Mold-fixed vs non-mold-fixed
The single most important concept in DIN 16742. Every dimension on a moulded part is classified as either W (mold-fixed) or NW (non-mold-fixed). This classification determines which column of the tolerance table applies — and NW tolerances are always wider.
Dimension lies entirely within a single tool half. The feature is formed by one unbroken tool surface — no parting line, no moving element crosses it.
Examples: depth of a pocket, diameter of a boss, rib height, wall thickness measured within one half.
Dimension crosses the parting line, or involves a side action, core pull, or ejector pin. Depends on relative positioning of two or more tool components.
Examples: overall part height crossing parting line, hole diameter formed by two halves meeting, distance from a parting-line feature to a base surface.
For TG9 (the loosest tolerance group — flexible and very high-shrink materials), the W/NW distinction does not apply. A single tolerance value covers all dimensions regardless of mold geometry.
Size tolerances — symmetrical limit dimensions
Symmetrical ± tolerances for nominal dimensions of moulded part sizes. Values verified from the DIN 16742:2013 standard. TG4 only covers up to 120 mm — dimensions above this range require direct agreement with the mould maker. TG9 has no W/NW split.
| Nominal size (mm) | TG4 | TG5 | TG6 | TG7 | TG8 | TG9 (no W/NW) |
|||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| W | NW | W | NW | W | NW | W | NW | W | NW | ||
| 1–3 | ±0.03 | ±0.05 | ±0.05 | ±0.08 | ±0.07 | ±0.12 | ±0.13 | ±0.20 | ±0.20 | ±0.31 | ±0.30 |
| 3–6 | ±0.05 | ±0.08 | ±0.08 | ±0.11 | ±0.12 | ±0.18 | ±0.20 | ±0.29 | ±0.31 | ±0.45 | ±0.49 |
| 6–10 | ±0.06 | ±0.09 | ±0.09 | ±0.14 | ±0.14 | ±0.22 | ±0.24 | ±0.35 | ±0.38 | ±0.55 | ±0.75 |
| 10–18 | ±0.07 | ±0.11 | ±0.11 | ±0.17 | ±0.17 | ±0.26 | ±0.28 | ±0.42 | ±0.46 | ±0.65 | ±0.90 |
| 18–30 | ±0.08 | ±0.13 | ±0.13 | ±0.20 | ±0.20 | ±0.31 | ±0.34 | ±0.50 | ±0.55 | ±0.80 | ±1.05 |
| 30–50 | ±0.10 | ±0.15 | ±0.16 | ±0.23 | ±0.24 | ±0.37 | ±0.42 | ±0.60 | ±0.65 | ±0.95 | ±1.25 |
| 50–80 | ±0.12 | ±0.19 | ±0.19 | ±0.29 | ±0.29 | ±0.45 | ±0.50 | ±0.74 | ±0.80 | ±1.15 | ±1.50 |
| 80–120 | ±0.14 | ±0.22 | ±0.23 | ±0.35 | ±0.34 | ±0.53 | ±0.60 | ±0.88 | ±0.95 | ±1.40 | ±1.80 |
| 120–180 | — | — | ±0.27 | ±0.41 | ±0.40 | ±0.62 | ±0.70 | ±1.04 | ±1.10 | ±1.65 | ±2.10 |
| 180–250 | — | — | ±0.32 | ±0.48 | ±0.47 | ±0.73 | ±0.82 | ±1.22 | ±1.30 | ±1.95 | ±2.50 |
| 250–315 | — | — | ±0.37 | ±0.56 | ±0.54 | ±0.85 | ±0.95 | ±1.42 | ±1.50 | ±2.25 | ±3.00 |
| 315–400 | — | — | ±0.43 | ±0.65 | ±0.63 | ±0.98 | ±1.10 | ±1.65 | ±1.75 | ±2.62 | ±3.50 |
| 400–500 | — | — | ±0.49 | ±0.75 | ±0.73 | ±1.14 | ±1.28 | ±1.92 | ±2.04 | ±3.05 | ±4.10 |
W (mold-fixed): Use when the dimension lies entirely within one tool half. NW (non-mold-fixed): Use when the dimension crosses the parting line or involves a moving tool element. Always identify W vs NW before selecting a tolerance value — the difference is typically 40–60% wider for NW.
TG4 only covers up to 120 mm nominal size. Above 120 mm with TG4 requirements, tolerances must be agreed directly with the mould maker and are not covered by the standard.
