Surface Grinding
16RMS - 32RMS - 63RMS
Steel Machine Bases
Machine Frames
Machinist Tables
Robot Pedestals
Side Frames
Steel Tables
Steel Workbenches
Foundation Plates
Base Plates
Grout Plates
Gusset Plates
Machine Platforms
Motor Bases
Mounting Plates
Pump Foundations
Sole Plates
Sub Plates
Press Plates
Bolster Plate
Die Shoes
Die Sets
QDC - Quick Change Dies
QCM Quick Change Molds
Steel Molds
Precision Parallels
Riser Blocks
& Pins
Carbon / Alloy Plate
A36
Steel Plate
HRS Hot Roll Plate
A514-T1 High Strength
A516
Pressure Vessel
A572 GRADE 50
1020 Chemistry
36ksi
1045
HRS Annealed
4140 AN, HRS, PH
Tool Steel & Wear Steel
Metric Plate & Bar
Structural Tubing 2"- 4"
Ground Machined Plates |
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16 µ in. Center Line Average (CLA)
A very smooth, glossy Surface Finish
RMS
is defined as the Root Mean Square
Ra
= Roughness height, average in microns
CLA
= Center Line Average in microinches
N
= New ISO scale numbers
Let's convert
Ra (metric surface finish) to CLA
(0.4
Ra)/ 0.025 = 16 CLA
(1mm = 0.025 in)
(16 CLA) (1.1) = 17.6 RMS
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Surface Roughness Conversion Chart
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| ISO N |
Ra |
CLA |
RMS |
Cut-off |
| 4 |
0.2 |
8 |
8.8 |
0.01" |
| 5 |
0.4 |
16 |
17.6 |
0.01" |
| 6 |
0.8 |
32 |
35.2 |
0.03" |
| 7 |
1.6 |
63 |
64.3 |
0.03" |
| 8 |
3.2 |
125 |
137.5 |
0.1" |
| 9 |
6.3 |
250 |
275 |
0.1" |
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ISO N = new ISO scale
Ra = Roughness Average, microns
CLA = Center Line Roughness Average, microinches
RMS = Root mean square in microinches
Cut-off = The length to be measured across the surface
Multiply Ra(µm) x 40 = CLA (microinches)
Multiply CLA x 1.1 = RMS * (acceptable 1.1 - 1.7 factor)
Converting CLA to RMS is not a perfect science. RMS is based
upon a Sin wave pattern formula, while CLA is measured across a
Sawtooth pattern of peaks and troughs.
Reference: Grindwell Norton, Ltd. Saint-Gobain Abrasives
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Standard Surface Grinding Roughness
REFERENCE:
Old 16 RMS - 32 RMS ►
New ISO #5 - ISO #6
Standard
Blanchard Grinding Roughness REFERENCE:
Old 48- 96 RMS
► New ISO #6 -
ISO #8 |
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| This Ra Meter is reading 15.3 from the
µ-inch scale, while providing a measurement across a 0.03"
cut-off length. This is a 16 Surface Roughness measurement
generally accepted in the field, whether referred to as a 16
surface roughness, 16 Ra, 16 RMS, 16 Rq, 16 CLA, or a #5 ISO
finish. |
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Surface
Grinding the same machined plates
as above. |
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