This is usually the order of the day! But sometimes the wheel specification just doesn't do it on the heat treated alloy steels that you are grinding.
example: You are using an 8" x 1/2" x 1-1/4" 38A white wheel and are dry surface grinding some D2, heat treated steel. Today, there are more advanced wheels than the traditional premium 38A white wheel. Norton's 32A or 32AA or one of the newer ceramic wheels made with 3M's CUBITRON® will improve this application. The sharpness and action maintained by the 3M CUBITRON® abrasive reduces grinding time and increases stock removal.
Typically, a 46 grit G, H, or I hardness and an 8 structure (porosity) would be used. A new 8" wheel spinning at 2600 RPM is grinding at 5500 SFPM (Surface Feet Per Minute). This is a good surface speed. But if the grinder spindle is spinning at 3600 RPM, the wheel will create too much friction and heat at this high speed. What would work more effectively?
First, use a grinding speed control to slow the wheel RPM's down or put on a smaller diameter wheel. Second, select a ceramic grit 3M CUBITRON® abrasive wheel. Third, balance the wheel. Forth, dress the wheel so it has an aggressive, cool action.
Dressing should be done normally at the infeed rate of .001 maximum. Any infeed of the diamond dressing tool, (ALL TYPES), greater than .001 will instantly crack and crush the vitrified bond. This is because vitrified bonds cannot withstand external pressure. This excess pressure will crack the surface of the wheel from .006 to .018 deep. Dress several passes to true, straighten, and condition. Then with an infeed of .002 and a very fast traverse, groove the wheel face with a thread form. Use a sharp pyramid shaped diamond single point dressing tool to do this. When done correctly, this will make the wheel grind cool, hungry and aggressive. An added plus would be to install a Sony digital readout for more positive infeed control.
In addition, a "grinding" variable speed control is a must for grinding. It is great! Slow the RPM's down and the wheel grinds freely with less friction and more aggressive action. Speed it up and it holds corners and grinds tighter tolerances. It also can improve surface finish.
Finally, for more mass production and larger chuck loads, look into CBN BORAZON® vitrified wheels for even faster, cooler, longer life, and a more profitable way to grind.
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grinding questions. Call our
Certified Abrasive Engineers.
Harry G. Sachsel C.A.E.