|
U.S.
|
|
METRIC
|
| Up to 1.000 in. |
±.010 in. |
|
Up to 25 mm |
±.254 mm |
| Up to 2.000 in. |
±.015 in. |
|
Up to 50 mm |
±.381 mm |
| Up to 3.000 in. |
±.020 in. |
|
Up to 75 mm |
±.508 mm |
| Up to 4.000 in. |
±.025 in. |
|
Up to 100 mm |
±.635mm |
| Up to 5.000 in. |
±.030 in. |
|
Up to 125 mm |
±.762 mm |
| Up to 6.000 in. |
±.035 in. |
|
Up to 150 mm |
±.889 mm |
FLATNESS
Flatness refers to single plane surface and is usually a function of volumetric shrinkage.
|
U.S.
|
|
METRIC
|
|
Thickness
|
Dish per 6 sq. inches of surface
|
Thickness
|
Dish per 42 sq. cm of surface
|
|
Up to .250 in.
|
insignificant
|
Up to 6.5 mm
|
insignificant
|
|
.251 in. to .500 in.
|
.004 in. TIR
|
6.5 mm to 13 mm
|
.102 mm TIR
|
|
.501 in. to 1.000 in.
|
.008 in. TIR
|
13 mm to 25 mm
|
.201 mm TIR
|
|
1.001 in. to 2.000 in.
|
.016 in. TIR
|
25 mm to 50 mm
|
.406 mm TIR
|
STRAIGHTNESS
Tolerances for axial straightness: ±.005 in. per inch (±.127 mm per 25 mm) as cast.
CONCENTRICITY
-
Concentricity of diameters in a shaft is also a function of straightness. Centers will be concentric within .005 in. per inch (±.127 mm per 25 mm) of maximum separation.
-
Centers of I.D. to O.D. will be concentric within .003 in. per 1/2 in. (.076 mm per 13 mm) of wall thickness. This disregards out-of-roundness, and assumes measurements in the same plane If the concentricity is being measured in separate planes, the requirements of paragraph 1 above must be added.
SURFACE FINISH
|
Metal
|
MICRO-INCHES
Average RMS value
|
|
MICRO-METERS
Average Ra value
|
|
Aluminum
|
60-100
|
1.50-2.50
|
|
Beryllium Copper
|
60-100
|
1.50-2.50
|
|
Cobalt Chrome
|
80-100
|
2.00-2.50
|
|
300 Series Stainless
|
90-125
|
2.25-3.20
|
|
Carbon Steel
|
90-125
|
2.25-3.20
|
|
400 Series Stainless
|
100-125
|
2.50-3.20
|
ROUNDNESS-SOLID BARS
Roundness is a function of normal shrinkage variations in the metal. Shrinkage variation increases with diameter and the tolerance required increases proportionately. A general rule of ±.005 in. per inch (.127 mm per 25 mm) may be applied.
ANGLES
As-cast tolerances of angles depend on their location in casting. They range from ± 1/2° for well supported positions to ± 2° where inherent distortion could be expected. Inclusion of gussets and ribs often minimizes distortion and many sections can be mechanically straightened.
HOLE POSITIONING
±.005 in. per inch (.127 mm per 25 mm) from any single reference point.
BLIND HOLES
Blind holes can be cast if length does not exceed the diameter. In nonferrous materials, blind holes under 2 in. (6.5 mm) may be cast if length does not exceed twice the diameter.
PARALLEL SECTIONS
Controlling relationship is between length and width of the elements being checked. To establish a specific tolerance range for all combinations would be impossible, but a general tolerance of .010 in. TIR per inch (.254 mm per 25 mm) may be used.
WALL THICKNESS
|
|
U.S.
MINIMUM WALL
|
|
METRIC
MINIMUM WALL
|
|
Metal
|
Small Area
|
Normal
|
Small Area
|
Normal
|
|
Beryllium Copper
|
.035 in.
|
.050 in.
|
.899 mm
|
1.270 mm
|
|
Ductile Iron
|
.035 in.
|
.050 in.
|
.899 mm
|
1.270 mm
|
|
Aluminum
|
.040 in.
|
.060 in.
|
1.016 mm
|
1.524 mm
|
|
300 Series Stainless
|
.040 in.
|
.060 in.
|
1.016 mm
|
1.524 mm
|
|
Cobalt Chrome
|
.040 in.
|
.060 in.
|
1.016 mm
|
1.524 mm
|
|
400 Series Stainless
|
.045 in.
|
.070 in.
|
1.143 mm
|
1.778 mm
|
|
Carbon Steel
|
.050 in.
|
.080 in.
|
1.270 mm
|
2.032 mm
|
ROUNDNESS-HOLLOW TUBING
As-cast tolerances are ± .005" per inch (± .127 mm per 25 mm). Tubular section out-of-roundness may be altered mechanically according to wall thickness and ductility. Tolerances are as follows:
|
U.S.
|
|
METRIC
|
|
Diameter
|
Tolerances
|
Diameter
|
Tolerances
|
|
Up to 1 in.
|
.006 in. TIR
|
Up to 25 mm
|
.152 mm TIR
|
|
1 in. to 1 1/2 in.
|
.008 in. TIR
|
25 mm to 37.5 mm
|
.203 mm TIR
|
|
1 1/2 in. to 2 in.
|
.010 in. TIR
|
37.5 mm to 50 mm
|
.254 mm TIR
|
|
2 in. to 3 in.
|
.015 in. TIR
|
50 mm to 75 mm
|
.381 mm TIR
|
STANDARD CASTING TOLERANCES