General tolerances
Aluminium investment casting tolerances
| Dimension (inches) | Tolerance |
|---|---|
| Up to 0.500 | ± 0.004 |
| 0.500 to 1.000 | ± 0.006 |
| 1.000 to 1.500 | ± 0.008 |
| 1.500 to 2.000 | ± 0.010 |
| 2.000 to 2.500 | ± 0.012 |
| 2.500 to 3.500 | ± 0.015 |
| 3.500 to 5.000 | ± 0.018 |
| 5.000 to 7.500 | ± 0.021 |
| 7.500 to 10.000 | ± 0.024 |
| 10.000 to 12.500 | ± 0.027 |
| 12.500 to 15.000 | ± 0.030 |
| 15.000 to 18.000 | ± 0.035 |
| Dimension (mm) | Tolerance |
|---|---|
| Up to 12.0 | ± 0.10 |
| 12.0 to 25.0 | ± 0.15 |
| 25.0 to 37.0 | ± 0.20 |
| 37.0 to 50.0 | ± 0.25 |
| 50.0 to 62.0 | ± 0.30 |
| 62.0 to 87.0 | ± 0.38 |
| 87.0 to 125.0 | ± 0.46 |
| 125.0 to 187.0 | ± 0.53 |
| 187.0 to 250.0 | ± 0.61 |
| 250.0 to 312.0 | ± 0.69 |
| 312.0 to 375.0 | ± 0.76 |
| 375.0 to 460.0 | ± 0.90 |
Steel Investment casting tolerances
| Dimension (inches) | Tolerance |
|---|---|
| Up to 0.500 | ± 0.005 |
| 0.500 to 1.000 | ± 0.007 |
| 1.000 to 1.500 | ± 0.010 |
| 1.500 to 2.000 | ± 0.012 |
| 2.000 to 2.500 | ± 0.015 |
| 2.500 to 3.500 | ± 0.018 |
| 3.500 to 5.000 | ± 0.022 |
| 5.000 to 7.500 | ± 0.026 |
| 7.500 to 10.000 | ± 0.030 |
| 10.000 to 12.500 | ± 0.034 |
| 12.500 to 15.000 | ± 0.040 |
| 15.000 to 18.000 | ± 0.046 |
| Dimension (mm) | Tolerance |
|---|---|
| Up to 12.0 | ± 0.13 |
| 12.0 to 25.0 | ± 0.18 |
| 25.0 to 37.0 | ± 0.25 |
| 37.0 to 50.0 | ± 0.30 |
| 50.0 to 62.0 | ± 0.38 |
| 62.0 to 87.0 | ± 0.46 |
| 87.0 to 125.0 | ± 0.56 |
| 125.0 to 187.0 | ± 0.66 |
| 187.0 to 250.0 | ± 0.76 |
| 250.0 to 312.0 | ± 0.86 |
| 312.0 to 375.0 | ± 0.96 |
| 375.0 to 460.0 | ± 1.17 |
Investment casting wall thickness
Up to 75 Sq. Inches (500cm2) a tolerance of ± 0.008″ (± 0.2mm) applies.
Over 75 Sq. Inches (500cm2) a tolerance of ± 0.012″ (± 0.3mm) applies.
Investment casting using rapid prototypes
Investment casting tolerances as above do not apply when using rapid prototype waxes. Tolerances required are to be discussed and agreed.
Sand casting tolerance
| Dimension (inches) | Dimension (mm) |
|---|---|
| ± 0.02″ up to 6 inches, thereafter add 0.002″ per inch | ± 0.5 mm up to 150.0 mm, thereafter add 0.05 mm per 25.0 mm |
Sand casting wall thickness
The same sand casting tolerance as above applies to wall thicknesses. e.g. a 300mm long casting would have a tolerance of ± 0.8 applied to the wall thickness dimension.
(± 0.5 + (0.05 x 6) = ± 0.8)
Straightness / flatness tolerance
For investment castings a flatness tolerance of ± 0.004″ / inch (± 0.10 / 25mm) applies.
For sand castings the same principle as for sand cast wall thicknesses as above applies to flatness.
Draft angles
A draft angle of up to 1º will be applied to sand castings where necessary. This will add material to the casting unless otherwise indicated or agreed.
Angular tolerances
An angular tolerance of ± 0.5º will apply to investment castings. An angular tolerance of ± 1º will apply to sand castings.
Geometric tolerances
These are dependant on the casting configuration and tolerances required. They would need to be discussed at the quotation / order stage.
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