Learn how to use a wood chipper without ending up in the ER.
Wood chippers show up in horror movies because of just how powerful they are. Their ability to turn large tree limbs into small chips is truly impressive. But accidents are common. The pull of a chipper can cause serious injury and even death. Whether you’re using one for the first time or you’ve used many times before, brushing up on wood chipper safety best practices can help you keep all your fingers and limbs intact.
How does a wood chipper work?
A wood chipper, as its name implies, is a machine that transforms tree limbs, branches and trunks into chips. A powerful engine turns a rotating drum set with blades or “knives” that cut the wood.
The combination of speed and torque allows commercial wood chippers to pull in branches at 20 inches per second. As an operator manually pushes brush and tree limbs through the infeed chute or hopper collar into the hopper, the feed mechanism and drum blades grab anything within reach. “Anything” can include long hair, loose jewelry, rope, an arm or fingers.
How common are wood chipper accidents?
Statistics tell a sobering story. Five workers died in chipper-related accidents in 2020, and two died in 2019, OSHA accident records show. Most fatalities result from being caught in the chipper; a smaller number occur when an object kicks back from a chipper and strikes the operator.
How to use a wood chipper the safe way
To avoid accidents, follow these best practices for safe wood chipper operation.
- Wear the right safety gear. Anyone working near a wood chipper should wear eye and hearing protection, close-fitting clothing and a hard hat or helmet. Wear pants and gloves that don’t have cuffs. Steel-toed work boots with skid-resistant soles can prevent slips near the infeed chute and protect your feet. Leave the jewelry and anything dangly at home. If you have long hair or a beard, tie it up or tuck it away.
- Know the machine. Before using a wood chipper, read the operating manual. Familiarize yourself with the machine, its safety controls and proper start-up and shut-down procedures. Know how to stop or reverse the machine in case of an emergency before you turn it on.
- Inspect it before each use or at the start of each shift. The disc hood should be closed and latched. Check the infeed chute for foreign objects. Make sure bolts and pins are tight. (Every chipper manufacturer specifies torque levels for the knife bolts and nuts.) Inspect the knives for wear or damage. Running the chipper with worn or damaged knives can cause the feed to clog and eventually kick debris back through the infeed chute.
- Check the guards. Make sure they’re not missing. Many chipper accident reports cite the absence of guards or malfunctioning safety devices. OSHA’s general machine guarding standard 29 CFR 1910.212 (a)(1) requires that chippers have one or more guards to protect workers from rotating parts and flying debris.
- Point the discharge chute away from people and traffic. This one’s obvious but still worth mentioning.
- Designate someone to stand near the emergency shut-off switch when the machine is in operation. A worker caught in a commercial wood chipper can’t reach a safety device. Never work alone with a wood chipper.
- Check tree debris before feeding it into the chipper to make sure it doesn’t contain foreign objects. Never throw other materials into the machine.
- Stay free and clear as you feed.OSHA’s Chipper/Shredder Safety Manual recommends standing to the side of the infeed chute, pushing materials in with a wooden push tool or long branch, feeding branches in butt-end first and placing shorter branches on top of longer ones.
- Limit the size of the pieces you insert. Don’t feed the machine material that’s larger than it’s rated for. Industrial chippers are capable of cutting wood from 6 inches in diameter to 12 inches in diameter, so study your worksite before choosing your machine. Put small debris in the trash, not in the chipper.
- Immobilize the disc or roller. Do this before clearing a chute or changing the chipper blades.
Wood chipper manufacturers have introduced a variety of engineering controls designed to increase the safety of these machines. They include feed tray extensions, rubber curtains in front of the infeed chute, feed control bars that stop or reverse feed rollers, pressure-sensitive bottom feed stop bars, panic bars that stop the hydraulic system that operates the feed rollers, and emergency pull ropes that allow operators to reverse feed rollers. Remember, however, that engineering controls are never a substitute for safe work practices and commonsense precautions.
Chipper accidents are rarely minor. Amputations can happen in less than half a second. To avoid a horror story scenario, never become complacent.
John Ross has written about industrial, automotive and consumer technologies for 17 years.