Tips for Buying a Grinding Wheel
In the world of metalworking, there are several products that can be used for a whole range of grinding applications. Choosing the wrong one can easily cost you time and money, so make sure you’ve covered everything before making that purchase.
When in the market for a grinding wheel in particular, the material to be ground is the first consideration you should make. This will clue you in on the best type of abrasive for the wheel.
For instance, to grind steels and steel alloys, you should use aluminum oxide or zirconia alumina. For non-metals, cast iron and non-ferrous metals, a silicon carbide abrasive will do.
Hard and brittle materials often need a wheel that has a fine grit size and a softer grade. Hard materials contradict the force of abrasive grains, dulling them pretty quickly.
Therefore, mixing finer grit with softer grade gives rise to fresh, sharp cutting points as the abrasive grains dull and eventually come off. On the other hand, if you plan to grind soft, ductile and easily penetrable materials, you can use a coarse-grit and hard-grade wheel.
Another consideration for buying a grinding wheel is the amount of stock to be taken out. With coarser grits, penetration is deeper and cuts are heavier, which means stock removal is quicker as well. But for materials that are too hard to penetrate, a slightly finer grit wheel can do the trick – and much faster too – thanks to its many cutting points that can do the task.
If you want to cut faster, go for a wheel with vitrified bonds. And if the finishing requirements are higher or if only a small amount of stock is to be removed, rubber, shellac and resin bonds are your best options.
Another thing you should consider when choosing a wheel bond is wheel’s speed while in operation. Vitrified wheels should only run at a maximum of 6,500 surface feet per minute or the bond could break. Popular choices are organic bond wheels that run from 6,500 to 9,500 surface feet per minute.
For higher speeds, customized wheels are needed. In any case, the safe operating speed – most probably in sfm or rpm – indicated on the wheel or its blotter must never be exceeded.
Next to consider is the area of grinding contact between the wheel and the workpiece. The bigger the area, the coarser the grit and the softer the grade must be to achieve a smooth cutting action. Now check the grinding action severity (how much pressure is keeping the wheel and the material together). Take note that some abrasives can withstand more severe grinding conditions than others.
Finally, look into the grinding wheel’s horsepower. In most cases, higher grade wheels are used with machines with higher horsepower. A softer grade wheel is better to use if wheel diameter exceeds horsepower. Otherwise, a harder grade wheel fits well.