Like all power tools, portable grinders can present safety concerns, including flying particles and electrical hazards. This procedure outlines requirements in the Occupational Safety & Health Administration’s (OSHA) standards regarding abrasive wheels and tools (29 CFR 1926.303).
1. Preparation
- Remove flammable materials from the work area
- Ensure the work area is clean, free from slip, trip, and fall hazards, and well maintained
- Keep the power cord away from the grinding wheel and the material being ground
- Have personnel not involved in the immediate work step away a safe distance from the grinding area
- Secure work with clamps or a vice to free both hands to operate the tool
2. Inspection
- Unplug the power cord from the power supply before inspecting, adjusting, removing, or replacing parts
- Ensure the wheel guard is in place
- See OSHA Guard Removal Exception below. The guard must be approved for use by the manufacturer and cover 180° of the wheel.
- OSHA Guard Removal Exception only allows the guard to be removed for “internal grinding where the work acts as a guard”
- Check the abrasive wheel for cracks or flaws – replace if necessary
- Verify the RPM rating of the grinder does not exceed the RPM rating on the abrasive wheel
- When using a grinder that can switch between left-handed and right-handed operation, remember to move the wheel guard when you move the handle
- Tag out the grinder if a deficiency is found – do not use the grinder until the deficiency has been corrected
3. Ring Test
- Before installing an abrasive wheel, visually inspect it for cracks or flaws and perform a “Ring Test”
- Place your finger through the mounting hole of the new abrasive wheel
- Lightly tap its face with a hammer or metallic object
- A “ring” will sound from a good wheel
- A “dull thud” will sound from a wheel with an internal fracture.
4. Replacing the Wheel
- The abrasive wheel should not be forced onto a grinder, nor should the mounting hole size be changed
- To control the cracking of the abrasive wheel, it must fit freely on the spindle and be tightened to hold the wheel in place without distorting the flange
- The mounting nut should not be tightened excessively
- Run a newly mounted wheel at operating speed for 1 minute before grinding
- Always follow the manufacturer’s instructions.
5. Use all required Personal Protective Equipment (PPE)
- Wear appropriate PPE – safety glasses or goggles, appropriate face protection to protect against flying particles, and hearing protection to guard against hearing loss
- Gloves – Caution: Wear snug-fitting gloves to avoid snagging on the abrasive wheel or wire brush
- Apron, metatarsal safety boots, and respiratory protection may also be required depending on the work being performed
- Do not wear jewelry or other items that could become entangled in moving parts
- Avoid wearing loose clothing or secure loose clothing
- Tuck or secure long hair.
6. Switch Grinder “ON”
- Stand to one side and switch on the grinder
- Ensure the grinder operates smoothly and does not vibrate
- If you notice any unusual vibrations or noises, STOP
- Re-inspect the grinder and fix the problem immediately
7. Grinding
- Use both hands to maintain hold of the grinder
- Allow the grinder to reach full rpm before grinding
- Position yourself to avoid overbalancing
- When grinding, avoid placing excessive pressure on abrasive wheels
- Do not grind objects on the sides of grinding wheels
- Materials may become hot when grinding – use gloves when necessary
- Ensure the floor around the work area is clean
- Do not use wheels that are cracked or those that excessively vibrate
- Do not operate the grinder on wet floors.
8. Switch Grinder “OFF”
- Switch off the grinder when done
- Wait until the wheel has stopped turning before placing the grinder on the working surface
- Unplug the power cord from the power supply
- Clean the area and dispose of grinder particles
9. Other Precautions
- Do not use liquid coolants with grinders, as this may cause the metal to shatter
- Do not clamp portable grinders in a vise for grinding hand-held work
- Do not keep any materials close to the grinding wheel when it is not in use
- Do not carry a grinder by the power cord
- Do not pull on the power cord to disconnect it from the power supply
- Keep cords away from heat, oil, and sharp objects or edges
10. Maintenance & Storage
- Grinding wheels can become damaged and unusable before they are ever utilized. To avoid this, it is crucial to follow proper grinding wheel storage procedures. Appropriate abrasive wheel storage racks should be designed, constructed, and located to fit the needs of the user. The following factors should be considered:
- All abrasive wheels should be stored in a dry area (away from water and solvents) in rooms not subject to extreme temperature changes because some abrasive bonds may be affected by humidity, dampness, and temperature differentials. Racks should be located as near as practical to the grinding location but never where there is a danger of damage from passing trucks, crane handling, or excessive vibration.
- The racks, bins, and drawers should be constructed so that each of the various types of wheels can be stored in an orderly and safe manner. Wheel selection should be possible with minimal handling, and it is recommended to store wheels so that the oldest wheels in stock are used first. The selection of racks, bins, boxes, or drawers for storage depends on the size and type of wheels. Note that blotters supplied loose should be stored flat.
- When needing to place the machine down to do other tasks, a wheel/ machine storage rack or other protective means should be used. The operator should never toss the machine or allow the wheel/machine to drop onto the floor because these actions could damage the wheel and lead to breakage. Additionally, if the wheel is placed in a vulnerable spot, the operator may not be aware of the damage that could have resulted while he or she was away.