Position tolerances — cylindrical tolerance zones
Position tolerances in DIN 16742 are specified as cylindrical tolerance zones (⌀, not ±). The DP nominal dimension is the distance from the toleranced feature to the origin of its reference system — not necessarily the nominal size of the feature itself. Position tolerances are never general tolerances; they must always be individually called out on the drawing.
DP is the longest distance from the toleranced element to the origin of the reference system used for that position tolerance. It is not the dimension of the feature — it is its distance from datum origin. A hole 80 mm from datum A uses the "80–120" row, not the hole's own diameter.
| DP nominal size (mm) | TG4 | TG5 | TG6 | TG7 | TG8 | TG9 | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| W | NW | W | NW | W | NW | W | NW | W | NW | ||
| 1–3 | ⌀0.08 | ⌀0.14 | ⌀0.14 | ⌀0.23 | ⌀0.20 | ⌀0.34 | ⌀0.37 | ⌀0.57 | ⌀0.57 | ⌀0.88 | ⌀0.85 |
| 3–6 | ⌀0.14 | ⌀0.23 | ⌀0.23 | ⌀0.31 | ⌀0.34 | ⌀0.51 | ⌀0.57 | ⌀0.82 | ⌀0.88 | ⌀1.3 | ⌀1.4 |
| 6–10 | ⌀0.23 | ⌀0.25 | ⌀0.31 | ⌀0.40 | ⌀0.51 | ⌀0.62 | ⌀0.82 | ⌀1.0 | ⌀1.3 | ⌀1.6 | ⌀2.1 |
| 10–18 | ⌀0.25 | ⌀0.31 | ⌀0.40 | ⌀0.48 | ⌀0.62 | ⌀0.74 | ⌀1.0 | ⌀1.2 | ⌀1.6 | ⌀1.8 | ⌀2.6 |
| 18–30 | ⌀0.31 | ⌀0.37 | ⌀0.48 | ⌀0.57 | ⌀0.74 | ⌀0.88 | ⌀1.2 | ⌀1.4 | ⌀1.8 | ⌀2.3 | ⌀3.0 |
| 30–50 | ⌀0.37 | ⌀0.42 | ⌀0.57 | ⌀0.65 | ⌀0.88 | ⌀1.1 | ⌀1.4 | ⌀1.7 | ⌀2.3 | ⌀2.7 | ⌀3.5 |
| 50–80 | ⌀0.42 | ⌀0.65 | ⌀0.65 | ⌀1.0 | ⌀1.1 | ⌀1.6 | ⌀1.7 | ⌀2.6 | ⌀2.7 | ⌀4.0 | ⌀4.2 |
| 80–120 | ⌀0.65 | ⌀0.90 | ⌀1.0 | ⌀1.4 | ⌀1.6 | ⌀2.3 | ⌀2.6 | ⌀3.5 | ⌀4.0 | ⌀5.7 | ⌀6.4 |
| 120–180 | — | — | ⌀1.6 | ⌀1.8 | ⌀2.6 | ⌀3.0 | ⌀4.0 | ⌀4.5 | ⌀6.5 | ⌀7.4 | ⌀9.0 |
| 180–250 | — | — | ⌀1.8 | ⌀2.0 | ⌀3.0 | ⌀3.3 | ⌀4.5 | ⌀5.0 | ⌀7.4 | ⌀8.0 | ⌀10.0 |
| 250–315 | — | — | ⌀2.0 | ⌀2.2 | ⌀3.3 | ⌀3.6 | ⌀5.0 | ⌀5.5 | ⌀8.0 | ⌀8.5 | ⌀11.5 |
Unlike size dimensions, position tolerances cannot be specified as general tolerances in the title block. Every position-toleranced feature must carry an individual feature control frame on the drawing. If a position requirement exists but is not individually called out, it is not controlled.
Tolerance group selection guide
TG selection in DIN 16742 is determined by a formal point-scoring system across five factors (P1–P5). The table below gives practical guidance for the most common applications.
