How metal-bonded diamond grinding wheels are dressed determines their removal rate and operating life. When they are dressed mechanically, the diamond grains partially lose their sharpness and break away easily.

This results in only moderate grain protrusion, which does not allow the metal-bonded grinding wheel to be used at its optimum operating point. 

However, the tool-sharpening specialist Vollmer — based in Biberach (Germany) and with a UK subsidiary in Nottingham (www.vollmer-group.com) — has equipped its VPulse 500 wire erosion machine with functions that allow it to dress diamond grinding wheels using ‘erosive methods’; and using a hydrocarbon-based dielectric protects the wheel packages’ clamping systems from corrosion.

Stefan Brand, CEO of the Vollmer Group, said: “Metal-bonded diamond grinding wheels are increasingly being used in tool machining.

"To improve their removal rate and operating life, spark eroding is now recommended for wheel dressing — rather than mechanical methods. With the latter, it is not possible to obtain the grain protrusion that ensures a ‘cool grind’.

“With the Vpulse500, Vollmer can effectively ‘kill two birds with one stone’. The ‘tailored’ erosion process removes the metallic binder around the electrically non-conductive diamond grain, resulting in an optimum topography of the abrasive coating.

"More specifically, it means there is high protrusion of diamond grains that have not been mechanically damaged — plus a high grain-retaining force is maintained. Depending on the binder and grain size, the contour accuracy achievable is ±2µm.”

The use of fine eroding wire means that even complex geometries can be machined on a grinding wheel in one set-up; and internal testing at Vollmer has shown that, compared to mechanical dressing methods, the operating life of metal-bonded grinding wheels can be improved significantly — and the material removal rate is also improved significantly as a result of the open-pored grinding wheel with grain-free regions.