Day in and day out, horizontal and tub grinders are put to the test by construction and demolition (C&D) recycling professionals. Wood, recyclables and debris of all types are thrown at these machines, with the expectation that a precise finished product will come out on the other side.

Because they’re built to be tough, dependable machines, a grinder is one piece of equipment that’s only as good as its operator. Neglecting maintenance, using the wrong type of cutting tips, even disregarding safety practices all can result in a machine that operates at less than an optimum level.

Ensuring the machines are taking care of waste in a proper manner, producing a precise, uniform material, or simply that the grinder is able to keep up with a demanding project schedule are among the reasons responsible professionals should adhere to the following five tips for getting the most out of a grinder.

1. Suitable screen configuration – Several types of grinder screens are available—round or square openings, large or small screen area, added features to achieve a specific outcome and so on. To get the best results from the grinder, use the proper screen for the material being processed and the desired end product.

As a general rule of thumb, round screens are ideal when consistent finish material is the desired outcome. Conversely, square screens have more open area for higher production, making them a great choice when consistency isn’t of high concern but volume is. A demolition contractor trying to stay on a tight project deadline may favor the speed that square screens provide over the consistency of a round screen.

Finally, some screens are designed for a certain type of material, such as wet material. Further specified configurations are available with assistance from a local dealer.

2. Correct cutting tips – Similar to screen configurations, a variety of cutting tips is offered to suit different types of materials. Ensuring the proper tip is used for the material being processed is crucial to preventing issues with the finished product as well as damage to the tips.

Just as important as the material being processed is what else might be mixed in with it. Contaminants can be present in all types of material, especially in construction and demolition waste. Failure to take caution and identify contaminates can result in damage to the grinder’s cutting tips and the screens.

Wide-block tips are the most universal style and work well on wood, compost and green waste. Abrasion-resistant tips should be used when processing dirty material that could include abrasive contaminants. Additional options are offered for other specific applications.

3. Regular routine maintenance – To prepare a grinder for a tough day on the job site, it needs a little TLC. A daily maintenance checklist the operator should go through prior to starting up the machine might look something like this:

  • visually inspect grinder for anything that appears to be damaged or could interfere with operation;
  • check the engine oil level;
  • check the engine oil to be sure it’s free of contaminants; change as needed;
  • grease high-activity areas of the machine; and
  • check wear parts; replace as needed.

A smaller screen size tends to increase wear on the cutting tips, so operators who use this configuration need to replace more frequently.

A final note, many of the grinder’s wear parts can be rotated for maximized life expectancy. Depending on the machine’s hours and applications, the operator should follow a schedule for timely rotation.

4. Standard safety checks – Construction job sites are busy places, which is why it’s crucial to be aware of nearby people and equipment when operating a grinder. An operator should always put the safety of him/herself and others ahead of all else.

All operators must comply with the Occupational Safety and Health Administration (OSHA) and their employer’s regulations regarding personal protective equipment. To reduce the potential of a fire hazard, clear the machine of debris daily, taking extra care to ensure the mill bearings are free from debris. Make sure the infeed roller is clear before turning on the machine.

5. On-point operation technique – Whether a 10-year veteran of a company or a new employee, every grinder operator should receive thorough training on the machine prior to operating.

Owners, mechanics and anyone else who may work with the machine at some point should be trained on it as well. At the time of equipment setup, reputable dealerships typically provide free training.

Prior to starting the machine for the day, address all daily maintenance and safety checks. And remember: safety first. Take note of the immediate and surrounding area to ensure it’s safe to begin operation for the day.

At the end of the day, allow the machine ample time to cool down before fully shutting it off. Never attempt to do any maintenance checks of the machine, especially the engine, until it has cooled completely.

End-of-day is also prime time to address one particular area of proper machine care: grease. Not only does it save a step the next morning, equipment in general is more receptive to grease when warm and after a long day of work as opposed to the beginning of the day, prior to startup, when the machine is still cold.

More than ever, tighter timelines and increased job site demands are affecting all contractors, making optimum equipment efficiency a need, not a luxury.

By combining a small time investment with heightened awareness, every operator can get the most out of horizontal and tub grinders.

The author is recycling account manager for RDO Vermeer’s Southern California region. He can be reached at