| TG | Production class | Typical application | Process / cost note | Drawing callout |
|---|---|---|---|---|
| TG3 | Series 3–4 Special precision |
Micro-optical parts, precision medical implant housings, ultra-tight snap fits | Requires intensified process monitoring; always subject to supplier agreement; significant surcharge | DIN 16742–TG3 |
| TG4 | Series 2–3 Precise |
Sealing faces, bearing seats, precision inserts, connector interfaces, optical lens holders | Validated tool + process required; typically needs CMM per cavity; surcharge applies | DIN 16742–TG4 |
| TG5 | Series 2 Precise |
Functional mating surfaces, precise snap-fits, connector housings, fluid ports | Controlled production; process validation recommended; moderate surcharge | DIN 16742–TG5 |
| TG6 ★ | Series 1–2 Standard |
General enclosures, housings, covers, non-critical fits — default for most injection moulded parts | Standard production; no special measures required; most toolrooms work to this grade by default | DIN 16742–TG6 |
| TG7 | Series 1 Standard |
Non-functional features, internal structural ribs, semi-crystalline materials | Standard production; larger shrinkage or anisotropy expected | DIN 16742–TG7 |
| TG8 | Series 1 General |
Large cosmetic covers, non-mating visible surfaces, high-shrink materials | Warpage and anisotropic shrinkage expected; functional fixtures required for measurement | DIN 16742–TG8 |
| TG9 | Series 1 General |
Flexible/soft parts, rough structural mouldings, very high shrink materials (TPE, soft TPU) | No W/NW distinction; broad tolerances; functional fixturing essential | DIN 16742–TG9 |
Material family → typical TG range
DIN 16742 does not assign TG grades to specific materials — it uses a property-based point system. The table below gives practical starting points based on material shrinkage behaviour and stiffness. Always confirm with the mould maker for the specific grade and part geometry.
| Material / Family | Shrinkage (typical) | Typical TG (unfilled) | Typical TG (GF/CF filled) | Notes |
|---|---|---|---|---|
| Amorphous — low shrinkage, tightest tolerances possible | ||||
| PC — Polycarbonate | 0.5–0.7% | TG4–TG5 | TG3–TG4 | Low uniform shrinkage; very good dimensional stability; excellent for precision parts |
| ABS | 0.4–0.7% | TG4–TG5 | TG3–TG4 | Good baseline material for tight tolerances; widely used for housings and connectors |
| PC/ABS blend | 0.5–0.7% | TG5–TG6 | TG4–TG5 | Good toughness and stability; standard for automotive interior and electronics enclosures |
| PS — Polystyrene | 0.3–0.6% | TG4–TG5 | — | Very low shrinkage; brittle; rarely filled |
| PMMA — Acrylic | 0.2–0.6% | TG4–TG5 | — | Optical quality requires TG4; internal stresses can distort thin sections |
| Semi-crystalline — higher / anisotropic shrinkage, wider tolerances | ||||
| PA6 / PA66 — Nylon | 1.0–2.0% | TG5–TG6 | TG4–TG5 | Moisture absorption causes post-mould dimensional change; condition before measuring (48h 23°C/50%RH minimum) |
| POM — Acetal | 1.8–3.0% | TG6–TG7 | TG5–TG6 | High, relatively uniform shrinkage; good for gears and precision bearings when properly tooled |
| PP — Polypropylene | 1.5–2.5% | TG6–TG8 | TG5–TG7 | Significant anisotropic shrinkage; warpage common on large flat parts; use TG7–TG8 for large covers |
| PE — Polyethylene | 1.5–4.0% | TG7–TG9 | — | Very high and variable shrinkage; dimensional control difficult; TG9 typical for large structural parts |
| PPS — Polyphenylene sulfide | 0.5–1.5% | TG5–TG6 | TG4–TG5 | Semi-crystalline but low shrinkage when filled; good for precision automotive and electrical parts |
| High-performance engineering thermoplastics | ||||
| PEEK — Polyether ether ketone | 1.0–1.8% (unfilled) 0.4–0.9% (30% GF) |
TG5–TG6 | TG4–TG5 | High processing temperature (370–420°C melt); requires heated tool (160–200°C); unfilled shows moderate shrinkage anisotropy; GF-filled dramatically improves stability. Tight tolerances achievable but specialist moulder required. Confirm TG with moulder. |
| PEI — Polyetherimide (Ultem®) | 0.5–0.8% (unfilled) 0.2–0.5% (30% GF) |
TG4–TG5 | TG3–TG4 | Amorphous; low and uniform shrinkage; excellent for tight-tolerance medical and aerospace parts. High processing temperature (340–420°C); tool steel must be H13 or similar. GF-filled PEI approaches metal-like dimensional stability. Confirm TG with moulder. |
| Elastomers / flexible materials | ||||
| TPE / TPU | 0.5–3.0% | TG7–TG9 | — | Flexible; dimensional measurement requires functional fixtures; TG9 typical for soft grades |
DIN 16742 vs ISO 20457
Both standards replaced the old DIN 16901 and use the same TG1–TG9 system with very similar tolerance values. The choice between them is mostly about geographic context and supply chain convention.
