Tech Talk
What are the main factors in Vit CBN wheel selection?
The main criteria for material removal rates, form holding and surface quality are the grain size, the concentration, hardness and structure.
A wide range of different grain sizes is used for CBN wheels. High metal removal rates demand coarser grit sizes. Higher surface quality can be achieved by using finer grains. A wide field of application is covered by the grain sizes 76 to 151 (US mesh 200/230 to 100/120).
The wheel may be further optimised to a particular task by varying its hardness. Softer specifications are more suitable for heat-sensitive workpieces. Harder wheels are chosen, among other reasons, when a high degree of form retention is required.
As for conventional vitrified grinding wheels, the structure of vitrified CBN wheels plays a decisive partin the overall grinding performance. Open or induced porosity wheels are chosen for high performance grinding.
Essentially the selection of the most suitable concentration is determined by the size of the contact surface between grinding wheel and workpiece. For OD grinding the concentration should generally be low: about C100. For ID grinding the concentration must be higher: C100 to C150.
