A237, R2-B Bldg., High-tech Ind. Village, Nanshan, Shenzhen

Diamond Grit & Concentration Advisor

Choose your material class and finish target to get a recommended diamond grit (FEPA D) and concentration, with expected surface finish and a CBN warning for ferrous materials.

Technical Disclaimer: Grit and concentration results are starting points for wheel specification only. Actual performance depends on bond type, wheel speed, machine rigidity, coolant and dressing practice, so validate every recommendation with a trial grind before production. Always observe the maximum operating speed marked on the wheel, and select CBN rather than diamond for steel and cast iron.

Material class

Finish target

Finish unit

Recommended grit & concentration

Boundary rule — when not to use diamond

Diamond is the hardest abrasive and the correct choice for hard, brittle, non-ferrous materials such as cemented carbide, ceramics, glass, silicon, sapphire, ferrite, graphite and composites. It must not be used on ferrous metals — steel, cast iron, and their alloys — because carbon in diamond reacts with iron at grinding temperatures (roughly above 700 °C / 1300 °F). This chemical affinity causes rapid, abnormal diamond wear (graphitisation) and destroys the wheel. For steel, hardened steel, cast iron and other ferrous workpieces, use CBN (cubic boron nitride) instead.

Reference: grit and concentration scales

Grit size (FEPA D) sets the surface roughness; concentration sets how much diamond is in the bond, and therefore life and removal capacity. The two are independent.

FEPA D grit	Approx. size	Typical Ra	Typical use
D181	~180 um	0.5-0.8 um	Rough / semi-finish
D151	~150 um	0.4-0.6 um	General roughing
D126	~125 um	0.3-0.5 um	General grinding
D91	~90 um	0.2-0.4 um	Carbide tool grinding
D64	~63 um	0.15-0.3 um	Fine finishing
D46	~45 um	0.1-0.2 um	Precision finish
D30	~30 um	0.05-0.15 um	Fine edge prep
D15	~15 um	<0.05 um	Polishing / lapping

Ra is indicative; bond, coolant, speed and rigidity all shift the result.

Concentration scale

Concentration	Character	Typical use
50%	Freest, coolest cut	Delicate fine finishing
75%	Good finish, moderate life	Precision finishing, ceramics
100%	Balanced (default)	General grinding
125%	Longer life, higher removal	Tool grinding, form work
150%	High removal capacity	Heavy removal, PCD, hard materials
175-200%	Maximum life	Wafer, PCD, special cases

Diamond concentration convention: 100 = 4.4 ct per cubic centimetre of working layer.

Key takeaways for buyers & engineers

Grit (FEPA D) sets the finish; concentration sets life and removal capacity.
Start at 100% concentration and adjust for the material and volume.
For ferrous materials the tool switches to CBN automatically.

Quick selection checklist

Choose material class and finish target.
Read the recommended grit and concentration.
Check the expected Ra against your specification.
Use CBN if the tool shows a ferrous warning.

Need a custom specification? Send your drawing or current wheel marking and we will quote a diamond wheel to fit your material, machine and finish target — OEM, custom and private label supported.