Keep Grinders at Peak Performance

If you're looking to increase the productivity of your grinding operation, your initial reaction might be to upgrade to a higher horsepower machine so you can grind more product, more quickly. In the end, that may be exactly what you need. But you should first evaluate your maintenance program to ensure you're getting the most out of your existing equipment.

A poorly maintained grinder is less efficient, says Jason Morey, marketing, Bandit Industries. "When components such as teeth aren't maintained, the engine has to work a lot harder," he says. "It just takes more horsepower to grind with damaged teeth."

Dull, damaged and/or improperly rotated teeth can also become unbalanced, which can lead to excessive vibration, notes Mike Adsit, service manager, Morbark. "The hammermill is the heart of your machine," he explains. "If it gets out of balance and starts to vibrate, it will cause other problems. You will start to find cracks, and other components will start to fail. You can also have electrical issues."

Given the demanding tasks placed on a grinder every day - devouring everything from root balls with clods of dirt and small stones, to construction debris interlaced with metal and steel - components can quickly become damaged. If that damage goes undetected for an extended period of time, the end result is downtime and costly repairs.

To keep your grinders in peak operating condition, implement a preventive maintenance program that focuses on inspections that can alert you to damaged/worn components early. Manufacturers typically provide maintenance manuals that outline a timeline for when each component should be inspected.

"We want our customers to be familiar with maintenance tasks so they will have less downtime, and a lower cost of operation," says Jay Sarver, service manager, Vermeer.

Inspect prior to operation
Start with a visual walkaround of the entire machine prior to operation each day, suggests Sarver. This will alert you to problems with the machine, as well as any potential problems with jobsite conditions.

Look at conveyor belt tracking and infeed chains. In Vermeer tub grinders, pay special attention to the Duplex Drum, which performs the grinding. "Inspect the drum and cutter blocks," says Sarver. "The Duplex Drum is the money maker on the machine, but it could be a hole in your pocket if maintenance is not taken care of."

Teeth (inserts) are a wear item in any grinder, notes John Foote, vice president, sales and marketing, Morbark. "Those inserts are what pound against the material and grind it," he adds. "They receive all the wear."

Visually inspect the teeth and replace them as needed. "Check them in the morning, at lunch and then again at the end of the day," says Adsit. "And don't let them wear down to the point where you start to see wear on the hammer. If that happens, it's a costly repair."

Typically, teeth are made of tungsten carbide and are boltable to the hammer, so they can be easily replaced. To facilitate changeout in the field, many grinder manufacturers offer models equipped with an air compressor and all the necessary equipment to change teeth on site.

Maintain fluids and filters
Pay attention to greasing schedules for bearings for the cutter mill/hammermill, conveyor and infeed, as well as other components that rotate regularly.

In addition, check filters (fuel, hydraulic, etc.) routinely. "If you don't change the hydraulic filter when necessary, it can go into bypass mode, which allows contamination back into the tank," says Adsit. "Contamination is the biggest enemy of hydraulics. It doesn't take much dirt for hydraulic components to start to wear, or for the flow of oil to be blocked. That can create heat and fatigue the rest of the components."

Belt tension can be an issue in new machines, Morey notes. "Belts generally stretch when they're new," he explains, adding that Bandit horizontal grinders use Kevlar belts to cut maintenance costs. Check belt tension of a new machine at two hours of initial operation, then check it weekly. A properly adjusted belt will keep the grinder working longer, while reducing operating expense.