Bruckman Rubber Co. | Since 1961


Fixed dimensions are not affected by flash thickness variations. Closure dimensions are affected by flash thickness variations.

TABLE 1
Drawing Designation "A-1" High Precision

Standard dimensional tolerance table — Molded solid rubber products

Size (inches)

Fixed

Closure

Size (millimeters)

Fixed

Closure

Above Incl.

+/-

Above Incl.

+/-

0 - .40

.004

.005

0 - 10

.10

.13

.40 - .63

.005

.006

10 - 16

.13

.16

.63 - 1.00

.006

.008

16 - 25

.16

.20

1.00 - 1.60

.008

.010

25 - 40

.20

.25

1.60 - 2.50

.010

.013

40 - 63

.25

.32

2.50 - 4.00

.013

.016

63 - 100

.32

.40

4.00 - 6.30

.016

.020

100 - 160

.40

.50

Drawing Designation "A1" is the tightest tolerance classification and indicates a high precision rubber product. Such products require expensive molds, fewer cavities per mold, costly in-process controls and inspection procedures. It is desirable that the exact method of measurement be agreed upon between rubber manufacturer and customer, as errors in measurement may be large in relation to tolerance. Some materials, particularly those requiring post curing, do not lend themselves to Drawing Designation "A-1" tolerances.

TABLE 2
Drawing Designation "A-2" Precision

Standard dimensional tolerance table — Molded solid rubber products

Size (inches)

Fixed

Closure

Size (millimeters)

Fixed

Closure

Above Included

+/-

Above Included

+/-

0 - .40

.006

.008

0 - 10

.16

.20

.40 - .63

.008

.010

10 - 16

.20

.25

.63 - 1.00

.010

.013

16 - 25

.25

.32

1.00 - 1.60

.013

.016

25 - 40

.32

.40

1.60 - 2.50

.016

.020

40 - 63

.40

.50

2.50 - 4.00

.020

.025

63 - 100

.50

.63

4.00 - 6.30

.025

.032

100 - 160

.63

.80

6.30 & over
multiply fixed dimensional tolerances by 0.4%

160 & over
multiple fixed dimensional tolerances by 0.4%

Drawing Designation "A2" tolerances indicate a precision product. Molds must be precision machined and kept in good repair. While measurement methods may be simpler than with Drawing Designation "A-1", careful inspection will usually be required.

TABLE 3
Drawing Designation "A-3" Commercial

Standard dimensional tolerance table — Molded solid rubber products

Size (inches)

Fixed

Closure

Size (millimeters)

Fixed

Closure

Above Included

+/-

Above Included

+/-

0 - .40

.008

.013

0 - 10

.20

.32

.40 - .63

.010

.016

10 - 16

.25

.40

.63 - 1.00

.013

.020

16 - 25

.32

.50

1.00 - 1.60

.016

.025

25 - 40

.40

.63

1.60 - 2.50

.020

.032

40 - 63

.50

.80

2.50 - 4.00

.025

.040

63 - 100

.63

1.00

4.00 - 6.30

.032

.050

100 - 160

.80

1.25

6.30 & over
multiply fixed dimensional tolerances by 0.5%

160 & over
multiple fixed dimensional tolerances by 0.5%

Drawing Designation "A3" tolerances indicate a "commercial" product and will normally be used
for most products.

TABLE 4
Drawing Designation "A-4" Non-Critical

Standard dimensional tolerance table — Molded solid rubber products

Size (inches)

Fixed

Closure

Size (millimeters)

Fixed

Closure

Above Included

+/-

Above Included

+/-

0 - .40

.013

.032

0 - 10

.32

.80

.40 - .63

.0165

.036

10 - 16

.40

.90

.63 - 1.00

.020

.040

16 - 25

.50

1.00

1.00 - 1.60

.025

.045

25 - 40

.63

1.12

1.60 - 2.50

.032

.050

40 - 63

.80

1.25

2.50 - 4.00

.040

.056

63 - 100

1.00

1.40

4.00 - 6.30

.050

.063

100 - 160

1.25

1.60

6.30 & over
multiply fixed dimensional tolerances by 0.8%

160 & over
multiple fixed dimensional tolerances by 0.8%

Drawing Designation "A4" tolerances apply to products where dimensional control is non-critical
and secondary to cost.

All information above is from the RMA (Rubber Manufacturers Association, Inc.) Handbook.