How to Use Your Grinder Safely and Soundly

BY DEBRA J. WILLIAMS, the senior product safety engineer at Norton | Saint-Gobain Abrasives, Worcester, Mass.

Reprinted with permission: The AWS Welding Journal

Follow these guidelines to protect yourself and others during grinding applications

The advantages of using grinding wheels are widely known for weld preparation, cut-off, and finishing applications. When used safely and properly, grinding wheels will serve you well. However, when grinding wheels that spin at thousands of revolutions per minute (RPM) are damaged or misused, they can break into bullet-like fragments, leading to injury.

Grinding safety is a vast subject, with seemingly limitless tips, but the following offers just a few key guidelines to keep top of mind.

Use the Right Machine Guard

Wheel guards help protect the user from sparks and debris during grinding as well as from broken fragments if the grinding wheel fails. Protective guards are crucial in keeping grinding wheel mishaps from leading to personal injury — Fig. 1. As a result, guards are required by the Occupational Safety and Health Administration (OSHA) and should always be used.

However, hazardous conditions can also be created by the ineffective use of guards. Using a damaged wheel guard poses a risk to the safety of the operator and bystanders. Guards that are cracked, deformed, bent, or severely worn must be replaced. Once a guard has been damaged, it may become ineffective in catching broken fragments if the grinding wheel breaks. If wheel breakage occurs, the guard must be inspected, and if there is any sign of damage, the guard must be replaced.

 Machines with missing wheel guard fasteners also pose a safety risk. Sometimes during routine machine maintenance, the guard fasteners are damaged and not replaced when the machine is reassembled. During a wheel breakage, the missing fasteners may allow the guard to move, become unattached from the machine, or open. This improperly attached guard may become a new hazard, exposing the operator to injury by the guard or not containing the wheel fragments in the event of a wheel break.

The operator should always use the guard that is recommended for the machine and its operation. A guard made of tin, cloth, wood, or other materials not designed to contain wheel fragments may fail when struck by a wheel fragment. The operator should never paint or otherwise disguise the wrong material for a proper guard.

Altered or cut back guards are considered hazardous. For example, reducing the size of Type 27 and 28 guards, which are designed to cover the wheel and plane of rotation between the machine and operator for at least 180 deg, to 90-deg coverage of the wheel poses a risk to the operator that is nearly as bad as having no guard in place.

Guard Scenarios to Avoid

• Incorrect Scenario #1. The following scenario should be avoided: Using a Type 6 or 11 cup wheel on a portable angle grinder with a Type 27 or 28 raised hub or depressed center grinding wheel guard.

Explanation/Tips for Scenario #1. While a properly adjusted Type 27 or 28 guard works with a Type 27 or 28 wheel, it offers little or no protection with a Type 6 or 11 cup wheel. The cup wheel hangs below the guard meant for a Type 27 or 28 wheel and, in the event of a wheel breakage, offers little or no protection.

• Incorrect Scenario #2. The following scenario should be avoided: Using a Type 41 straight cut-off wheel on a portable angle grinder with a Type 27 or 28 raised hub or depressed center grinding wheel guard.

Explanation/Tips for Scenario #2. Type 27 and 28 guards are open on the bottom to allow for side grinding with a raised hub or depressed center wheels. When side grinding with a Type 27 or 28 wheel, the workpiece acts as protection for the guard, safeguarding the operator in the event of wheel breakage. Cut-off wheels are not designed for use on their side and must be used on their outer periphery only. Guards for cut-off wheels must cover a full 180-deg area on all sides of the wheel. When using a cut-off wheel with a Type 27 or 28 guard, there is no guard on one side of the wheel to protect the operator in the event of a wheel breakage. Do not use cut-off wheels on angle grinders without the proper guard.

Even worse, the operator may be tempted to remove the guards entirely. The most ineffective guard is the one that has been removed from its machine and is sitting in storage. The removal of a wheel guard on a machine in operation is not only dangerous, it is also illegal.

