Grit and Powder Sizing - Description

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Domestic abrasive manufacturers use sieves or screens to size abrasive grain. Both the sieve and the grain size must conform to the American National Standards Institute B74.12. Typical abrasive grain designations such as #8, #16, #36, #60, #120, #180, and #240 would conform to the same size standard regardless from which domestic manufacturer it was purchased. These sizes are referred to as macrogrits.

There is no standard process for sizing abrasive powders. Typically, abrasive powders are water classified, but some manufacturers may use an air classification technique. After a material has been graded to a specific size, there are several different methods that can be used to perform particle size analysis. Consequently, particle size may vary on a given size from one manufacturer to another.

Although sieve size designations such as #280, #320, #400, #500, #600...may be used to identify abrasive powders, they are theoretical screen size numbers because screens are not actually used to classify the material. In this case, as the screen size number gets higher, the size of the material is finer. Abrasive powders commonly refer to any size finer than #240 grit, and are called microgrits. Each mesh size has an equivalent micron size designation, i.e. 37, 29, 17, 13, 9, 5, 7, 3. As the micron size number gets lower, the size of the material is finer.

Grit and Powder Sizing - Table of Grit Sizes

GRIT SIZING FOR ALUMINUM OXIDES AND SILICON CARBIDES
Grit / Sieve Size	Inches / mm (avg.)	Microns (avg.)
12	0.063 / 1.600	1600
16	0.043 / 1.092	1092
20	0.037 / 0.939	940
24	0.027 / 0.685	686
30	0.022 / 0.558	559
36	0.019 / 0.482	483
46	0.014 / 0.355	356
54	0.012 / 0.304	305
60	0.010 / 0.254	254
70	0.008 / 0.203	203
80	0.0065 / 0.165	165
90	0.0057 / 0.144	145
100	0.0048 / 0.121	122
120	0.0040 / 0.101	102
150	0.0035 / 0.088	89
180	0.0030 / 0.076	76
220	0.0025 / 0.063	63
240	0.0020 / 0.050	50

Grit and Powder Sizing - Table of Powder Sizes

SIZING FOR ALUMINUM OXIDES AND SILICON CARBIDES IN MICRONS (um) (Based on the FEPA standard)
Powder Size	Microns (Avg.)
280	37
320	29
360	23
400	17
500	13
600	9
800	7
1000	5
1200	3