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Feature
The importance of ingredient characteristics in master batching
 Have you ever been stuck without a mesh-micron conversion table when you needed to convert a particle size from one unit of measure to the other? I developed a simple formula for converting between standard US mesh sizes and microns that provides high accuracy over a wide particle size range (45 to 400 mesh). I came up with this equation by plotting particle size in microns versus standard US mesh sizes between 80 and 400 and then fitting various Microsoft Excel spreadsheet trendlines to the data. As you can see in Figure 1, there’s an exceptional match between the plotted mesh sizes (in red) and the power function trendline (in black) that’s produced by the following equation: microns = 14,992 × mesh (-1.0046)
Rounding this off creates an easy-to-remember equation, which I call the Kirk Mesh Equation: microns = 15,000⁄mesh. This can be also be written as mesh = 15,000⁄microns.
If this equation seems too simplistic, take a closer look at how accurate it is for converting mesh sizes between 45 and 400 to microns, as shown in Table I. While the conversion accuracy is poor for mesh sizes below 45, the equation provides very reasonable accuracy (5.9 percent or less error) for standard US mesh sizes from 45 to 400 when compared with typically published micron particle sizes for these mesh sizes.
Inch-mesh conversions.
You can also convert between inches and mesh sizes using this equation:
inches = 0.6⁄mesh
(or mesh = 0.6⁄inches)
This equation provides a conversion error of 7.6 percent or less over the 45- to 400-mesh range.
TABLE 1
Accuracy of Kirk Mesh Equation
Particle size (microns)
|
| Standard US mesh size |
Value most often published in conversion charts |
Value calculated with Kirk Mesh Equation |
Difference (percent) between published and calculated values |
| 10 |
2,000 |
1,500 |
-25.0 |
| 20 |
841 |
750 |
-10.8 |
| 30 |
595 |
500 |
-16.0 |
| 40 |
420 |
375 |
-10.7 |
| 45 |
354 |
333 |
-5.8 |
| 50 |
297 |
300 |
1.0 |
| 60 |
250 |
250 |
0.0 |
| 80 |
177 |
188 |
5.9 |
| 100 |
149 |
150 |
0.7 |
| 120 |
125 |
125 |
0.0 |
| 140 |
105 |
107 |
2.0 |
| 170 |
88 |
88 |
0.3 |
| 200 |
74 |
75 |
1.4 |
| 230 |
63 |
65 |
3.5 |
| 270 |
53 |
56 |
4.8 |
| 325 |
44 |
46 |
4.9 |
| 400 |
37 |
38 |
1.4 |
Don Kirk, is a senior project engineer at Magnequench International Inc., a company of Molycorp. He has worked as an electrical engineer with the company for 22 years.
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