Diamond Tools: How to Choose Diamonds' Grit

When choosing the diamonds’ grit of a diamond tool, we should consider the workpieces’ roughness requirement, the tool’s cutting/grinding efficiency and the best grit range of the tool’s bond.

Generally, diamond tools with coarse diamond grit have high processing efficiency but will also leading to high processing roughness; diamond tools with fine diamond grit is opposite. For a same roughness requirement, the grit of super-abrasives is finer than the normal-abrasives’. Under the premise of satisfying the roughness requirements, we should choose coarser grit to improve processing efficiency.

Different bonds of diamond tools have different hold capacities to the diamonds. For a certain bond, there is a best grit range. Normally, the best grit for resin bond is finer than 100/120, ceramics bond is 100/120 – 170/200, and metal bond is 70/80 – 230/270.

In addition, metal-plated diamonds have a lower processing roughness, so their grit can be coarser.

Below are two tables we can refer to when choosing the diamonds’ grit for diamond tools:

The Relationship of Diamonds’ Grit and Surface Roughness

Grit Number	Surface roughness Ra/μm
	Resin Bond	Metal Bond
80/100 – 100/120	-	0.32 – 2.5
100/120 – 170/200	0.16 – 0.63	0.16 – 1.25
170/200 – 270/325	0.08 – 0.32	0.16 – 0.63
325/400 – M10/20	0.04 – 0.16	-
M8/12 – M4/8	0.02 – 0.08	-
M4/8 – M1.5/3	0.01 – 0.04	-

Grit Choosing in Different Processing Procedures

Processing Procedure	Grit Range
Coarse grinding	80/100 – 120/140
Half-fine grinding	120/140 – 200/230
Fine grinding	200/230 – M36/54
Polishing	M22/36 – M0.5/1.5

I also list some other points in my another article which also need to be considered.