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Right resources + enough time = safe finishing

Safe grinding and polishing require both the right resources and sufficient time

Yesterday a job arrived late at your co-worker’s grinding workstation, so he rushed through it as fast as he could. He pushed hard to grind down the welds as fast as possible. Pushing harder seemed to make a difference; he was working harder, so he must be grinding faster, right? This morning, though, someone from the paint line saw some unacceptable burrs, and so he took a small batch of parts back to the finishing department for rework.

The finisher’s work gloves and safety glasses are across the room—no time for those, so he grabs the parts and holds them down on the worktable. Why bother clamping them in a vise? After all, it’s just a quick touchup, right? He grabs the grinder with his other hand and then, well, this story doesn’t have a happy ending.

This narrative has so many problems, and it illustrates how without the right tools, personal protective equipment (PPE), and company procedures, grinding and polishing can be one of the most dangerous jobs in the fab shop.

Finishing is called finishing for a reason. The finishing aspects, including grinding and polishing, usually are the last to occur before a job moves on to paint, assembly, or packaging. By the time grinding and polishing are ready to begin, the project may be behind schedule or need to be completed in less time than anticipated. But rushing these important steps not only can result in a less-than-desirable finish to your parts, but also an unsafe workplace.

If you read safety literature on grinding and polishing, you know that much of it sounds utterly obvious, and you might think that anyone with a little common sense would follow the rules. But when workers are in a rush—and, indeed, are judged and sometimes paid by how quickly they can complete their work—common sense sometimes takes a back seat.

If managers or customers pressure you to just get the job done as fast as possible, don’t push forward too quickly at the risk to both job quality and your personal safety. If the project is taking longer than anticipated, managers need to reassess the time needed to complete it. To ensure you can execute the project with attention to both detail and safety, they should review what is needed and communicate that information with all stakeholders, including everyone in the grinding and finishing department, managers, and customers.

Once managers ensure your finishing team has the time it needs to perform quality work, they then can focus on the resources the grinding and polishing department needs to ensure everybody can perform the work safely and efficiently. These include five key areas: working environment, personal protection, fixturing and ergonomics, tools and abrasives, and power sources.

Environment

Ensuring safe working conditions starts with a safe working environment. Operating a hand-held tool that can turn a cutting disc at upwards of 10,000 RPM is the equivalent of having a deadly weapon in your hands. You always should be aware of any potential hazards nearby.

To protect both yourself and others in the area when grinding, keep the workspace as clean and neat as possible, with minimal clutter and free of tripping hazards, such as extension cords, pneumatic hoses, and any unnecessary items on the floor. When you have to move around the workpiece, you should be confident that nothing will hinder your movement or cause you to stumble, fall, or drop the tool.

Because grinding can produce sparks, keep flammable materials such as rags away from the workpiece. Dealing with a small, unexpected—yet completely avoidable—fire will definitely put the job behind schedule.

Figure 1
Grinding throws hot sparks and workpiece debris, so personal protective equipment is a must. Courtesy of Getty Images.

Personal Protection

When grinding, you wield a tool with a high-RPM abrasive wheel that throws sparks and workpiece debris. If that debris flies onto your skin or eyes, it can cause serious injury. You also don’t want this debris embedded in the clothes you wear home, so minimize the amount of skin you leave exposed. Personal protective equipment (PPE) from head to toe is a must (see Figure 1).

Wear either a shop coat or protective coverall as well as full wraparound eye protection. Also wear high-quality work gloves as well as work shoes that are both protective and comfortable, suitable for long periods of standing. Avoid loose clothing, such as pants with cargo pockets. It’s also highly recommended that you wear a facemask to protect against any fine particles that may be generated during grinding.

When grinding or finishing stainless steel, wear extra respiratory protection to protect yourself from hexavalent chromium, a toxic form of the element chromium. Consult the OSHA guidelines for working with stainless steel, as hexavalent chromium has been linked to irritation of the nose, throat, lungs, eyes, and skin. It has also caused lung cancer in workers who breathe the airborne particles.

Common sense is key. Keep all long hair, whether on the face or head, contained with a hat or other hair-restraint device. Wear appropriate ear protection, but never listen to music through earbuds or headphones while grinding. Your ears need protection, but you also need to hear enough so you know what’s going on around you. Also, limit your cellphone use to break time, away from the work area.

And, of course, avoid any chemical that may affect concentration, including any illegal drugs and marijuana. You should also be cognizant of the ingestion of legal substances, such as caffeine, nicotine, and prescription drugs, and the effects they may have on performance.

Fixturing and Ergonomics

You may wear all the right PPE and yet after a week of grinding still become injured. Safety in finishing isn’t just about what you wear; it’s also about how you work. You need to fixture the workpiece securely and position it for easy access.

Hold and maneuver the grinder with both hands. Never grind a workpiece while holding it in your hand. Instead use a reliable workholding device like a vise. Ideally, you should hold the grinder somewhere between waist and chest height, and have your arms at a comfortable 45-degree angle. Safe grinding cannot occur if you hold the tool overhead, bent over at the waist, or in any other position that compromises your ability to securely hold the grinder.

If your grinder has a top handle, be sure your thumb is under the handle. This gives you a more secure grip and more control over the tool, which you’ll need if you experience any resistance while grinding.

Resistance includes rotational kickback, which happens when the abrasive catches on an edge or large burr on the workpiece. The wheel stops rotating, but its rotational energy has to go somewhere, so it transfers back to you. Violent kickbacks can severely cut your hands, arms, head, torso, and legs. And if you’re not holding the tool securely, you can lose control and injure others around you.

To avoid this, turn on the grinder and allow it to increase to operating speed before contacting the workpiece. When grinding, let the tool and the abrasive do the work. By applying the minimum pressure needed, you will achieve the desired result and lessen the possibility of rotational kickback.

