Because safety tips and best practices can vary by tool (die grinder, right-angle grinder, or bench grinder) and by product type (bonded abrasives, coated abrasives, and power wire brushes), it’s important to know what the safe operational practices are for each tool and product type.
It’s human nature to do whatever it takes to get the job done. When a product or tool isn’t performing as expected, it’s natural to want to take it upon yourself to adjust form or technique to make the product do the job. But when pushed beyond the conditions of their design, these products can pose danger to you, your co-workers, and the equipment around you.
Reducing the potential for personal injury is always the most important goal. Preventing injuries also saves operations time and money, and using wire brushes and abrasives properly can result in performance and efficiency benefits that impact the bottom line.
For safety purposes, you should always match the speed rating and size of the wire brush or abrasive product to the tool. Just because a product fits on a tool doesn’t mean it can be used on that tool safely.
Any tool or product designed for cutting, grinding, or finishing is marked with a maximum RPM rating. For example, a 41⁄2-in. right-angle grinder is typically rated at 11,000 RPM, while a 41⁄2-in. cutting and grinding wheel is typically rated at about 13,000 RPM. The product’s RPM rating should always be equal to or greater than the RPM rating of the tool it’s being used on.
Another common mistake is using a brush, disc, or wheel that is the wrong size for the tool. One example is putting a 6-in. wheel on a 41⁄2-in. grinder. Some may think the larger wheel or disc will provide a deeper cut or longer life, or perhaps it’s the only product on hand. But when accessories don’t fit the tool, they can run out of balance and vibrate excessively, causing loss of control or accessory failure.
As a safety best practice, always keep the guard in place while operating the tool. This prevents using the wrong size accessory on the tool.
Applying the appropriate pressure and letting the tool do the work plays a huge role in achieving optimal performance.Abrasive grains dull over time. If you feel the tool isn’t performing as it should, you may respond by applying more pressure. This is counterproductive to product performance and life, as well as safety. Adding extra pressure actually dulls the grains even more, reducing their ability to cut. It also generates heat, which ultimately causes the product to break down more quickly.
With wire brushes, applying too much pressure puts stress on the wires and causes the filaments to break, which is a safety hazard that also shortens product life. Light pressure that allows the wire tips to do the work is best when using wire brushes.
One telltale sign that indicates you are using too much pressure is an audible drop in RPM. If you can hear the RPM of the tool drop or hear and feel the motor straining and bogging down, you are likely applying excessive pressure.
The rate of movement across the work surface can also have an impact on performance. This is especially true when using ceramic grains. Fast, choppy strokes typically produce less-than-optimal results, while longer, slower strokes allow the grains to do the work.
Changing the position and angle of the tool in relation to the workpiece can greatly affect product performance, efficiency, and life.
When using a Type 27 (flat) profile flap disc, for example, use lower grinding angles (5 to 15 degrees) and lighter pressures. When grinding with a Type 29 flap disc for stock removal and aggression, work at an angle of 15 to 35 degrees. Compare that to a cutting wheel or wire wheel, which you should use at a 90-degree angle perpendicular to the part. Varying the position by even a few degrees can put significantly more stress on the wire or abrasive, reducing performance and possibly causing product failure.
Generally speaking, the lower the angle, the slower the cutting but the longer the product life. Conversely, the steeper the grinding angle, the faster the product cuts and wears.
Products are available in varying profiles, which can be helpful for specific applications such as reaching into a tight space or corner.
It’s also important to monitor how long you have used the product and to watch for any signs of damage or wear that could pose a safety risk.
Cutting wheels and wire brushes wear down over time, becoming increasingly smaller in diameter. As this happens, you may need to adjust your angle of approach, orientation to the workpiece, and the pressure you apply to compensate for the loss of diameter while maintaining effective cleaning or grinding.
Before using any product, inspect it for rust, corrosion, missing flaps, uneven edge wear, cracks, or chips. Never mount a damaged product, and always inspect it for signs that it has been dropped or damaged. If the product has been dropped—or you suspect it has been dropped—be aware that there could be cracks or chips that aren’t visible.
Time also refers to how long you dwell in one spot on the workpiece. It is important that you minimize that time. Dwelling builds friction and heat, which contribute to the product breaking down faster, which can overheat or damage the workpiece. Be sure to keep the product moving with consistent, controlled strokes.
To help optimize performance and extend product life, always store wire brushes and abrasives in a clean and dry location.
Keep in mind, however, that even when products are stored in an appropriate dry location—such as a toolshed—they can still be exposed to significant or extreme changes in temperature and humidity. If this is the case, allow the product to return to ambient temperature before using it for cutting, grinding, or finishing. When a grinding wheel is extremely cold, it can become brittle, and grinding with it immediately can cause wear or failure faster than normal.