Finishing the Job

Four key factors to keep in mind when operating tools such as right-angle grinders, flap discs, die grinders, and cutoff wheels are speed and size, pressure, orientation, and time.

Each operator of a power tool plays a role in making sure safe practices are always being followed. Paying attention to four key factors— speed and size, pressure, orientation, and time—when using hand-held power tools and accessories for surface conditioning and cleaning can help operators improve safety and efficiency and extend product life, resulting in time and money saved for the operation.

Practicing basic safety rules when using hand-held power tools and accessories not only contributes to safer conditions for the machine or tool operator, it can also contribute to cost savings for the shop through improved productivity and extended consumable life.

Among the key issues operators should keep in mind when operating tools such as right-angle grinders, flap discs, die grinders, and cutoff wheels are speed and size, pressure, orientation, and time. All are directly under the operator’s control.

Factor No. 1: Speed and Size

It’s important to properly match the speed and size of the accessory with the speed and size of the tool. This is critical because the accessory, such as a brush or abrasive, should not be larger than any of the guards that are placed on the tool. A mismatch between speed and size of the accessory and the tool might make it more likely for the operator to remove the guard from the tool, which can jeopardize safety.

In addition, some accessories will fit on the tool with the guard in place, but the speed ratings of the tool and the accessory aren’t compatible. Just because an accessory fits on a specific tool does not mean it can be used safely on that tool. The RPM rating of the accessory should meet or exceed the recommended RPM rating of the tool for safest use.

Failure to properly match the RPM rating of the accessory and the tool can result in injury or poor performance. A tool turning at a higher RPM than the accessory can result in accessory failure and potential injury to the operator.

Also, an accessory that runs at a very low RPM might cause the operator to push harder on the tool to get the job done. This can lead to premature tool wear or breakage, inefficiency, and potential injury.

If the tool or accessory does not have an RPM rating stamped on it —for example, if the rating wears off or it’s unreadable—the operator should not use it. Without knowing the RPM rating, an operator cannot ensure that an accessory is satisfactorily rated for the speed of the tool.

Overspeeding or underspeeding the tool are other issues to be aware of that can cause potential safety problems.

Factor No. 2: Pressure

Monitoring pressure is another important factor under the operator’s control when using hand-held power tools and accessories. Using the appropriate pressure for the tool helps contribute to safe usage.

Using an accessory for too long can lead to safety issues for the operator, as well as product inefficiency.

If the operator must push harder to get the job done, it adds to the potential for injury, and it can also lead to greater operator fatigue. With any hand-held tool, the more pressure the operator applies, the greater the chance for slipping or injury.

In addition to potential safety hazards, using too much pressure with hand-held tools can also greatly reduce the life of the product, which is costly and inefficient. When an operator puts excessive pressure on a wire brush, for example, the force on the wire tips and filaments can lead to long wire breakage. This poses a safety risk and reduces product life.

It can be difficult for an operator to gauge the appropriate amount of pressure to apply with a hand-held tool. In many cases, the weight of the tool alone should be sufficient pressure if the proper accessory is operated at the appropriate speed.

Factor No. 3: Orientation

Every tool and accessory needs to be used at the proper angle to the workpiece for maximum safety. The proper orientation often depends on the tool or accessory being used, so it’s important for operators to keep in mind that different tools may require different orientations to the workpiece.

A grinding wheel and a wire wheel should not be used at the same angle to the workpiece, for example, because they are not designed to be used in the same manner.

A wire brush is designed so that the wire tips do the work in striking the base material, so it should be held at an angle that uses only the wire tips. Holding it at an incorrect angle uses the sides of the wires instead of the tips. This doesn’t provide a good cleaning action, making it inefficient and reducing productivity.

The same holds true for flap discs. If the operator does not orient the tool properly, he will not use the entire work surface of the flap, a practice that is inefficient and can lead to premature wear of the product and too many changeouts of the accessory. Most flap discs work best at an angle between 15 and 30 degrees.

If the angle of the tool is too great, the operator is not using the work surface of the tool as it was designed, so he is not removing as much material as he could and is wasting a good portion of the disc.

If the work angle is too low, there is the potential for kickback, which makes it harder for the operator to control the tool and poses a safety hazard.

Factor No. 4: Time

Operators of course want to maximize product life to get the most out of the product investment and save time, but using an accessory for too long can lead to safety risks for the operator, as well as product inefficiency.

For example, the diameter of a grinding wheel gets smaller and smaller with natural wear as it is used. As it gets smaller, the wheel becomes harder to control. Operators must be aware that the wheel should be changed out when wear becomes apparent to help optimize safe and efficient use of the tool.

Another example is long wire breakage with a wire brush. This indicates a much quicker breakdown of the remaining wires, so long wire breakage is a sign to stop using that brush.

It’s important for operators to recognize the signs of wear for each accessory or tool and to know when it’s time to replace it. Using a tool or accessory beyond its useful life can lead to safety hazards and greatly diminish its effectiveness.

Some manufacturers offer technologies that can help extend product life. One example is a brush technology that makes flipping the accessory easier and maximizes wire life and safety as a wire brush wears. It has a hex nut on each side of the wheel that allows the operator to remove the brush easily from a right-angle grinder and flip it. This allows him to use the other side of the wire tips, which become razor-sharp as the opposite side wears.

The hex nut design has a profile that provides adequate tool clearance, so there is no need to remove the guard from the grinder to change the position of the wheel.

Tips to Keep in Mind

Beyond these four key factors are some other items to remember when using power tools and accessories. These tips can help improve safety no matter the application or work environment:

• Follow the manufacturers’ safety instructions for all tools and accessories. Read the manual or instructions prior to doing anything with the tool.
• Inspect the tool or accessory each time it is used to check for signs of wear or damage.
• Take advantage of educational safety training offered by some manufacturers, which is designed to help ensure proper and safe use of tools, accessories, and consumables.
• Consider the ROI when purchasing tools and accessories. A highquality, heavy-duty power tool typically has a longer life span for greater efficiency and reduced downtime for changeover, which can offer a faster payback.

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