| Topic | DIN 16742:2013 | ISO 20457:2018 |
|---|---|---|
| Scope | German national standard (DIN) | International standard (ISO) |
| Tolerance groups | TG1–TG9 | TG1–TG9 — same numbering and nearly identical values |
| Tolerance values | Essentially identical for TG5–TG9; minor rounding differences in TG3–TG4 | ISO 20457 TG4 is marginally tighter than DIN 16742 TG4 for small dimensions (<3 mm) — one fewer step up in ISO 286-1 grades |
| W/NW distinction | Yes — full W and NW columns throughout | Yes — same concept, same column structure |
| Acceptance conditions | Chapter 8 covers acceptance basics | More developed ABF (Acceptance Conditions for Moulded Part Production) system — includes conditioning, CMM vs fixture rules |
| DP dimension | Yes — same concept for position tolerances | Yes — explicitly defined with example (Annex G) |
| Material lists | Neither standard lists materials explicitly — both use property-based point scoring | Same — property-based; no fixed material-to-TG lookup table |
| Drawing callout | DIN 16742–TG6 |
ISO 20457–TG6 |
| When to use which | European / German supply chain; German Tier 1 suppliers; legacy German engineering drawings | International projects; non-European supply chains; new designs without geographic constraint |
For new designs without a specific supply chain constraint, ISO 20457 is the better choice — it is international and includes more developed inspection and acceptance rules. If you are working with European/German suppliers or on a drawing that already references DIN 16742, continue with DIN 16742. The tolerance values are effectively interchangeable for TG5–TG9.
Key rules for drawing application
| Rule | Detail |
|---|---|
| Drawing callout | State in title block or notes field: General tolerances DIN 16742–TG6. The TG number is mandatory — DIN 16742 alone is incomplete. |
| W vs NW identification | The designer must identify each dimension as W or NW. If not called out, the mould maker uses their judgment — this is a source of supplier disputes. Mark critical dimensions explicitly. |
| Position tolerances | Never general tolerances. Must be individually specified with a feature control frame. If not on the drawing, the position is not controlled. |
| Measurement conditioning | Parts must be conditioned before CMM measurement: 23°C ± 2K, 50% ± 10% RH, minimum 16h after demoulding (48h recommended for PA/PEEK/PEI). |
| Nominal size limits | Dimensions below 1 mm and above 1000 mm require direct agreement with the mould maker. General tolerances from the table do not apply automatically at these extremes. |
| TG3 and below | Always subject to mandatory agreement with the mould maker before specifying. TG3 and tighter require intensified process monitoring and often involve surcharges. |
| Material thickness | Tolerances for material (wall) thicknesses are subject to mandatory agreement — they are not automatically covered by Table 2. |
| PEEK / PEI measurement | High-performance materials processed at elevated tool temperatures may require extended conditioning periods (48–72h) before dimensional verification. Confirm conditioning protocol with moulder. |
How tolerance groups are assigned
DIN 16742 does not assign TG grades directly to named materials. Instead, Annex C defines a two-step process: first assign a tolerance series (1–4) based on production intent, then determine a column letter (A–F) based on material properties. The intersection gives the tolerance group.
| Tolerance series | Tolerance groups | |||||
|---|---|---|---|---|---|---|
| A | B | C | D | E | F | |
| Series 1 — Normal production | TG4 | TG5 | TG6 | TG7 | TG8 | TG9 |
| Series 2 — Accurate production | TG3 | TG4 | TG5 | TG6 | TG7 | TG8 |
| Series 3 — Precision production | TG2 | TG3 | TG4 | TG5 | TG6 | TG7 |
| Series 4 — Precision special production | TG1 | TG2 | TG3 | TG4 | TG5 | TG6 |
First select the tolerance series (1–4) based on your production intent — Series 1 is standard production with no special quality focus; Series 4 requires intensified process monitoring and always needs supplier agreement. Then determine the column letter (A–F) from the material classification rules below (Annex C.2–C.7). The cell at the intersection is the tolerance group to specify on the drawing.
Example: Standard production (Series 1) + unfilled ABS with VS under 0.5% → Column A → TG4. Same material in precision production (Series 3) → Column A → TG2.
