For diamond or CBN wheels, in most cases the outer diameter of the wheel depends on the grinding machine. So we generally use the size recommended by the machine manufacturer, but if we can make or modify the machine ourselves, or the outer diameter can be set freely, then it is difficult to decide which size to use.
In general, a diamond grinding wheel with an outer diameter of d300mm has a higher grinding ratio and longer service life than a diamond wheel with an outer diameter of d100mm. Of course, larger diamond grinding wheels will be more expensive, in some cases three times the size, but not simply three times the price. However, if you carefully calculate the grind ratio and cost, this can be advantageous in terms of money. The grinding ratio here is the value obtained by dividing the grinding amount by the wear amount of the grinding wheel, for example, the value indicating how many workpieces can be ground and polished by the diamond layer of a 1 cc grinding wheel.
In terms of grinding ratio, other factors being the same, the larger the outer diameter, the higher the grinding efficiency. In addition, the wider and thicker the grinding layer, the higher the grinding ratio. However, grinding may not be successful if the outer diameter is increased unnecessarily.
When it is better to increase the outer diameter of the grinding wheel:
The grinding wheel wears quickly, the shape collapses quickly, and the accuracy cannot be achieved.
Insufficient peripheral speed
Large grinding area and large workpiece size.
When is it better to make it smaller:
Grinder motor output and torque are insufficient.
The grinding wheel is hard, does not cut, and is not sharp.
Large runout and dimensional accuracy cannot be obtained.
When it is better to increase the thickness and width of the abrasive layer:
I want to increase the surface roughness
When the grinding wheel is severely worn
I want to make grinding more efficient (I want to set up a large cross section, cross feed, etc.)
When it is better to reduce the thickness and width of the frosted layer:
Charred on workpiece or wheel
Grinder spindle powder and torque are not enough
I'm going to make a deep cut
When dry or abrasive cannot be used.