A Step Ahead

Common wear parts on horizontal grinders include teeth, hammers, inserts, screens, belts and filters. These components are built to be replaced, but that doesn’t mean an operator should ignore them until it comes time to change them. Careful monitoring and management of wear parts can extend their useful lives and the life of the machine as a whole.

First, it’s important to make sure infeed material is as clean as possible. Not taking the time to do so is one of the biggest mistakes operators make when it comes to running horizontal grinders. "Dirt accelerates wear on inserts, hammers and grates," says Michael Stanton, a salesman for Morbark Inc., Winn, Mich., which makes a variety of wood processing equipment, including horizontal grinders. Not taking the time to get the rock and dirt out of the material prior to grinding will result in faster wear, Stanton says.

"Care should be taken by the operators to prevent the bulk of contaminants from entering the machine," says Mark Rieckhoff, environmental segment manager for grinder manufacturer Vermeer Corp., based in Pella, Iowa. Pushing material into a pile can lead to large quantities of dirt and sand getting mixed up in the wood debris bound for processing, he says. "If possible, depending on the application and job site, an excavator vs. a bucket loader works best to shake loose these materials before the wood goes into the grinder," Rieckhoff adds.

Manufacturers draft operators’ manuals for a reason, and ignoring the specifications in those manuals, particularly when it comes to recommended maintenance, can be a costly mistake, adds Jason Morey, grinder specialist for Bandit Industries Inc., a grinder manufacturer based in Remus, Mich. "Not maintaining horizontal grinders according to the manufacturers’ recommendations and operators’ manual is the biggest mistake an operator can make when it comes to maintaining a horizontal grinder," he says. "All maintenance and operating instructions in the operators’ manual should be followed."

Morey recommends a complete walk around the machine before operation. He also advises operators to check coolant levels and make sure the radiator debris screen is completely clean. "A partially plugged radiator will cause the engine to run at higher temperatures and may cause overheating," he says.

Stanton also advises operators to periodically check the tension on the drive belt and infeed chain.

Morey says operators’ manuals typically contain daily, weekly and monthly checklists to follow to help operators keep track of recommended preventive maintenance procedures.

"These are recommendations the manufacturer puts in place based on its machine as well as vendor knowledge of what the wear components need for lubrication and service adjustments," Rieckhoff says. "Try to avoid pushing off for another day maintenance that needs to take place today," he adds.

Rieckhoff also warns operators not to overlook the bearings when it comes to preventive maintenance. "While a lot of attention is paid to bolt or weld-in wear items, as these typically affect production rates of the machine, we can tend to forget about bearings," he says. "Lack of or improper maintenance of bearings can directly affect loss of production in downtime and repair costs."

Wear parts may seem like small items compared to the machine has a whole, but they play an integral role in its operation. Letting maintenance slip as a temporary fix or time-saver can lead to costly, long-term problems. On the other hand, staying on top of prescribed maintenance can mean big savings.

"Proper maintenance will significantly reduce operating costs," says Morey. "Teeth that are severely worn will cause the grinder to use more fuel, increasing operating costs. Belts that are not adjusted properly will cause them to wear more quickly, also increasing operating costs."

Small, regular investments of time and money can save an operation in the long run, Stanton agrees. "If a customer makes a habit of consistently checking the inserts in the hammermill, he can prevent excessive wear on the hammers, which takes a lot of money and time to replace," he says. "Basically, consistently checking an $18 part can prevent replacing a $130 part," he says.

Rieckhoff agrees that it’s better to make preventive maintenance part of a regular schedule than to wait for a machine to reach its breaking point. When a machine does break, "costly repairs that could have been avoided are now critical if the owner wishes to keep producing an end product that is sellable with the grinder, thus generating profits," he says.

Rieckhoff says horizontal grinders aren’t all that different from their human operators when it comes to maintenance. "I like to relate any machine a customer would own as the patient, and the owner or operator as the doctor," he says. "A machine can’t talk, but it can show you signs of being ‘sick.’ These symptoms come in various forms. One form might be vibration due to worn wear items and an out-of-balance drum. If not taken care of, further damage to wear parts and bearings can cause downtime and rising repair costs. Just like humans, if we ignore the symptoms our body tells us, we can shorten our lives or at a minimum, struggle until we go to see the doctor and get ‘repaired.’"