C.2 — Amorphous thermoplastics (Tg > 60°C)
Includes: PS, SB, SAN, ABS, CA, CAB, CP, CAP, PVC-U, PVC-HI, ASA, PETam, PMMA, PMMA-HI, (ASA+PMMA), MABS, MBS, (PPE+SB), PC, (PC+ABS), (PC+ASA), PEI, PA6-3-T, COC, PESU, PSU, PPSU and others.
| Condition | → Column |
|---|---|
| Highest VS under 0.5% — shrinkage anisotropy possibly considered | A |
| Without filling/strengthening agents — no significant shrinkage anisotropy | |
| Calculated VS: at approx. ±10% is complied with | A |
| Calculated VS: not complied with | B |
| Distinct shrinkage anisotropy from filling/strengthening agents (e.g. fibre reinforcement) | |
| Anisotropy sufficiently considered in contour dimensioning | B |
| Anisotropy not considered | C |
C.3 — Semi-crystalline thermoplastics
Includes: PE, PP, PET, PBT, (PBT+PC), (PBT+ASA), PPS, PVDF, PCTFE, PFEP, ETFE, ECTFE, PFA, POM, PA6, PA6-HI, PA66, PA66-HI, PA6/66, PA6I, PA6/6T, (PA66+PPE), PA610, PA612, PA46, PA11, PA12, PAMD6, PEEK, PEK and others.
| Condition | → Column |
|---|---|
| Highest VS under 0.5% — shrinkage anisotropy possibly considered | A |
| Unfilled — Modulus of elasticity over 1 200 N/mm² | |
| Calculated VS under 1% | B |
| Calculated VS 1% to 2% | C |
| Calculated VS over 2% | D |
| Unfilled — Modulus of elasticity under 1 200 N/mm² | |
| Calculated VS under 1% | C |
| Calculated VS 1% to 2% | D |
| Calculated VS over 2% | E |
| With filling and strengthening agents | |
| Without noteworthy shrinkage anisotropy, or with its consideration for contour dimensioning | B |
| Without consideration of the shrinkage anisotropy for contour dimensioning | C |
C.4 — Soft-elastic thermoplastics / TPE (no fillers)
Includes: PVC-P, PA12-P, EVAC, TPS-SEBS, TPS-SBS, TPO-(EPDM+PP), TPO-(EVAC+PVDC), TPV-(EPDM-X+PP), TPC, (TPC+PBT), TPU, TPA and others. Column assignment via curing classification (Table C.2 — Shore D/A hardness) — see below.
| Shore hardness | Class I (VS < 1.5% or anisotropy compensated) | Class II (VS > 1.5% with uncompensated anisotropy) |
|---|---|---|
| Shore D > 35 | C | D |
| Shore A 50–90 | D | E |
| Shore A < 50 | E | F |
C.5 — Liquid crystalline polymers (LCP)
Distinct shrinkage anisotropy is often unavoidable at low overall shrinkage due to flow orientation of rigid molecules. Fillers tend to reduce this anisotropy.
| Condition | → Column |
|---|---|
| Highest VS under 0.5% | A |
| Shrinkage anisotropy effect can be adequately compensated (part/tool design + process) | A |
| Shrinkage anisotropy effect cannot be compensated | B |
C.7 — Thermoset moulding compounds
Includes: PF, UF, MF, MPF, UP, EP, PDAP, PUR-X, SI-X and others.
| Condition | Injection / Injection-compression / Transfer moulding | Compression moulding |
|---|---|---|
| Highest VS under 0.5% | A | B |
| Anticipated shrinkage distribution vs calculated VS — with consideration of shrinkage anisotropy | ||
| approx. ±10% | A | B |
| approx. ±20% | B | C |
| ≥ ±30% | C | D |
Worked examples — PEEK & PEI
PEEK is semi-crystalline → use Annex C.3. Modulus of elasticity typically 3 600–4 800 N/mm² (well over 1 200). Typical moulding shrinkage unfilled: 1.0–1.8%.
VS 1%–2%, modulus >1 200 N/mm² → Column C
Series 1 + Column C → TG6
GF30-filled PEEK: shrinkage ~0.4–0.9%, anisotropy considered → Column B → TG5
PEI is amorphous → use Annex C.2. Typical moulding shrinkage: 0.5–0.8%. Modulus ~3 300 N/mm².
VS at approx. ±10% complied with → Column A
Series 1 + Column A → TG4
GF30-filled PEI: shrinkage anisotropy with consideration → Column B → TG5. Anisotropy not considered → Column C → TG6
Tolerance Series 3 and 4 are always subject to mandatory agreement between the customer and mould maker before specifying on a drawing. Only functionally critical dimensions justify the production cost of Series 3–4, which require significant surcharges and process intensification.