How to Choose a Grinding Wheel
There are many companies offering grinding wheels for metalworking applications. But you need to pick the right one so you don’t end up wasting cash and time.
Many things should be considered when buying a grinding wheel, first of which is the material that you will use it on. This determines the type of abrasive you will need. For example, for steel alloys, zirconia alumina is a good choice. If you plan to use your grinder for non-metallics, cast iron and non-ferrous metals, experts advise silicon carbide abrasive.
The harder and more brittle the material to be ground is, the softer the grade and the finer the grit size you’ll need. That’s because harder materials resist abrasive grains, which makes them dull fast. The finer grit and softer grade formula works because the grains separate once they have dulled, and fresh, sharp cutters are exposed on the surface. Conversely, because softer and more ductile materials resist penetration less, a coarser grit and harder grade are more suitable to use.
The amount of stock that should be removed is also a factor. Due to heavier cuts and stronger penetration, coarser grits will obviously take out stock at a higher speed. But a finer grit will be more effective for softer material.
As to bonds, wheels with vitrified bonds, they are capable of higher-speed cutting. If a small amount of stock should be removed, rubber, resin or shellac bonds should be used.
Another thing that makes a difference when choosing a wheel bond is how fast the wheel turns in operation. Vitrified wheels often run under 6,500 surface feet per minute. Higher speeds may cause the vitrified bond to break. When speeds reach 6,500 to 9,500 surface feet per minute, organic bond wheels are recommended. High-speed applications normally require specially designed wheels.
In any case, maximum operating speed limits indicated on the wheel or its blotter must not be exceeded.
The next issue to look into is the area of the grinding contact between wheel and the material being ground. Broader areas of contact mean a coarser grit and softer grade should be used. Finer grits and harder grades are a must for smaller areas of grinding contact because of the greater unit pressure.
Next thing to check is grinding action severity. This is the pressure responsible for keeping the grinding wheel close to the workpiece. Certain abrasives are designed for severe grinding conditions, such as when grinding steel and steel alloys.
Finally, machine horsepower should be considered too. Higher-horsepower machines often work with harder-grade wheels.If horsepower is less than wheel diameter, a softer grade wheel is advised. The reverse is also true.
The opposite is true as well.