Guarding of Portable Abrasive Grinding Wheels

Date First Published on SafetySmart Compliance: January 11th, 2012
Topics: Power Tools |

Safety requirements for portable abrasive wheels, i.e., mounted wheels used in grinding operations that can be moved around are contained in 1910.243(c) (but don’t apply to natural sandstone wheels or metal, wooden, cloth or paper discs that have a layer of abrasive on the surface).

Safety Guards Required

A safety guard is an enclosure designed to restrain the pieces of the grinding wheel and provide protection in case the wheel breaks during operation. Safety guards must cover the spindle end, nut and flange projections, be mounted so as to maintain proper alignment with the wheel and the strength of the fastenings must exceed the strength of the guard.

Safety guards used on machines known as right angle head or vertical portable grinders must have a maximum exposure angle of 180 deg, have the guard located between the operator and the wheel during use and allow for adjustment of the guard in a way to ensure pieces of an accidentally broken wheel will be deflected away from the operator if the wheel breaks.

The maximum angular exposure of the grinding wheel periphery and sides for safety guards used on other portable grinding machines must not exceed 180 deg. and the top half of the wheel must be enclosed at all times.

Mounting of Abrasive Wheels

Wheels must be closely inspected and sounded by the user immediately before mounting to ensure that:

  • They haven’t been damaged in transit, storage or otherwise;
  • The spindle speed of the machine isn’t over the maximum operating speed marked on the wheel;
  • The grinding wheel fits freely on the spindle and remains free under all grinding conditions;
  • There’s a controlled clearance between the wheel hole and machine spindle (or wheel sleeves or adaptors) to avoid excessive pressure from mounting and spindle expansion;
  • All contact surfaces of wheels, blotters and flanges are flat and free of foreign matter; and
  • Bushing used in the wheel hole aren’t wider than the wheel and don’t contact the flanges.



Keep in mind that these rules apply to portable abrasive wheels. Fixed abrasive wheels must be guarded according to the machine guarding standard set out in 1910.215.