Solutions to grinding problems in tool grinding
Surface finish too rough
Check whether the grinding wheel is running true. Admissible out-of-roundness must not to exceed
0.02 mm. If larger, dress wheel.
Reduce depth of cut ae or feed rate Vfa. Smaller and slower cuts improve the surface finish.
Use a wheel with wider rim section or a finer grain.
Use rigid wheel shapes. Give preference to cup wheels rather than dish wheels.
Increase surface speed.
Toollife too low
- Is the surface speed Vc optimal?
Diamond dry grinding: 10 to 18 m/s (2,000 to 3,600 sfpm)
Diamond wet grinding: 15 to 25 m/s (3,000 to 5,000 sfpm)
CBN dry grinding: 20 to 25 m/s (4,000 to 5,000 sfpm)
CBN wet grinding: 28 to 35 (60) m/s (5,600 to 7,000 [12,000] sfpm)
- Improve overall rigidity. Keep the workpiece overhang as short as possible. Use cup wheels for increased
stability.
- Improve grinding fluid supply. Use neat oil for CBN processes to increase G-ratios. Use low concentration
synthetic fluids for diamond grinding processes, or use low viscosity grinding oil (1.5 to 3 Cst at 40 °C).
Ensure that the grinding fluid actually reaches grinding zone.
- Reduce depth of cut ae or infeed rates Vfa.
- Select harder wheel specifications or higher concentration while observing increase in risk of thermal damage to workpiece.
Vibrations
- Check grinding wheel and wheel arbour for imbalance.
- Improve overall rigidity. Keep the workpiece overhang as short as possible. Use cup wheels for increased stability.
- Check surface speed vc. Low surface speeds make the wheel act softer and, therefore, make it less prone
to vibrations. If the wheel develops a shiny rim section, reduce surface speed or increase feed rate to open up wheel.
- Open and condition grinding wheel with soft aluminium oxide stick.
- Use a wheel body made of vibration dampening material such as graphite, or use a wheel with integrated
vibration dampening centre made of polyurethane.
- Select softer wheel specification or lower concentration.
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