| Standard | Material Focus | Key Feature | |----------|----------------|--------------| | ISO 20457 | Plastics (moulded) | PT grades, parting line allowances | | ISO 286 | Metals / machined | IT grades, very tight | | ISO 2768 (general tolerances) | Metals & plastics (vague) | Often too tight for plastics | | DIN 16901 | Old German standard for plastics | Replaced by ISO 20457 in 2020 |
For critical features, apply an individual tolerance using the table’s specific value. Understanding where ISO 20457 fits in the standards landscape helps justify its use to colleagues. iso 20457 tolerance table pdf
| PT Grade | Description | Typical Application | |----------|-------------|----------------------| | PT1 | Very fine (high precision) | Medical devices, optical components, precision gears | | PT2 | Fine | Consumer electronics, automotive interior trim | | PT3 | Medium | Standard housings, toys, general purpose parts | | PT4 | Coarse | Large panels, containers, parts with thin walls | | PT5 | Very coarse | Very large mouldings (>1000 mm) or warpage-prone materials | | PT6 | Extremely coarse (no tolerance specified) | Reference only for design verification | | PT7 | Up to agreement | For contract-specific requirements | | Standard | Material Focus | Key Feature
PT2 tolerance: ±0.30 mm
Compare this to ISO 286 for metal (IT7 grade for 100–200 mm: about ±0.035 mm). The plastic tolerance is nearly 10x wider. This illustrates the core lesson of ISO 20457: The plastic tolerance is nearly 10x wider
Enter – Plastics moulded parts – Tolerances and acceptance conditions . If you have been searching for the “iso 20457 tolerance table pdf” , you are likely facing the challenge of specifying realistic, cost-effective tolerances for injection-moulded components. This article provides a complete breakdown of the standard, explains how to interpret its tolerance tables, and guides you on obtaining and using the official PDF. What is ISO 20457? ISO 20457 is the first international standard dedicated exclusively to the dimensional tolerances of injection-moulded and compression-moulded plastic parts. Published in 2020, it replaces the outdated practice of applying metal-based tolerance systems (like ISO 286) to polymers.
In the world of plastics engineering and injection moulding, tolerances determine whether a part snaps together perfectly or fails catastrophically. For decades, engineers defaulted to the ISO 286 system for metal parts—only to find that plastics behave differently due to shrinkage, warpage, and creep.