Conditioning of Diamond and CBN Grinding Wheels
By conditioning, we refer to both dressing and truing of the wheel. In many cases, only the combination of these two processes achieves the best results.
Dressing an abrasive wheel is a delicate operation. Dressing restores the cutting ability of the abrasives on the wheel's surface. It occurs after balancing or when the wheel's surface becomes loaded, glazed, or loses its cutting ability. In practice, dressing a wheel involves restoring the original cutting geometry and correcting flatness and ovality defects.
Dressing removes undesirable residues from the wheel's surface and a small amount of the bonding material. This exposes the abrasives, allowing for effective cutting and restoring the original geometry.
For dressing resin, vitrified, metal, and metal-ceramic bonded wheels, traditional silicon carbide (SIC) dressing wheels are used. The choice of SIC dressing wheel in terms of grit and hardness depends on the grit size of the diamond or CBN wheel to be dressed.
In general, dressing should always be done with coolant. In case it is not possible, a finer grit should be chosen. The same applies to dressing wheels with a low-angle abrasive layer, such as pointed profile wheels.
Dressing
The concentricity of the dressing wheel should be checked before each use. The runout of such a wheel should never exceed 0.01 mm. Especially for fine-grit dressing wheels (320 grit or finer), as perfect concentricity as possible is crucial for results on a diamond or CBN wheel.
As with grinding processes, dressing results depend to a large extent on parameters. Our recommendations are as follows :
Indicative values :
- Dressing wheel speed: 30 m/s
- Speed of the diamond or CBN wheel to be dressed: 1 m/s
- Dressing depth for rough dressing: 0.02–0.05 mm
- Dressing depth for finish dressing: 0.01–0.02 mm
We recommend always dressing in the opposite direction. The dressing wheel's lifetime will be improved, and the treated tool will become sharper.
Always use as wide a dressing wheel as possible, making it easier to achieve flat surfaces on the wheel.
During the operation, the SIC dressing wheel should always remain in contact with the wheel being dressed. We recommend protruding from the abrasive layer of the dressed wheel by only half the width of the dressing wheel.
With very wide diamond or CBN wheels, ensure that the approach does not occur only at the outer or extreme points. Occasional approaches in the middle of the abrasive layer prevent a convex geometry of the dressed abrasive layer.
Specific points to observe on pointed profile wheels
On such wheels, the approach should not occur from the inside of the layer. Also, ensure that the eventual edge of the metal mount touched during dressing does not exceed a width of 1 mm.
Note
The efficiency G in dressing diamond and CBN wheels is between 0.025 and 0.03. This means concretely that the removal of 1 cm3 of abrasive layer from a diamond or CBN wheel requires 30 to 40 cm3 of the SIC dressing wheel. In other words, the wear of the dressing wheel is considerable but entirely normal.
Dressing wheels from our stock
Sharpening
For an abrasive wheel to have optimal cutting qualities, a certain protrusion of the grains is an essential condition. When a wheel has been dressed as described above, the grain protrusion is generally insufficient. After dressing, it is necessary to retract the binder. Conversely to dressing, sharpening stones are used.
Wet the sharpening stones in water or emulsion before use. We advise not the use of cutting oil.
The rotation direction of the wheel should be the same as used in grinding.
