Lookup
Method, assumptions and limitations
Direct table lookup of the linear dimensional casting tolerance (DCT) for the size range containing the nominal dimension, per ISO 8062-3 (edition 2023). No interpolation is performed. The tool covers grades DCTG 4 to 8 up to 400 mm; it does not cover wall thicknesses (for which the standard applies a coarser grade), geometrical tolerances, VDG P 690 accuracy grades or any supplier capability. Which grade is achievable for a given feature must be agreed with the foundry.
Reference table
| Nominal dimension (mm) | DCTG 4 | DCTG 5 | DCTG 6 | DCTG 7 | DCTG 8 |
|---|---|---|---|---|---|
| > 0 – 10 | 0.26 | 0.36 | 0.52 | 0.74 | 1.00 |
| > 10 – 16 | 0.28 | 0.38 | 0.54 | 0.78 | 1.10 |
| > 16 – 25 | 0.30 | 0.42 | 0.58 | 0.82 | 1.20 |
| > 25 – 40 | 0.32 | 0.46 | 0.64 | 0.90 | 1.30 |
| > 40 – 63 | 0.36 | 0.50 | 0.70 | 1.00 | 1.40 |
| > 63 – 100 | 0.40 | 0.56 | 0.78 | 1.10 | 1.60 |
| > 100 – 160 | 0.44 | 0.62 | 0.88 | 1.20 | 1.80 |
| > 160 – 250 | 0.50 | 0.70 | 1.00 | 1.40 | 2.00 |
| > 250 – 400 | 0.56 | 0.78 | 1.10 | 1.60 | 2.20 |
Total linear dimensional casting tolerance (DCT) in mm for grades DCTG 4 to 8 and nominal dimensions up to 400 mm, as tabulated in ISO 8062-3. The tolerance zone is normally placed symmetrically about the nominal dimension. Extract for orientation; the standard itself is authoritative and contains further grades, sizes, wall-thickness rules and geometrical tolerances.
Which grade?
The achievable grade depends on the alloy, the size and geometry of the part, whether the dimension is restrained by the shell, and the production quantity. For investment castings, grades around DCTG 4 to 6 are commonly quoted for general dimensions. A finer grade for selected dimensions is possible by agreement and usually requires die correction after first samples. The background is explained on the tolerances page.