We get asked a lot about grinder guarding because there seems to be confusion about the safety requirements. Indeed, the common bench & pedestal grinder is found in almost every machine shop and is undeniably a workhorse. In fact, due to the popularity of these machines, they are often cited by OSHA for safety violations. There are various grinders, such as surface grinders and angle grinders, but we will focus on the common bench grinder for this article.
Grinder Guarding Regulations
Both OSHA and ANSI have standards and regulations that concern grinder guarding. OSHA 29 CFR 1910.215 – Abrasive wheel machinery, and ANSI B11.9-2010 – Safety Requirements for Grinding Machines have machine guarding regulations for bench grinders and other machines such as surface grinders. Another applicable ANSI standard is ANSI B7.1 which deals with the safety requirements for the use, care & protection of abrasive wheels.
What is a Bench Grinder?
A bench grinder is a machine with two abrasive wheels attached to either side of an electric motor, which spins them. An operator uses these rotating abrasive wheels to sharpen tools and grind material.
Grinder Safety Guarding
1. Grinder Guarding
The portion of the grinding wheel that is not being used must be guarded, including the sides and an opening of no more than 65 degrees to allow workers access. If the grinding wheel shatters or explodes, the guarding will minimize the risk to the operator and bystanders. Never use the grinder with any covers or guards removed.
Make sure your bench grinder has a horizontal work rest to prevent entanglements. Adjust the work rest to 1/8-inch of the grinding wheel to avoid creating a nip point. Workers must readjust the work rest as the grinding wheel gets smaller due to usage.
3. Tongue Guard / Spark Arrestor
The tongue guard is a simple metal plate adjacent to the work rest that minimizes flying sparks and wheel fragment ejections toward the operator. The distance between the tongue guard and grinder wheel must never exceed ¼-inch. As with the work rest, the tongue guard must also be adjusted as the wheel wears down due to use.
4. Eye Shield
The eye shield on a grinder minimizes projections from grinding material. Depending on the material, hot spark projections towards the body and face of an operator can be substantial.
OSHA 29 CFR 1910.215 does not mention having eye shields on bench grinders. However, OSHA 1926.303(c)(9) does mention, “All employees using abrasive wheels shall be protected by eye protection equipment.” We always recommend wearing safety glasses and a face shield. But of course, there will be cases when someone uses a grinder without any safety glasses or face shields, so we always stress that it is important to have transparent bench grinder-mounted shields in place.
In truth, the small shields included on the grinders are small and flimsy. This is where a properly designed and large shield makes all the difference. For example, Ferndale Safety’s bench grinder shield features over 58 sq. inches of protection, or their laminated safety glass model, which resists burning from hot sparks. These shields are a worthwhile investment and add to your sense of security while using the machine.
Grinder Guarding Safety Tips
- Always make sure all guarding is in place and replace any damaged guarding.
- Ensure you adjust the work rest to 1/8” of the grinding wheel.
- Ensure you adjust the tongue guard to ¼” from the grinding wheel.
- Position the eye shield between your line of sight and the point of operation.
- When starting a grinder, please wait until it reaches full speed before usage.
- Do not grind on the side of the wheel. Doing this may cause the wheel to shatter.
- Do not allow your workpiece to get too hot by excessively or aggressively removing material.
- Cool your workpiece by placing it in a cooling fluid such as water.
- Do not force the material into the wheel – let the grinding wheel do the work for you.
- Properly fasten the grinder to a workbench or pedestal.
- Never grind aluminum or magnesium.
- Do not grind material that is too small to hold.
- Inspect the grinding wheel for any chips or cracks and replace them if any appear.
- Never wear loose-fitting clothing or ties, and tie your hair back if it is long.
I always recommend adding anti-restart protection to any machinery, including bench grinders. These devices prevent a machine from restarting by itself after a power outage. A simple anti-restart device has buttons to start and stop the machine instead of switches. We recommend getting an electronic brake that stops the spindle in seconds instead of minutes for large grinders with massive wheels.