Grinding Safeguards

| |
Construction Safety Association of Ontario

Summary Statement

Describes safety hazards using grinders, PPE that should be worn and steps that can be taken to reduce hazards.
Spring 2000

Secure or remove any loose clothing that might get caught.

Grinders come in bench and portable types. Common causes of injury on grinders are

  • grinding wheels flying apart
  • hands touching the wheel
  • work getting hot and burning fingers
  • sparks and grindings
  • work pulled into the wheel.
Personal Protective Equipment

  • When operating grinders, always wear proper eye protection. A face shield is also recommended.
  • Respiratory protection suited to particular dust hazards may be required. Use hearing protection.
  • Wear gloves and aprons where hot sparks are being generated

Bench Grinders

Bench grinders are designed for jobs such as removing excess metal and smoothing metal surfaces. The grinders are usually fitted with both a medium grain and a fine grain abrasive wheel. When a considerable quantity of metal is to be removed, it's often more practical to grind with the medium wheel first and finish up with the fine wheel. A tool rest at the front of each wheel guides the work during grinding.


  • Before grinding, check the wheel for cracks or chips and replace if necessary. Use the ring test (see box).
  • Remove any flammable material from the work area. Sparks can cause fire or explosion.
  • Secure or remove any loose clothing that might get caught in the grinder.
  • Adjust the tool rest so that it just clears the wheel and is above the wheel's center line. This keeps work from jamming between tool rest and wheel.
  • Never adjust the tool rest while the wheel is turning.
  • Before starting, make sure guards are in place and working properly.
  • Stand to one side, turn on the grinder, and let the machine come up to full speed. There's always a chance a wheel may break up and fly apart.
  • Never force work against a cold wheel. Apply work gradually to give the wheel time to warm up.
  • Always keep the work moving across the face of the wheel. This prevents grooves from being worn into the wheel.
  • Never grind on the side of the wheel. Side pressure can break wheels not designed for that use.
  • Maintain good footing. Floor may become slippery with grindings.
  • Keep guards in place during operation.

Replacing wheels

  • Follow manufacturer's instructions.
  • Unplug the tool.
  • Use the proper hardware--safety flanges, nuts, blotters--to hold wheels in position.
  • Always check the speed rating on the wheel and on the grinder to make sure that both are compatible.
  • Tighten the spindle nut just enough to hold the wheel. Too tight and you may damage the wheel.

Ring Test

  • Clean material from grinding wheel.
  • Let wheel dry before testing.
  • Tap wheel with something nonmetallic such as a screwdriver handle.
  • Tap 1/2 inch from outside rim.
  • Rotate wheel 45 degrees and repeat test.
  • A sound, undamaged wheel will give off a clear metallic ring. A cracked wheel will give off a dull sound with little or no ring

Portable Grinders

Portable grinders can be difficult to handle because of their size and weight. Some of the safeguards that apply to bench grinders--such as the ring test--also apply to portable grinders. In addition, operators should take the following precautions.

  • Use light pressure when starting to grind, especially with a cold wheel. Too much pressure may cause a cold wheel to crack and fly apart.
  • Hold the grinder firmly with both hands and grind with moderate pressure.

Let the grinder come to a complete stop before laying it down.

  • To avoid kickback, hold the grinder so that the rotating wheel pulls away from you.
  • Avoid sending sparks upward. Where practical, direct sparks sideways or downward.
  • Always unplug the tool before replacing or installing stones, disks, and cutters.
  • Use welding screens or other suitable barriers to contain sparks and grindings.
  • Let the grinder come to a complete stop before laying it down.
  • Handle portable grinders with care to prevent dropping. Inspect dropped grinders carefully for cracked or broken wheels.
  • Check the surrounding area for any people or property that might be hit by sparks. Make sure there are no flammables that could be ignited.