Casting Tolerances
Castings tolerances are dependent on both the materials cast and the method of production used. General Tolerances for metal alloy castings are specified by the International Standards Organisation, in their Standard ISO 8062 for SG Iron castings, made in machine produced sand moulds. The appropriate grades are Castings Tolerance (CT) 8 to 12. The capability of our green sand plants enable us to offer castings conforming to Grade CT8. Castings produced by hand will conform to grade CT9. These 2 grades are detailed in the table below:
Closer Tolerances may be offered in specific instances.
| Raw Casting Basic (mm) | Total Tolerance (mm) | ||
|---|---|---|---|
| Over | Up to and Including | CT8 | CT9 |
| 10 | 1.0 | 1.5 | |
| 10 | 16 | 1.1 | 1.6 |
| 16 | 25 | 1.2 | 1.7 |
| 25 | 40 | 1.3 | 1.8 |
| 40 | 63 | 1.4 | 2.0 |
| 63 | 100 | 1.6 | 2.2 |
| 100 | 160 | 1.8 | 2.5 |
| 160 | 250 | 2.0 | 2.8 |
| 250 | 400 | 2.2 | 3.2 |
| 400 | 630 | 2.6 | 3.6 |
| Mismatch (not to be added to values above) | 0.7 | 1.0 | |
Unless otherwise specified mismatch shall lie within the tolerance shown.
Unless otherwise specified the taper shall be added to the nominal dimension. It is not part of the tolerance.
