When designing a plastic part, the question of dimensional tolerances is essential. It directly impacts the final quality, production costs, and even technical feasibility. To make the right choice, you should rely on the NF T 58-000 standard.
What is the NF T 58-000 standard?
It is a French reference standard in the plastics industry, used to define acceptable dimensional tolerances for injected plastic parts. It considers three major factors:
The 3 Tolerance Classes Defined by the NF T 58-000 Standard:
Tolerance Class | Description | Advantages | Drawbacks | Recommended Use |
|---|---|---|---|---|
Standard | Production with standard machines and tooling | Balance between cost and precision | Average tolerances | Default choice, unless otherwise specified |
Reduced | Specific tooling + improved in-process control | Improved precision | Higher cost (tooling and production) | For parts with critical dimensional requirements |
Precision | Highly specialized machines and tooling | Very high dimensional precision | Very high cost, not offered by all manufacturers | Rare, only for very specific and demanding applications |
Dimensional tolerance categories by material :
Symbol | Material | Dimensional tolerance category |
|---|---|---|
PA | Unfilled polyamides PA6, PA66, PA6/10, PA11, PA12 Filled and unfilled amorphous polyamides Filled PA6, PA66, PA6/10, PA11, PA12 | 3 4 4 |
POM | Polyoxymethylene Filled polyoxymethylene | 3 4 |
PBT | Unfilled poly(butylene terephthalate) Filled PBT | 3 4 |
PET | Crystalline poly (ethylene terephthalate) Amorphous poly (ethylene terephthalate) Filled poly (ethylene terephthalate) | 3 4 4 |
PP | Filled polypropylene Unfilled PP/EPDM modified polypropylene | 3 3 |
PPE | Unmodified poly(phenylene ether) Unfilled modified poly(phenylene ether) Glass fiber reinforced modified poly(phenylene ether) | 4 4 4 |
PC | Filled and unfilled polycarbonate | 4 |
ABS | Filled and unfilled poly(acrylonitrile/butadiene/styrene) | 4 |
PF | Phenolic plastics PF2 C3 Phenolic plastics PF2 A1, PF2 D1, PF2 D3, PF3 D4 | 1 2 |
UP | Unsaturated polyesters (moulding compositions) Preimpregnated (unsaturated polyesters) | 1 2 |
EP | Epoxydes | 1 |
PDAP | Poly(diallyl-phthalates) (with organic fillers) | 1 |
MF | Melamines-formaldehyde with mineral filler Melamines-formaldehyde with organic or mixed filler | 1 2 |
PS | Filled polystyrenes Unfilled polystyrenes | 4 4 |
S/B | Poly(styrene/butadiene) | 4 |
SAN | Filled and unfilled poly(styrene/acrylonitrile) | 4 |
PMMA | Poly(methylmethacrylate) | 4 |
PUR | Thermoplastic polyurethanes Shore hardness > 50 Thermoplastic polyurethanes Shore hardness ≤ 50 (1) | 3 5 |
PVC-U | Unplasticised poly(vinyl chloride) | 4 |
PSU | Filled or unfilled polysulfone | 4 |
PPS | Reinforced poly(phenylene sulphide) | 4 |
PES | Unfilled poly(ethersulfone) | 4 |
PE | Unfilled polyethylenes | 5 |
PP | Filled polypropylenes | 5 |
PVC-P | Plasticised poly(vinyl chloride) Shore D hardness > 50 (1) Plasticised poly(vinyl chloride) Shore D hardness ≤ 50 (1) | 3 5 |
FEP | Perfluoride poly(ethylene/propylene) | 5 |
Note :
Special case: SEBS (thermoplastic elastomers):
Category 4
Category 5
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