Tips for Buying a Grinding Wheel
There are many types of products available for an entire range of grinding applications in metalworking. Ending up with the wrong one can be costly, both in terms of cash and time, so be very careful when making a choice.
When shopping for a grinding wheel in particular, the first thing to consider is the material to be ground. This will tell you the type of abrasive that you’ll need in the wheel.
For steels and steel alloys, for instance, aluminum oxide or zirconia alumina works great. A silicon carbide abrasive is the best for cast iron and non-ferrous metals, and also for non-metals.
Grinding hard yet brittle materials is usually done with a fine-grit, soft-grade wheel. Hard materials contradict the force of abrasive grains, dulling them pretty quickly.
Thus, with a combination of a finer grit and a softer grade, abrasive grains can detach as they dull, exposing new, sharp cutting points. A coarse-grit, hard-grade wheel, on the other hand, will be suitable for ductile and easy-to-penetrate materials.
Another consideration for buying a grinding wheel is the amount of stock to be taken out. Since coarser grits can penetrate more and make heavier cuts, stock removal becomes faster too. But if it’s too hard to penetrate through the material, you can go for a slightly finer grit wheel, which tends to cut faster as there are more cutting points that will do the job.
Faster cuts can be achieved using a wheel with vitrified bonds. For smaller stock removal or if finish requirements are higher, choose resin, shellac or rubber bonds.
When deciding on a wheel bond, look into the wheel’s speed in operation too. Vitrified wheels should only run at a maximum of 6,500 surface feet per minute or the bond could break. Organic bond wheels enjoy the most demand, running anywhere from 6,500 to 9,500 surface feet per minute.
If a higher speed is needed, wheels can be custom-made for the specific purpose. Whatever the case, always check the safe operating speed – usually in rpm or sfm – indicated on the wheel or its blotter, and make it a point never to go beyond it.
Yet another consideration to be made when buying a grinding wheel is the contact area between it and the workpiece. A bigger area will necessitate a softer grade and a coarser grit, if only to ensure free gliding cutting action. Now determine the grinding action’s severity, or the pressure that holds the wheel and the workpiece together. Abrasives are made to withstand varying severity levels when grinding steel and its alloys.
The last but no way the least consideration to make is the grinding wheel’s horsepower. Higher grade wheels typically go with higher-horsepower machines. If wheel diameter is greater than horsepower, it is best to use a softer-grade wheel. Otherwise, use a higher-grade wheel.