Abrasive Wheel Grinders – What You Need to Know - MTMIC

By Chris Demeter, Sr. Loss Control Representative

Goto SINOTOOLS to know more.

If I inspect a tool & die shop, I would more than likely find at least one bench or pedestal grinder. If you went into my garage, you would find a pedestal grinder that comes in handy when I need to sharpen my lawnmower blades, mine has three. These grinders come in many styles, sizes, and designs. Typical bench and pedestal grinders often have two abrasive wheels, or one abrasive wheel, and one specialpurpose wheel such as a wire brush, a buffing wheel, or a sandstone wheel.

Grinders operate at very high speeds – the wheels often rotate at several thousand RPMs. If a grinding wheel shatters while in use, the fragments can travel more than 300 mph, so there’s a risk for serious injury from flying fragments and the rotating wheel assemblies (including the flange, spindle end, and nut). Abrasive wheels used on bench and pedestal grinders must be equipped with safety guards. The safety guard encloses most of the wheel — covering the flange, spindle end, and nut projection — while allowing maximum exposure of the wheel periphery. The exposed surface of the wheel should not exceed 90 degrees or one-fourth of the periphery.

Because the safety guard is designed to restrain the pieces of a shattered grinding wheel, the distance between the safety guard and the opening at the top of the wheel must not be more than 1⁄4-inch. If the distance is greater than 1⁄4-inch, then an adjustable “tongue guard” must be installed to protect workers from flying fragments if the wheel shatters. The tongue guard must be adjusted to maintain a maximum 1⁄4- inch distance between it and the wheel. An adjustable work rest must also be installed and adjusted to maintain a maximum clearance of 1⁄8-inch between it and the wheel. This prevents the operator’s hands or the work from being jammed between the wheel and the rest.

All abrasive wheels must be inspected and “ring-tested” before they are mounted to ensure that they are free from cracks or other defects. Wheels should be tapped gently with a light, nonmetallic instrument. A stable and undamaged wheel will give a clear metallic tone or “ring.” It’s a good idea for the operator to stand to the side of the machine when powering it on in case a crack or defect was not detected when the wheel was inspected. If the wheel happens to shatter, the particles will be less likely to strike you. The spindle speed of the machine must also be checked before mounting the wheel to be certain that it does not exceed the maximum operating speed marked on the wheel. Abrasive wheels used on bench and pedestal grinders must be equipped with safety guards.

The OSHA standard for grinders, OSHA 29 CFR .215, is one of the most frequently cited violations issued during a MIOSHA safety inspections. Improperly adjusted work rests and tongues on the grinder are the main reasons for the citation. Abrasive wheel grinders are great machines, but careless operation can injure your hands, fingers, eyes, and respiratory system. The fact that OSHA finds so many abrasive wheel grinder violations every year should be a warning to all of us. Remember that the most common violations—and serious hazards—are failing to properly adjust the safety guards and the work rests. A wheel that fragments at high speed can cause severe personal injury and possibly death.

Lastly, make certain you have no loose-fitting clothing, gloves, jewelry, hair, or other items dangling as you operate the grinder or any other rotating equipment. If one of those things gets tangled up in the revolving grinder wheel, an injury is almost certain to occur. I always recommend posting signs out in the shop as a visual reminder. “Due to the possibility of entanglement, gloves, loose clothing, jewelry, and long hair should never be worn while operating any rotating device.”

If you have a question about these precautions to take when operating a pedestal or bench grinder, please be sure to contact your Loss Control consultant.

• Carbide-tipped cutting tools

• Glass

  For more abrasive grinding wheel manufacturersinformation, please contact us. We will provide professional answers.

• Ceramics

When used correctly, diamond wheels allow for high stock removal rates and high precision without the fear of burning the surface or cracking the workpiece. Our diamond wheels are made with synthetic poly-crystalline or mono-crystalline diamonds, offering hardness and thermal conductivity equal to (or higher than) that of natural diamonds.

While the abrasive material and coating type are essential to manufacturing the right diamond grinding wheel for the job, you should also prioritize selecting the proper bond for your intended application.

Our proven bond systems lock in carefully selected diamond abrasive powders to ensure there is almost zero diamond pull-out. We utilize a careful engineering process that produces a long-lasting, sharp, and durable grinding wheel.

While not as common or adaptable as CBN or diamond wheels, CDX wheels deserve to be mentioned. Specially formulated to grind tungsten carbide and steel simultaneously, CDX wheels contain the mixing of CBN and diamond powders required to grind dissimilar materials (C for CBN, D for Diamond, and X to signify the mixture).

Tools such as carbide-inlaid profiling knives, Bac-Pac systems, and special-tipped tools can be ground quickly while reducing wheel loading and thermal damage to the tool material.

Many technical factors must be considered when choosing the right grinding wheel. Using the wrong wheel can negatively impact your production and final results. With these factors in mind, having dedicated support from an engineer is invaluable. Most grinding wheel suppliers tend to locate a requested wheel in the catalog or inventory and ship it over if available, but that doesn’t mean that it will be the most efficient wheel for your application.

What should you look for in a grinding wheel supplier?

Look for experienced engineers who are committed to their customer’s success and will guide you through the process. Whether you know exactly what you need or are starting from scratch, the right supplier will be eager to adjust their product recommendations as your needs and operations evolve.

Are you interested in learning more about China tool sets? Contact us today to secure an expert consultation!