Superfinishing uses fine grit sized materials to achieve the desired finish.

The sizing of abrasive grains is determined by organizations such as the Federation of European Abrasive Products (FEPA), and the Japanese Industrial Standards Committee (JIS). Most superfinishing processes use conventional abrasives with grit sizes between 400 and 1200 grit on the FEPA scale. Some applications, such as miniature bearings, may require the use of sub-micron sized particles. Generally, the use of finer grit sizes will improve surface finishes. The table shown in this paragraph compares the nominal grain sizes of conventional abrasive particles using the FEPA and JIS standards.

Grain Sizes

FEPAJISMicron
32050035
40070023
500100018
600120014
80020008
100030005
120040003
150060001

Superabrasive applications which require heavier stock removal utilize larger grit sized abrasive grains. The sizing of larger abrasive grains is also determined by international standards organizations, and the table below shows a comparison of FEPA, mesh, and micron sizing for some common larger abrasive grains.

Grain Sizes

FEPAMeshMicron
D42640/50426 µm
D35645/50356 µm
D30150/60301 µm
D25160/70251 µm
D21370/80213 µm
D18180/100181 µm
D151100/120151 µm
D126120/140126 µm
D107140/170107 µm
D91170/20091 µm
D76200/23076 µm
D64230/27064 µm
D54270/32554 µm
D46325/40046 µm