The Rubber Manufacturers Association (RMA) has developed standard tolerance specifications for rubber products with permissible ranges for clarity between user and provider/manufacturer across a wide range of industries. These are helpful when designing and manufacuring elastomer components. You can review these RMA tolerance tables below for your design considerations.
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 (mm)
Nominal Dimension | A1 | A2 | A3 | A4 | |||||
---|---|---|---|---|---|---|---|---|---|
Above | Up to and including | Fixed | Closure | Fixed | Closure | Fixed | Closure | Fixed | Closure |
0 | 0.4 | 0.004 | 0.005 | 0.006 | 0.008 | 0.008 | 0.013 | 0.013 | 0.032 |
0.4 | 0.63 | 0.005 | 0.006 | 0.008 | 0.01 | 0.01 | 0.016 | 0.016 | 0.036 |
0.63 | 1 | 0.006 | 0.006 | 0.01 | 0.013 | 0.013 | 0.02 | 0.02 | 0.04 |
1 | 1.6 | 0.008 | 0.01 | 0.013 | 0.016 | 0.016 | 0.025 | 0.025 | 0.045 |
1.6 | 2.5 | 0.01 | 0.013 | 0.016 | 0.02 | 0.02 | 0.032 | 0.032 | 0.05 |
2.5 | 4 | 0.013 | 0.016 | 0.02 | 0.025 | 0.025 | 0.04 | 0.04 | 0.056 |
4 | 6.3 | 0.016 | 0.02 | 0.025 | 0.032 | 0.032 | 0.05 | 0.05 | 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-Selection Tolerance
RMA Class | 1 – High Precision | 2 – Precision | 3 – Commercial | |
---|---|---|---|---|
Drawing Designation | E1 | E2 | E3 | |
Dimensions (in Millimeters) | ||||
Above | Up to | |||
0 | 1.5 | 0.15 | 0.25 | 0.4 |
1.5 | 2.5 | 0.2 | 0.35 | 0.5 |
2.5 | 4 | 0.25 | 0.4 | 0.7 |
4 | 6.3 | 0.35 | 0.5 | 0.8 |
6.3 | 10 | 0.4 | 0.7 | 1 |
10 | 16 | 0.5 | 0.8 | 1.3 |
16 | 25 | 0.7 | 1 | 1.6 |
25 | 40 | 0.8 | 1.3 | 2 |
40 | 63 | 1 | 1.6 | 2.5 |
63 | 100 | 1.3 | 2 | 3.2 |
RMA Class | 1 – High Precision | 2 – Precision | 3 – Commercial | |
Drawing Designation | E1 | E2 | E3 | |
Dimensions (in Inches) | ||||
Above | Up to | |||
0 | 0.06 | 0.006 | 0.01 | 0.015 |
0.06 | 0.1 | 0.008 | 0.014 | 0.02 |
0.1 | 0.16 | 0.01 | 0.016 | 0.027 |
0.16 | 0.25 | 0.014 | 0.02 | 0.031 |
0.25 | 0.39 | 0.016 | 0.027 | 0.039 |
0.39 | 0.63 | 0.02 | 0.031 | 0.051 |
0.63 | 0.98 | 0.027 | 0.039 | 0.063 |
0.98 | 1.57 | 0.031 | 0.051 | 0.079 |
1.57 | 2.48 | 0.039 | 0.063 | 0.098 |
2.48 | 3.94 | 0.051 | 0.079 | 0.126 |
Table 16. Cut Length Tolerance for unspliced extrusion
RMA Class | 1 – High Precision | 2 – Precision | 3 – Commercial | |
---|---|---|---|---|
Drawing Designation | E1 | E2 | E3 | |
Dimensions (in Millimeters) | ||||
Above | Up to | |||
0 | 40 | 0.7 | 0.04 | 1.6 |
40 | 63 | 0.08 | 1.3 | 2 |
63 | 100 | 1 | 1.6 | 2.5 |
100 | 160 | 1.3 | 2 | 3.2 |
160 | 250 | 1.6 | 2.5 | 4 |
250 | 400 | 2 | 3.2 | 5 |
400 | 630 | 2.5 | 4 | 6.3 |
630 | 1000 | 3.2 | 5 | 10 |
1000 | 1600 | 4 | 6.3 | 12.5 |
1600 | 2500 | 5 | 10 | 16 |
2500 | 4000 | 6.3 | 12.5 | 20 |
4000 | 0.16% | 0.32% | 0.50% | |
Length (in Inches) | ||||
Above | Up to | |||
0 | 1.6 | 0.03 | 0.04 | 0.06 |
1.6 | 2.5 | 0.03 | 0.05 | 0.08 |
2.5 | 4 | 0.04 | 0.06 | 0.1 |
4 | 6.3 | 0.05 | 0.08 | 0.13 |
6.3 | 10 | 0.06 | 0.1 | 0.16 |
10 | 16 | 0.8 | 0.13 | 0.2 |
16 | 25 | 0.1 | 0.16 | 0.25 |
25 | 40 | 0.13 | 0.2 | 0.4 |
40 | 63 | 0.16 | 0.25 | 0.5 |
63 | 100 | 0.2 | 0.4 | 0.63 |
100 | 160 | 0.25 | 0.5 | 0.8 |
160 | 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 | ±302 | ±3.2 | ±7.1 |
0 | 250 | 4 | 7.1 | 8 |
250 | 400 | 5 | 8 | 9 |
400 | 630 | 6.3 | 9 | 10 |
1000 | 1600 | 8 | 10 | 11.2 |
1600 | 2500 | 10 | 11.2 | 12.3 |
2500 | over | 12.5 | 12.5 | 16 |
Inches | ||||
Above | Up to | |||
0 | 10 | 0.13 | 0.25 | 0.28 |
10 | 16 | 0.16 | 0.28 | 0.32 |
16 | 25 | 0.2 | 0.32 | 0.36 |
25 | 40 | 0.25 | 0.36 | 0.4 |
40 | 63 | 0.32 | 0.4 | 0.45 |
63 | 100 | 0.4 | 0.45 | 0.5 |
100 | over | 0.5 | 0.5 | 0.53 |
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 | |||
0 | 4 | 0.2 | 0.2 | 0.35 |
4 | 6.3 | 0.2 | 0.25 | 0.4 |
6.3 | 10 | 0.25 | 0.35 | 0.5 |
10 | 16 | 0.35 | 0.4 | 0.7 |
16 | 25 | 0.4 | 0.5 | 0.8 |
25 | 40 | 0.5 | 0.7 | 1 |
40 | 63 | 0.7 | 0.8 | 1.3 |
63 | 100 | 0.8 | 1 | 1.6 |
100 | 160 | 1 | 1.3 | 2 |
160 | 0.60% | 0.80% | 1.20% | |
Nominal Dimensions (in Inches) | ||||
Above | Up to | |||
0 | 0.16 | 0.008 | 0.08 | 0.014 |
0.16 | 0.25 | 0.008 | 0.01 | 0.016 |
0.25 | 0.4 | 0.01 | 0.014 | 0.02 |
0.4 | 0.63 | 0.014 | 0.016 | 0.028 |
0.63 | 1 | 0.016 | 0.02 | 0.032 |
1 | 1.6 | 0.02 | 0.028 | 0.04 |
1.6 | 2.5 | 0.028 | 0.032 | 0.051 |
2.5 | 4 | 0.032 | 0.04 | 0.063 |
4 | 6.3 | 0.04 | 0.051 | 0.079 |
6.3 | 0.60% | 0.80% | 1.20% |