Selecting the right abrasive materials can be challenging when faced with technical terms like "mesh size" and "micron." This guide will clarify these concepts to help you make informed decisions for achieving perfect surface finishes.
What Is Mesh Size?
Imagine examining a precision sieve. Mesh size refers to the number of openings per square inch in a sieve. Higher mesh numbers indicate smaller openings and finer particles that can pass through. Essentially, mesh size serves as a particle's "identification card" for size.
The U.S. Mesh Size (or U.S. Sieve Size) is the industry standard. For example, a 36-mesh sieve has 36 openings per square inch, while a 150-mesh sieve has 150 openings. Therefore, higher mesh numbers correspond to smaller sieve openings and finer particles.
Understanding "+" and "-" Symbols
When describing abrasive particle sizes, you may encounter "+" and "-" symbols:
-
"-" symbol:
Indicates particles are all
smaller
than the specified mesh size. For example, "-100 mesh" means all particles can pass through a 100-mesh sieve.
-
"+" symbol:
Indicates particles are all
larger
than the specified mesh size. For example, "+100 mesh" means all particles are retained by a 100-mesh sieve.
-
"/" or "-":
Indicates particles fall between two mesh sizes. For example, "30/70 mesh" or "30-70 mesh" means particles are smaller than 30 mesh but larger than 70 mesh.
Mesh Size vs. Grit: What's the Difference?
The terms "mesh" and "grit" are often used interchangeably when describing abrasives. In practice, they are largely equivalent. For instance, 60-mesh aluminum oxide might also be called 60-grit aluminum oxide.
Technically, "mesh" describes particles sized close to a sieve's opening, while "grit" more precisely describes particle size distribution. However, for practical purposes, the distinction is negligible.
Mesh Size to Micron Conversion
Understanding the relationship between mesh size and microns is essential. The table below shows approximate conversions:
|
US Mesh
|
Micron (μm)
|
Inches
|
|
4
|
4,750
|
0.187
|
|
5
|
4,000
|
0.157
|
|
6
|
3,350
|
0.132
|
|
7
|
2,800
|
0.111
|
|
8
|
2,360
|
0.0937
|
|
10
|
2,000
|
0.0787
|
|
12
|
1,700
|
0.0661
|
|
14
|
1,400
|
0.0555
|
|
16
|
1,200
|
0.0473
|
|
18
|
1,000
|
0.0394
|
|
20
|
850
|
0.0331
|
|
24
|
690
|
0.027
|
|
30
|
560
|
0.022
|
|
36
|
485
|
0.019
|
|
40
|
425
|
0.016
|
|
46
|
355
|
0.014
|
|
54
|
305
|
0.012
|
|
60
|
250
|
0.01
|
|
70
|
210
|
0.0083
|
|
80
|
165
|
0.0065
|
|
90
|
145
|
0.0057
|
|
100
|
149
|
0.0059
|
|
120
|
125
|
0.0049
|
|
140
|
105
|
0.0041
|
|
150
|
89
|
0.0035
|
|
170
|
88
|
0.0031
|
|
180
|
76
|
0.003
|
|
200
|
75
|
0.0029
|
|
220
|
63
|
0.0025
|
|
240
|
53
|
0.002
|
|
280
|
44
|
0.0015
|
|
320
|
36
|
0.0012
|
|
400
|
23
|
0.00087
|
|
500
|
19
|
0.00075
|
|
600
|
16
|
0.00063
|
|
800
|
12
|
0.00047
|
|
1,000
|
9
|
0.00028
|
|
1,200
|
6
|
0.00024
|
Important note:
These values are approximate because sieve wire thickness affects actual opening sizes. Typically, sizes smaller than 325 mesh are expressed in microns due to manufacturing limitations.
Frequently Asked Questions
What does mesh size mean?
Mesh size indicates the particle size of abrasives.
How is mesh size represented for aluminum oxide or silicon carbide?
Typically shown as a single number representing the average particle size.
How is mesh size represented for glass beads or walnut shells?
Usually shown as two numbers indicating the particle size range.
What's the relationship between particle size and mesh number?
Higher mesh numbers indicate smaller particles - they are inversely related.
What do "+" and "-" symbols mean?
"-" means particles are smaller than the specified mesh; "+" means larger.
How is a particle size range represented?
Two mesh numbers connected by "/" or "-" indicating particles fall between those sizes.
Are "mesh" and "grit" interchangeable?
Yes, particularly when describing abrasive materials.
Is there any practical difference between "mesh" and "grit"?
In commercial applications, the difference is negligible, though "grit" more accurately describes particle size distribution.
Does mesh size affect grinding performance?
Absolutely. Mesh size influences aggressiveness, precision, and material removal rate.
How does understanding mesh size help select appropriate abrasives?
Knowledge of mesh sizes enables informed choices based on application requirements, material removal needs, and desired surface finish.
Which is smaller: 100 mesh or 200 mesh?
200 mesh is smaller. Higher mesh numbers indicate finer particles.
What does 100 mesh mean?
The material has passed through a sieve with 100 openings per square inch, representing the average particle size.
What does 20 mesh mean?
The material has passed through a sieve with 20 openings per square inch, representing the average particle size.
What size is 40 mesh?
The material has passed through a sieve with 40 openings per square inch, representing the average particle size.
What does 30 mesh mean?
The material has passed through a sieve with 30 openings per square inch, representing the average particle size.
Conclusion
Understanding the relationship between mesh sizes and micron measurements is crucial for selecting appropriate abrasive materials. This knowledge helps optimize surface finishing processes and achieve desired results efficiently.
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