard Cap® Safety Chisel showed reductions in chisel head degeneration when compared to traditional chisels.
- Unbreakable, tough reinforced polymer cap
- Comfort grip reduces vibration by up to 90%
- Noise level reduced by up to 80%
- Striking surface is 2½ times larger
- Eliminated flying chips and mushrooming of chisel heads
Effects on Productivity:
Large striking cap chisels increase productivity due to an increase in user confidence and harder hitting capability.
Metal chisels may become difficult to grip if oil and grease builds up on the grip surface. However, the cushioned grip is made of material that is resistant to oil and grease. A worker is less likely to have their hand slip when gripping the cushioned grip surface.
Dan Anton, PT, PhD, ATC; Jesse Brouwer, SPT, and Cassie Malecha, DPT – Eastern Washington University