Utilize Personal Protective Equipment (PPE)

 In addition to following best practices for grinding tools, it is vital to protect the body using the approved PPE.

To protect against airborne sparks and metal chips, a face shield should be worn along with safety glasses that have a strap to prevent slippage. The operator should ensure that both the safety glasses and the face shield fit well and won’t fall off or move around during grinding applications.

 Wearing flame-resistant clothing and gloves to protect against burns and cuts is equally important. Gloves also absorb some of the vibration during grinding, which helps minimize operator fatigue.

Other PPE that should be worn includes ear and respiratory protection. Wearing ear plugs or muffs is beneficial in preventing hearing loss caused by noisy grinding operations. To protect lungs, at minimum, a dust mask should be worn, and some jobs will require that a respirator be used for even greater protection. Safety data sheets for both the material and abrasive wheel being used should be reviewed to determine the optimal respiratory PPE.

Choose the Correct Wheel for the Job

The correct pairing of a grinding wheel to the grinder is critical for safety as well as the success of the application. Every time a wheel is mounted or remounted onto a machine, the operator must check the wheel and machine’s speed to make sure the wheel is not operated in an over-speed condition. The abrasive wheel’s safe operating speed is marked on the wheel, and the machine’s normal operating speed is marked on the machine. The operator should never exceed the wheel’s safe operating speed as stated in RPM or in surface ft/min. Failure to comply with this requirement is not only dangerous, it is also a violation of American National Standards Institute (ANSI) safety requirements and OSHA law. It is recommended to operate the machine at or below the wheel’s maximum rate speed.

Additionally, bigger is not better when it comes to the wheel as compared with the grinder. Follow the recommendations on wheel size supplied with the grinder, and be sure the wheel properly fits within the wheel guard.

Follow Proper Storage Procedures

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 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.

• Copies of all safety folders and notices should be prominently displayed in the storage area.

• After usage, proper storage of abrasive wheels is also important. Abrasive wheels must be removed from the grinder during overnight storage and while moving the machine from one location to another.

• 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 damage that could have resulted while he or she was away.

Establish an Inspection and Maintenance Program

Maintenance of grinding tools and abrasives are paramount to productivity and safety. A good start and end to the day should include inspection of the tools being used.  All wheels should be inspected for breakage, nicks, or cracks. Even wheels that have been in storage might have been compromised if the proper conditions were not in place. After inspecting the wheel and determining its integrity, the wheel should be run at operating speed for at least 60 s in an enclosure (e.g., metal barrel, etc.) prior to grinding. It is also important to know that the inspection and testing of a grinding wheel is not a one-and-done task. For each new grinding process, the procedures should be repeated.

 No matter the power type, cords and hoses should be inspected to ensure no damage has taken place since last use. The operator should also check for correct power source connections and settings. Proper, undamaged guards and flanges should always be attached. Any questionable parts should be repaired or replaced to ensure the safety of all personnel.

In addition to inspection, an effective maintenance program includes proper storage after initial use. It is common to see abrasives scattered across workshop tables, welding truck beds, and tool boxes. It’s a good habit to remove abrasives from the tool after use and dispose of anything damaged. Leaving them attached allows someone to pick up the tool and use it with the possibility of something getting damaged without it being known to the next operator. Keeping unused abrasives in their proper storage box and designated location offers quick abrasives identification and helps prevent edges from being chipped or dinged.

Furthermore, it is recommended to use the original box for storage because it provides information for proper abrasives selection and safety protocols. It also allows for inspection before mounting, an excellent preventive maintenance measure.

Conclusion

There are many guidelines for grinding safety, but following the simple recommendations listed in this article can help you avoid some of the most common hazards associated with grinding. For additional information on grinding wheel safety, please refer to ANSI B7.1, Safety Requirements for the Use, Care and Protection of Abrasive Wheels.

Fig 1. When used correctly, grinding wheels can help you achieve weld preparation, cut-off, and surface finishing safely and effectively.