Iso 20457 Tolerance Table Pdf //top\\ Online

To use the ISO 20457 system effectively, engineers typically follow these steps:

ISO 20457 categorizes tolerances into two distinct application groups based on whether the dimensions are tool-dependent or affected by post-molding assembly processes: 1. Series NW (Non-Tool-Dependent / Assembly Tolerances)

Let us extract a typical row from the ISO 20457 tolerance table (PT2 – fine grade for a dimension not affected by parting lines).

The global reference standard specifies the geometrical and dimensional tolerances and acceptance conditions for non-porous plastic molded parts. Officially introduced to replace the older German standard DIN 16742 , the ISO 20457:2018 Standard provides engineers, molders, and quality control professionals with a unified framework to manage the unique shrinkage, warpage, and thermal properties of molded polymers. Applying metal-machining tolerance standards like ISO 2768 directly to plastics often results in unachievable constraints and over-inflated production costs. Understanding the ISO 20457 Tolerance Groups

It applies specifically to , die castings, and similar processes. Unlike general machining tolerances, moulded parts have unique shrinkage, warpage, and draft angle requirements. iso 20457 tolerance table pdf

Many commercial standards retailers provide document previews showing the table of contents before purchase.

Overall part performance, fits, clearances, and functional interactions between separate molded pieces. 2. Series W (Tool-Dependent Tolerances)

standard (which replaced the older DIN 16901) provides a comprehensive system for determining manufacturing tolerances for plastic molded parts. It classifies tolerances into Tolerance Groups (TG)

: Parts naturally deform under minimal force compared to steel or aluminum. Structure of the ISO 20457 Tolerance Groups TOLERANCES To use the ISO 20457 system effectively, engineers

Angular tolerances are unique because the permissible deviation depends on the length of the shorter leg of the angle. The table provides deviations in degrees, minutes, or as a linear deviation per unit length (mm/m). A coarse tolerance for a 90° corner might permit ±1° for a very short leg, whereas the fine class could require ±0.5° or tighter.

The standard defines 10 Tolerance Groups, labeled .

For multi-component molded parts (e.g., overmolded or two-shot components), the tolerance grade must be determined for each material separately and specified as distinct general tolerances. For example, a hard component may be specified to TG5 while a soft component (elastomer) is specified to TG7.

The official ISO 20457 standard is a copyrighted document. Free, unauthorized copies should not be relied upon for professional engineering work. Legitimate sources for purchasing the ISO 20457:2018 PDF include: Officially introduced to replace the older German standard

Plastics absorb moisture and have a high coefficient of thermal expansion, causing parts to expand or contract based on ambient air conditions.

Preventing overly tight tolerances that increase tooling costs unnecessarily.

As the nominal size of the part increases, the allowable tolerance window expands to accommodate the higher volume of material shrinkage. Simplified Preview of an ISO 20457 Tolerance Table

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.