Sharp SH-920 Instruction Manual page 49

(G) PERFECT SURFACE FINISH
Too hard a wheel or wheel is not correctly chosen.
1.
Workpiece is not clamped well.
2.
A dirty mating surface between the spindle taper and wheel flange
3.
(adaptor) bore will make the wheel to vibrate.
An unqualified wheel flange, such as poor concentricity and poor
4.
squareness.
Wheel and flange not matched well or there have somewhat slippage.
5.
An unbalanced wheel or the wheel is not be balanced well.
6.
Wheel won't be well dressed.
7.
The coupling between motor and spindle become loosen or broken.
8.
A defect bearing is used in spindle or motor.
9.
10. Coolant mixing ratio is improper, or too much oil.
< The correct ratio is oil : water=1 : 60-80. >
11. The coolant is dirty. For getting good surface finish the automatic paper
strip filter attachment is recommended.
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