RMA TOLERANCES TABLES

January 25, 2016 RMA

The Rubber Manufacturers Association (RMA) has developed tolerance tables with ranges to provide communication between user and provider across a wide range of industries. These are helpful when designing and producing a part. You can also consult the RMA article on factors affecting tolerances of molded rubber products.

Metric Tolerances (mm)


Nominal Dimension A1 A2 A3 A4
above up to and





including
Fixed Closure Fixed Closure Fixed Closure Fixed Closure
0 10 0.1 0.13 0.16 0.2 0.2 0.32 0.32 0.8
10 16 0.13 0.16 0.2 0.25 0.25 0.4 0.4 0.9
16 25 0.16 0.2 0.2 0.32 0.32 0.5 0.5 1
25 40 0.2 0.25 0.32 0.4 0.4 0.63 0.63 1.12
40 63 0.25 0.32 0.4 0.5 0.5 0.8 0.8 1.25
63 100 0.32 0.4 0.5 0.63 0.63 1 1.1 1.4
100 160 0.4 0.5 0.63 0.8 0.8 1.25 1.25 1.6
160 & over





(Multiply by)
x .004 x .005 x .005 x .008 x .008 x .010

Inch Tolerances (in)


Nominal Dimension A1 A2 A3 A4
above up to and





including
Fixed Closure Fixed Closure Fixed Closure Fixed Closure
0 0.40 0.004 0.005 0.006 0.008 0.008 0.013 0.013 0.032
0.40 0.63 0.005 0.006 0.008 0.010 0.010 0.016 0.016 0.036
0.63 1.00 0.006 0.006 0.010 0.013 0.013 0.020 0.020 0.040
1.00 1.60 0.008 0.010 0.013 0.016 0.016 0.025 0.025 0.045
1.60 2.50 0.010 0.013 0.016 0.020 0.020 0.032 0.032 0.050
2.50 4.00 0.013 0.016 0.020 0.025 0.025 0.040 0.040 0.056
4.00 6.30 0.016 0.020 0.025 0.032 0.032 0.050 0.050 0.063
6.30 & over





(Multiply by)
x .004 x .005 x .005 x .008 x .008 x .010

Table 12. Summary of RMA Drawing
Designations Extruded Rubber Products


RMA Class Dimensional Tolerance* Table 13 CutLength Tolerance* Table 16 SplicedLength Tolerance* Table 16 MandrelCured* Table 20
1 E1 L1 S1 EN1
2 E2 L2 S2 EN2
3 E3 L3 S3 EN3
4

Table 13. Standard Cross-Sectional Tolerance


RMA Class

1 – High Precision

2 – Precision

3 – Commercial

Drawing Designation
E1 E2 E3
Dimensions (in Millimeters)
Above Up to and including
0 1.5
1.5 2.5
2.5 4.0
4.0 6.3
6.3 10
10 16
16 25
25 40
40 63
63 100
+0.15 +0.25 +0.40
0.20 0.35 0.50
0.25 0.40 0.70
0.35 0.50 0.80
0.40 0.70 1.00
0.50 0.80 1.30
0.70 1.00 1.60
0.80 1.30 2.00
1.00 1.60 2.50
1.30 2.00 3.20

RMA Class

1 – High Precision 2 – Precision 3 – Commercial
Drawing Designation
E1 E2 E3
Dimensions (in Inches)
Above Up to and including
0 0.06
0.06 0.10
0.10 0.16
0.16 0.25
0.25 0.39
0.39 0.63
0.63 0.98
0.98 1.57
1.57 2.48
2.48 3.94
+0.006 +0.010 +0.015
0.008 0.014 0.020
0.010 0.016 0.027
0.014 0.020 0.031
0.016 0.027 0.039
0.020 0.031 0.051
0.027 0.039 0.063
0.031 0.051 0.079
0.039 0.063 0.098
0.051 0.079 0.126

Table 16. Cut Length tolerance for unspliced extrusion


RMA Class

1 – HighPrecision 2 – Precision 3 – Commercial
Drawing Designation.
L1 L2 L3
Length (in Millimeters)
Above Up to and including
0 40
40 63
63 100
100 160
160 250
250 400
400 630
630 1000
1000 1600
1600 2500
2500 4000
4000
+0.7 +0.04 +1.6
0.08 1.3 2.0
1.0 1.6 2.5
1.3 2.0 3.2
1.6 2.5 4.0
2.0 3.2 5.0
2.5 4.0 6.3
3.2 5.0 10.0
4.0 6.3 12.5
5.0 10.0 16.0
6.3 12.5 20.0
0.16% 0.32% 0.50%
Length (in Inches)
Above Up to and including
0 1.6
1.6 2.5
2.5 4.0
4.0 6.3
6.3 10.0
10.0 16.0
16.0 25.0
25.0 40.0
40.0 63.0
63.0 100.0
100.0 160.0
160.0
+0.03 +0.04 +0.06
0.03 0.05 0.08
0.04 0.06 0.10
0.05 0.08 0.13
0.06 0.10 0.16
0.8 0.13 0.20
0.10 0.16 0.25
0.13 0.20 0.40
0.16 0.25 0.50
0.20 0.40 0.63
0.25 0.50 0.80
0.16% 0.32% 0.50%

Table 18. Spliced Length Tolerances


RMA
Class

1 – High Precision 2 – Precision 3 – Commercial
Drawing Designation
S1 S2 S3
Millimeters
Above Up to and including
0 250
250 400
400 630
630 1000
1000 1600
1600 2500
2500 over
+302 +3.2 +7.1
4.0 7.1 8.0
5.0 8.0 9.0
6.3 9.0 10.0
8.0 10.0 11.2
10.0 11.2 12.3
012.5 12.5 16.0
Inches
Above Up to and including
0 10
10 16
16 25
25 40
40 63
63 100
100 over
+.13 +.25 +.28
.16 .28 .32
.20 .32 .36
.25 .36 .40
.32 .40 .45
.40 .45 .50
.50 .50 .53

Table 20. Tolerances on Internal Dimensions
of Mandrel-Supported Extrusions


RMA
Class

1
High Precision
2
Commercial
3
Non-Critical
Drawing Designation
EN1 EN2 EN3
Nominal Dimensions
(in Millimeters)
Above Up to and including
0 4
4 6.3
6.3 10
10 16
16 25
25 40
40 63
63 100
100 160
160
+0.20 +0.20 +0.35
0.20 0.25 0.40
0.25 0.35 0.50
0.35 0.40 0.70
0.40 0.50 0.80
0.50 0.70 1.00
0.70 0.80 1.30
0.80 1.00 1.60
1.00 1.30 2.00
0.6% 0.8% 1.2%
Nominal Dimensions
(in Inches)
Above Up to and including
0 0.16
0.16 0.25
0.25 0.40
0.40 0.63
0.63 1.00
1.00 1.60
1.60 2.50
2.50 4.00
4.00 6.30
6.30
+0.008 +0.08 +0.014
0.008 0.010 0.016
0.010 0.014 0.020
0.014 0.016 0.028
0.016 0.020 0.032
0.020 0.028 0.040
0.028 0.032 0.051
0.032 0.040 0.063
0.040 0.051 0.079
0.6% 0.8% 1.2%

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