Surface Finish RMS, Ra, 16 CLA, 5 ISO Custom Steel Plate
Adding Value to Steel Plate Since 1971
Precision Grinding, Inc. Logo 
1-888-WE-GRIND   (1-888-934-7463)
mail@precisiongrinding.com

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

Surface Finish Conversion Example

16 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
 

Surface Roughness Conversion Chart

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"
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(m) 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

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
Less than a 16 CLA reading provides for a smooth, glossy ISO #5 surface finish.
This Ra Meter is reading 15.3 from the -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.
Surface Grinding 4140 machine plates to ISO #5 finish
Surface Grinding the same machined plates as above.
Home Precision Grinding, Inc. Birmingham Alabama 888-WE-GRIND (934-7463)           Copyright December 17, 2008