Precision Grinding.
Abrasive mechanics, wheel dress ratios, and sub-micron surface finish attainment.
The Abrasive Machining Paradigm
Unlike milling or turning which use defined-edge cutting tools, grinding uses an abrasive wheel with thousands of randomly oriented cutting edges. This allows for machining of materials with hardness exceeding 60 HRC, where carbide tools would fail immediately.
Specific Energy and Heat
Grinding has a specific cutting energy (Unit Power) that is often 10x to 20x higher than milling. A vast majority of this energy is converted directly into heat. If coolant delivery is insufficient, the workpiece will suffer from metallurgical burns, altering the grain structure and introducing tensile residual stresses that cause part failure.
Dressing and Truing
As the wheel cuts, the abrasive grains dull (glazing) or the pores fill with workpiece material (loading). A diamond dressing tool must be passed across the wheel to fracture the abrasive grains, exposing sharp new edges (dressing) and restoring perfect concentricity (truing).
- Coarse Dress: Fast traverse rate across the wheel. Leaves an open structure. Cuts aggressively, runs cooler, but leaves a rougher surface finish on the part.
- Fine Dress: Slow traverse rate. Leaves a closed structure. Generates better finishes but greatly increases heat generation and the risk of burning.