Figure 2
If you can’t access a workpiece without removing a guard, you have the wrong tool for the job. Here, the operator accesses the work area with a finger belt sander.

Tools, Abrasives, and Accessories

Say you fixture and position a workpiece as best you can, try to apply minimal pressure to avoid kickback, but still can’t get the job done without contorting yourself or having your tool kick back at you. That’s because you’re missing one critical element of safety. You need to have the right tool and accessories for the job, and you effectively can boil it all down to this: Correct tool + Correct consumable + Application + Environment = Safety, productivity, and profit.

Always operate the grinder within the specifications designated by the tool manufacturer. All guards and safety devices that came with the tool should remain on the tool. If you can’t access a workpiece without removing a guard, you have the wrong tool for the job (see Figure 2).

All handles and guards should be inspected regularly to make sure they are securely attached and in working order. Any abrasives, guards, and accessories attached to the tool must meet ANSI B7.1 standards.

Using hard, resin-bonded grinding wheels, a right-angle grinder operates at high running speeds to allow the contact between the workpiece and the wheel to fracture the abrasive’s grit during grinding and expose new grinding grains. This process continues to renew the surface of the grinding disc so it performs at maximum efficiency during its operational life.

The wheel’s diameter and function determine its maximum RPM, and if you operate the grinder at a faster RPM, the tool will at best not perform as expected and potentially damage the workpiece. At worst, the abrasive disc will explode and injure anyone in the vicinity.

When attaching or changing over an abrasive wheel, unplug and place the tool on a stable, level surface. Inspect the new abrasive to make sure it is not defective or damaged, and attach it to the tool with the correct flange and locking nut. If you or anyone else drops the abrasive, inspect it thoroughly for cracks and damage. When in doubt, throw it out. Any compromise to the consumable’s structural integrity could result in disc breakage or explosion.

After turning off a grinder, wait until the disc stops rotating before setting the tool down. When the tool is not in use, disconnect the power and gently set it down on a level surface with the abrasive facing upward.

Power Source

Most angle grinders are powered by electricity. When possible, plug power cords directly into the electric receptacle to ensure the tool receives the proper amperage. If the application requires extension cords, be sure that the cords are rated to support the power that the tool requires. Poor-quality cords can reduce power and cause inefficient operation or premature tool failure. Inferior cords also can overheat and become a fire hazard. And, of course, never operate electric-powered grinders in or around water, such as near puddles or in inclement weather.

Pneumatic angle grinders present their own set of safety considerations. Air tools are designed to run on a predetermined air volume and at a certain pressure, sometimes specified as CFM@PSI. If there is too little CFM@PSI, the tool won’t work. If there is too much, the tool can run too fast and possibly override the maximum RPM rating for the abrasive. It can also compromise tool seals and cause internal damage. Air tools tend to have a higher RPM than electric tools, so pay close attention to the ratings given by the tool and abrasive manufacturer.

It is highly recommended that you use the air tool as close as possible to the source of air. Longer lines with multiple connections can lose air pressure and give you less-than-desirable tool efficiency. Furthermore, the air used to power a tool is heated in a compressor. The farther away you get from the compressor, the more the air cools in the lines, setting the stage for moisture to enter the tool and cause internal damage to its components. When working in colder temperatures, moisture and even ice are distinct possibilities.

To mitigate this issue, use an air separator and lubricator in the air system as close as possible to the tool. This, in combination with a high-quality air tool lubricant in the grinder itself, is a must to ensure maximum operator safety and optimal tool performance.

Establish a Safety Routine

So many safety rules follow common sense: Wear appropriate PPE. Fixture the workpiece properly. Still, obvious rules aren’t so obvious when a rush job arrives in the finishing department.

Establish a consistent safety routine. This will help eliminate some of the time and expense variables when the project comes to its final stages. Most important, it will benefit all parties involved, including you, the fabrication company, and the customer.

What’s unsafe here?

Just about everything

Thank goodness this photo is staged. The area is a mess.

Flammable fluids and electrical cabinets are nearby. The operator is listening to music through headphones, oblivious to his surroundings, including a nearby coworker. He’s holding the workpiece with one hand and the grinder with the other. There’s no personal protective equipment (PPE) to be seen. And all this doesn’t even consider the tool he’s using or the abrasive. To ensure your operation never comes close to this staged photo, refer to the following checklist:

Workspace

Neat clutter-free workbench

No trip hazards (extension cords, air lines, etc.)

No flammable materials

Personal Protection Equipment (PPE)

Shop coat or protective coverall

Full, wraparound eye protection

High-quality work gloves

Comfortable, protective footwear

Face mask or respiratory protection

Ear protection

Fixturing/Ergonomics

Workpiece is secured in vise

Grinder is held securely with both hands

Grinder is operated at waist/chest height

Arms are at comfortable 45-degree angle

Grinder is at operating speed before contacting workpiece

Tool/Accessories

All required guards, handles, and safety devices are attached to tool

All abrasives, guards, and accessories meet ANSI B7.1 standard

Abrasives are rated for tool RPM

Replacement abrasives are in ideal condition and secured with correct hardware

Grinders not in use are disconnected from power and placed on stable surface

Power Source

Electric:

Power cords are plugged directly into receptacle

Extension cords, if used, are rated for tool’s amperage

Operation does not occur in or near water or in inclement weather

Pneumatic:

CFM@PSI of tool matches output of air source

Max. RPM of air grinder corresponds with max. RPM of abrasive

Tool is operated as close as possible to air source

Air separator and lubricator are used when available

High-quality air-tool lubricant is used in grinder

Correct tool + Correct consumable + Application + Environment = Safety, productivity, and profit