求助：表面粗糙度的关系。RA=1.06um, RMS=1.2um, 150 grit
求助各位大侠：请问这个几个粗糙度的表达方式是什么关系？
RA=1.06UM, RMS=1.2 UM, 150 grit
印象当中粗糙度的等级里面没有1.06的，还有RMS和RA有什么关系和区别？150 grit是指什么？
谢谢！ 顶起来。请大家帮忙啊。。。 Surface roughness can be measured by a profilometer, a stylus device used to trace across the surface profile. The results are expressed either as RA, which is the arithmetic average deviation from the center line of the surface, or as RMS, which is the root mean square of the deviations from the center line. RA or RMSvalues are given in either microns (same as micrometers or µm) or micro-inches (µ"). On drawings, surface roughness is specified as RA in micro-inches. RMS will be approximately 11 percent higher than the RA number for a given surface.
Surface Measurement Comparisons (Meltzer 1993)RMS (microinch)RMS(µm)RA (microinch)RA (µm)Grit Size80 58
47
34
17
14
2.03 1.47
1.2
0.6
0.43
0.36
71 52
42
30
15
12
1.90 1.32
1.06
0.76
0.38
0.30
80 120
150
180
240
320
These values are the average data of many tests. Because of the many variables that create this data, deviations of ±5% would be considered well within good measurement parameters. From Bulletin on Material Welds and Finishers by DCI, Inc. (Meltzer 1993)
Root-Mean-Square【数】均方根(值)
[ 本帖最后由 ivantse 于 2008-1-14 10:51 编辑 ]
What is Grit Size(粒度) in the Sandpaper?
Grit size refers to the size of the particles of abrading materials embedded in the sandpaper. A number of different standards have been established for grit size. These standards establish not only the average grit size, but also the allowable variation from the average. The two most common are the United States CAMI (Coated Abrasive Manufacturers Institute, now part of the Unified Abrasives Manufacturers' Association) and the European FEPA (Federation of European Producers of Abrasives) "P" grade. The FEPA system is the same as the ISO 6344 standard. Other systems used in sandpaper include the Japan Industrial Standards Committee (JIS), the micron grade (generally used for very fine grits). The "ought" system was used in the past in the United States. Also, cheaper sandpapers sometimes are sold with nomenclature such as "Coarse", "Medium" and "Fine", but it is not clear to what standards these names refer.关于磨轮的grit size(From Answers.com)
Size of the abrasive particles on a grinding wheel.
[ 本帖最后由 ivantse 于 2008-1-14 10:59 编辑 ] 以前我一直认为RMS就是微英寸，原来是RA x 1.11 = RMS。伊凡给的资料很好！谢谢！
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