Abrasives

All about the Humble Grinding Wheel Part II

Grinding Wheel

Using Grinding Wheels

Grinding wheels are used with grinding machines. The wheel should be clamped on and fit freely on supporting arbors. (Clamping force should be distributed evenly to transfer the rotary motion to the wheel.) The wheel should not be forced on. The spindle nut should be tightened enough only to hold the wheel on.

To maintain the life of grinding wheels and for optimal use they may be dressed or trued. Though the wheels will self sharpen a wheel or grinding dresser will remove the top layer of abrasive, revealing a fresh, sharp surface. Trueing up a wheel will make it parallel to the grinding table. This will result in the most even and accurate surface. Note that wheels dressed to an eighth of an inch or thinner must be 100 grit or finer to avoid breakage and hold the proper radii.

Grinding wheels should be inspected and ring-tested before mounting and after dressing to ensure that they are free from cracks or defects.

Grinding Wheel Tips

Harder knife steels require softer grinding wheels and vice versa. Slowing down the machine will make a wheel seem softer. The reverse is true. To get a better finish from a roughing wheel apply wax to the wheel. This will temporarily smooth the surface. Also lower the angle back a few degrees and increase the revolutions per minute. The wheel can now buff!

An incorrect coolant ratio is a common source of grinding issues. To little will result in rust; too rich and health risks increase. Use a handheld refractometer to assure the correct ratio.

Grinding Wheel Safety

Grinding machines must be powered by a source that will maintain spindle speed. Never exceed maximum operating speed of the wheel. Wear eye protection. Keep all guards in place. According to OSHA a safety guard "shall cover the spindle end, nut, and flange projections." Although, it may be exposed on portable saws.

Work rests which are rigidly supported and adjustable should be on all floor and bench-mounted grinders. To prevent work from getting stuck between the wheel and the rest there should be a maximum gap of an eighth of an inch. Adjustments should not be made while the wheel is moving.

Please follow the safety rules and guidelines outlined in the Grinding Wheel Institute’s flyer. Your supplier can provide you with these materials. You can also read the OSHA (Occupational Safety & Health Administration) safety guidelines.

Don‚Äôt overlook the humble grinding wheel. With the different types of abrasives, grading, material, grain size, grade, grain spacing, and bond type; there is a lot to choose from. When you choose your grinder, work materials, coolant levels, and operating speed ‚Äď there is a lot to think about. Before your next project, brush up on the safety precautions. Having a healthy level of fear and respect for abrasive grinding and the risk that they come with will go a long way in keeping you safe.

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