1. Standard Overview
| Standard | Scope | Tolerance System | Investment Casting Application |
|---|---|---|---|
| ISO 8062-3:2023 | Global casting tolerance standard | CT1–CT16 (lower = tighter) | Silica sol: CT4–CT6 Water glass: CT7–CT8 |
| GB/T 6414-2017 | Chinese standard (identical to ISO 8062) | Same CT grades | Domestic customers |
| VDG P690 | German standard for lost‑wax casting | D1, D2, D3 | European / German OEMs |
2. Linear Tolerance Comparison (±mm)
| Size Range (mm) | VDG P690 D1 | VDG P690 D2 | VDG P690 D3 | ISO CT5 | ISO CT6 | ISO CT7 |
|---|---|---|---|---|---|---|
| 0–6 | ±0.10 | ±0.08 | ±0.06 | ±0.18 | ±0.26 | ±0.37 |
| 6–10 | ±0.12 | ±0.10 | — | ±0.19 | ±0.27 | ±0.39 |
| 10–14 | ±0.15 | ±0.12 | ±0.09 | ±0.19 | ±0.27 | ±0.39 |
| 14–18 | ±0.20 | ±0.14 | ±0.09 | ±0.21 | ±0.29 | ±0.44 |
| 18–24 | ±0.25 | ±0.17 | ±0.12 | ±0.21 | ±0.29 | ±0.44 |
| 24–30 | ±0.30 | ±0.20 | ±0.14 | ±0.23 | ±0.32 | ±0.45 |
| 30–40 | ±0.37 | ±0.25 | ±0.17 | ±0.23 | ±0.32 | ±0.45 |
| 40–50 | ±0.44 | ±0.30 | ±0.20 | ±0.25 | ±0.35 | ±0.50 |
| 50–65 | ±0.52 | ±0.38 | ±0.23 | ±0.28 | ±0.39 | ±0.55 |
| 65–80 | ±0.60 | ±0.46 | ±0.27 | ±0.28 | ±0.39 | ±0.55 |
| 80–100 | ±0.68 | ±0.53 | ±0.30 | ±0.31 | ±0.44 | ±0.60 |
| 100–120 | ±0.76 | ±0.60 | ±0.33 | ±0.31 | ±0.44 | ±0.60 |
| 120–140 | ±0.84 | ±0.65 | ±0.36 | ±0.35 | ±0.50 | ±0.70 |
| 140–160 | ±0.92 | ±0.72 | ±0.38 | ±0.35 | ±0.50 | ±0.70 |
| 160–180 | ±1.02 | ±0.80 | ±0.42 | ±0.35 | ±0.50 | ±0.70 |
| 180–200 | ±1.12 | ±0.88 | ±0.43 | ±0.35 | ±0.50 | ±0.70 |
| 200–225 | ±1.28 | ±0.95 | ±0.47 | ±0.35 | ±0.50 | ±0.70 |
| 225–250 | ±1.44 | ±1.05 | ±0.51 | ±0.35 | ±0.50 | ±0.70 |
3. Tolerance Correlation
- VDG P690 D2 ≈ ISO 8062 CT5 (Standard silica sol investment casting)
- VDG P690 D3 ≈ ISO 8062 CT4 (Premium precision casting)
- VDG P690 D1 ≈ Between CT5 and CT6
4. Application Notes
- D1 / CT6: General dimensions, non-critical surfaces, machined areas
- D2 / CT5: Critical unmachined surfaces, assembly features (most common)
- D3 / CT4: High-precision requirements, special process control needed
