Auto Service World
Feature   May 1, 2001   by CARS Magazine

Grinders: a common injury source

Machine-related injuries are one of the leading types of lost time injury in Ontario, according to The Workplace Safety and Insurance Board, with 7623 claims in 1999.Pedestal or bench grinders are per...


Machine-related injuries are one of the leading types of lost time injury in Ontario, according to The Workplace Safety and Insurance Board, with 7623 claims in 1999.

Pedestal or bench grinders are perhaps the most common form of workplace machine in Canadian shops, and account for a considerable percentage of those injuries. Grinders seem innocuous, but the combination of abrasion, heat and high rotational speeds that can send debris flying make the simple machines an underrated hazard. Some grinder injuries are serious, so a few basic safety guidelines make sense around these machines:

1. Overall machine condition

What is the overall condition of the machine? Is it securely mounted on a bench or pedestal? Is the power cord secured out of the way and is it in good condition? Is the strain relief bushing (where the cord enters the machine) intact, and is the grinder adequately grounded? Is the grinder fused, or powered by a protected circuit? Does the grinder run without excessive vibration, and are the tool rests intact and properly adjusted? Are all shaft nuts intact, not rounded, and are the correct washers and spacers installed?

2. Guard considerations

Are guards and side plates installed and adjusted properly? Are clear components crack-free and free of fogging or haze? Are grinder-mounted spotlights working, and adjusted top illuminate without blocking the operator’s view of the work piece?

3. Working area issues

Is the working area around the grinder clear? Is there enough room for other personnel to pass behind a grinder operator with good clearance? Is the floor around the grinder clear and free of oils or other slip hazards? Is there adequate ambient light to augment task lighting? Is a quench bucket near enough to the machine to allow quenching within the operator’s field of view? Are flammable materials in close proximity to the grinder?

4. Grinding wheels

Is the correct wheel available for the job? Is a dresser readily available? Has the installed wheel been “ring tested” before installation? (see below) If a wheel fractures, are people or other dangerous objects in the path of the flying debris?

5. Personal safety

Have inexperienced operators been shown safe grinder practices? Do technicians use safety shields and approved footwear? Is long hair tied back, and loose clothing and jewelry removed? Does the operator know how to safely test and install grinding wheels, and adjust guards and tool rests? Does the technician know the location of eye wash stations and first aid kits?

Testing Grinding Wheels

Grinding wheels should be inspected at every change, whether new or old. Obvious cracks or serious voids make a wheel unsafe in all cases, but some flaws are less apparent. The “ring test” helps find hidden flaws and only takes seconds to perform: suspend the new wheel from it’s spindle hole by a screwdriver, and gently tap the sides of the wheel in four equally spaced places with a plastic or wooden handled screwdriver. The wheel should “ring”; if the sound is a dull “thump” and is inconsistent at the four tapping points, set it aside for closer inspection.


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