Pry failures are the most common and preventable failures. “The tool should not be used to scrape, drag, position, lift or pivot,” Albritton emphasizes. “It should always engage work perpendicular to the work surface, never askew.”
There are two main causes of pry failures. “The one everyone thinks of first is like a typical pry bar,” says Becker. The tool gets stuck in thick concrete. Human nature is to push or pull the tool to try to get it released. This can create a stress fracture that results in a break.
“The second pry break is where the operator is attacking the material at an improper angle, or the work dictates that the material is trimmed away while trying to stay inside a certain dimension,” says Becker. The tool skips off or alongside the material, which places side load stress on the tool.
Chipping and mushrooming of the tool are other common failures that indicate operator misuse. “Chipping is caused by working with chisels or blunt tools with a bad engagement to the work,” says Albritton. Try to ensure that the majority of the tool’s available surface area is in contact with the work. For example, a chisel should not be used on its corner, and a blunt tool should not be used on its edge. Chipping can also occur when a very cold tool is put into use without first being warmed up. A low-velocity propane torch should be used to preheat tools before use in environments less than 40° F.
Mushrooming is caused by hammering on a single location with no penetration. “The tool pulverizes the available work to dust, which then acts as a cushion, preventing the tool from transferring any energy to the work,” says Albritton. “The result is heat buildup in the tool, which can lead to overheating, softening and mushrooming. The tool should be repositioned every 15 to 30 seconds.”
Fractures also cause premature tool failure. “Fractures are caused by fatigue, damage or both,” says Albritton. “As the tool becomes galled and scarred from use, the likelihood of fatigue crack propagation and tool failure increases. A fatigue crack is caused by a disruption of the energy traveling through the tool. This will typically look like it was cut almost straight across. There will be a chevron where the crack initiated and there may be a slight lip on the final side to fail.”
A fatigue crack can be caused by inadequate/incorrect lubrication, which causes frictional burning or welding of the tool to the bushing. “This creates the nicks and gouges where these cracks occur,” says Albritton. “One of the best ways to prevent this is correct lubrication. Check the bushing regularly and replace if worn. Do not re-insert a worn and galled tool in a new bushing or a brand new tool in a worn and galled bushing. Never weld on a tool for any reason.”
Dry firing a tool against the retainer pin in the hammer creates failures in the retainer slot area. “Keep the tool properly engaged with the work and limit unproductive piston strokes,” says Albritton. “Check retainer pins regularly and replace if worn, damaged or deformed.” Also prevent side loading or twisting the tool.