Linear Tolerances for Cast Dimensions:
Lowest-to-Highest Quality & Cost-Inches (mm)
Dimension |
Lowest (±) |
Medium (±) |
Highest (±) |
Inch/ mm |
Inch/ mm |
Inch/ mm |
Inch/ mm |
＜0.25/ 6 |
0.010/ 0.25 |
0.005/ 0.13 |
0.0025/ 0.06 |
＜0.50/ 12 |
0.010/ 0.25 |
0.0015/ 0.13 |
0.0025/ 0.06 |
＜1/ 25 |
0.010/ 0.25 |
0.005/ 0.13 |
0.005/ 0.13 |
＜2/ 50 |
0.013/ 0.33 |
0.010/ 0.25 |
0.008/ 0.20 |
＜3/ 76 |
0.016/ 0.41 |
0.015/ 0.38 |
0.010/ 0.25 |
＜4/ 101 |
0.019/ 0.49 |
0.017/ 0.44 |
0.012/ 0.30 |
＜5/ 127 |
0.022/ 0.56 |
0.020/ 0.51 |
0.013/ 0.34 |
＜6/ 152 |
0.25/ 0.63 |
0.022/ 0.56 |
0.015/ 0.38 |
＜7/ 178 |
0.028/ 0.72 |
0.025/ 0.63 |
0.017/ 0.42 |
＜8/ 203 |
0.031/ 0.079 |
0.028/ 0.72 |
0.018/ 0.46 |
＜9/ 229 |
0.034/ 0.87 |
0.030/ 0.77 |
0.020/ 0.50 |
＜10/ 254 |
0.037/ 0.95 |
0.032/ 0.82 |
0.021/ 0.52 |
＞10/ 254 |
0.005/ 0.13 |
0.004/ 0.10 |
0.003/ 0.08 |
FLATNESS:
Flatness refers to single plane surface and is usually a function of volumetric shrinkage.
| U.S. |
| Thickness
|
Dish per 6 sq. inches of surface |
Dish per 42 sq. cm of surface
|
Inch/mm |
Inch |
mm |
＜0.250/ ＜6.5mm |
Insignificant |
Insignificant |
0.25-0.5/ 6.5mm-13mm |
0.004 in. TIR |
0.102 mm TIR |
0.51-1.000/ 13mm-25mm |
0.008 in. TIR |
0.201 mm TIR |
1.001-2.000/ 25mm-50mm |
0.016 in. TIR |
0.406 mm TIR |
STRAIGHTNESS:
Tolerance for axial straightness: ±.005 in. per inch (±.127mm per 25mm) as cast.
CONCENTRICITY:
1.Centers is concentric within .005 in. per inch (±.127mm per 25mm) of maximum separation with concentricity of diameters in a
shaft is also a function of straightness.
2.This disregards out-of-roundness and assumes the measurements in the same plane while the concentricity is being measured in
separate planes, the requirements of paragraph 1 above must be added. Center of I.D. to O.D. will be concentric within .003 in.
per 1/2 in. (.076mm per 13mm) of wall thickness.
ROUNDNESS- SOLID BARS:
A general rule of ±.005 in. per inch (.127mm per 25mm) may be applied. Roundness is a function of normal shrinkage variations in the metal. Shrinkage variation increases with diameter and the tolerance required increases proportionately.
ANGLES:
As-cast tolerances of angles depend on the casting’s location. They range from ±1/2° for well supported positions to ±2° where interior to become deformed could be expected. To minimize distortion of the inclusion of gussets and ribs and many sections can be mechanically straightened.
HOLES POSITIONING:
±.005 in. per inch (.127mm per 25mm) from any single reference point.
BLIND HOLES:
Blind holes are possible if length is under diameter parameters. As for nonferrous materials, blind holes under 2 in. (6.5mm) could be achieved if length is controlled under twice the diameter.
PARALLEL SECTIONS:
Specific tolerance range for all combinations will not be achieved if controlling relationship of length and width of elements are not examined carefully. However, general tolerance of .010 in. TIR per inch (.254mm per 25mm) could be applicable.
|
