The closer tolerance classes outlined below should not
be specified unless required by the final application
and they should be restricted to critical dimensions.
The closer tolerances demanded, the tighter
the control must be exercised during manufacture,
resulting in higher costs.
When particular physical
properties are required in the products, it
is not always possible to provide them in a
combination which is capable of fabrication
to close tolerances. It is necessary, in these
circumstances, that consultation take place
between the customer and supplier. In general,
softer materials need greater tolerances than
harder ones. Where close tolerances are required,
a specific technique of measurement should be
agreed upon between purchaser and manufacturer.
Tolerances
for outside (O.D.) diameters, inside (I.D.)
diameters, wall thickness, width, height, and
general cross sectional dimensions or extrusions.
RMA Class
1
High
Precision
2
Precision
3
Commercial
Drawing
Designation
E1
E2
E3
Dimensions (In Millimeters)
Above
Up
to
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
±
0.20
±
0.25
±
0.35
±
0.40
±
0.50
±
0.70
±
0.80
±
1.00
±
1.30
±
0.25
±
0.35
±
0.40
±
0.50
±
0.70
±
0.80
±
1.00
±
1.30
±
1.60
±
2.00
±
0.40
±
0.50
±
0.70
±
0.80
±
1.00
±
1.30
±
1.60
±
2.00
±
2.50
±
3.20
RMA
Class
1
High
Precision
2
Precision
3
Commercial
Drawing
Designation
E1
E2
E3
Dimensions
(In Inches)
Above
Up
to
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
±
0.008
±
0.010
±
0.014
±
0.016
±
0.020
±
0.027
±
0.031
±
0.039
±
0.051
±
0.010
±
0.014
±
0.016
±
0.020
±
0.027
±
0.031
±
0.039
±
0.051
±
0.063
±
0.079
±
0.015
±
0.020
±
0.027
±
0.031
±
0.039
±
0.051
±
0.063
±
0.079
±
0.098
±
0.126
Note: Tolerances
on dimensions above 100mm (3.94) should
be agreed on by supplier and user. General
cross sectional dimensions below 1mm (0.04)
are impractical. In general, softer materials
and those requiring a post cure need greater
tolerances.
