Iso 20457 Tolerance Table Pdf Site

Do you have any that require high precision? Share public link

For engineers, quality managers, and procurement professionals working with injection-molded plastic parts, precision is everything. However, the properties of plastics—from material shrinkage to thermal expansion—make them fundamentally different from machined metals. Applying metal tolerances to plastic parts inevitably leads to costly rework, rejected shipments, and strained supplier relationships. This is where comes into play.

Unlike metals, plastic dimensions are highly dynamic. ISO 20457 determines tolerance groups based on four major variables:

Standard manufacturing conditions with typical tooling costs. iso 20457 tolerance table pdf

One of the distinctive features of ISO 20457 is its use of surface profile tolerance within a specified datum system. This approach allows for comprehensive control over the entire surface form of the molded part, rather than piecemeal control of individual features. General tolerances are applied with surface profile tolerance linked to a defined datum reference frame, ensuring consistency across all integral features.

A company is designing a mounting bracket for an electric motor. The bracket is a sheet metal part (2mm thick, 200mm long). The motor has a shaft that aligns to a hole.

A typical tolerance table in this standard will include: Do you have any that require high precision

To standardize expectations between designers and molders, the International Organization for Standardization introduced . This standard replaces the older DIN 16742 standard and provides a robust framework for determining geometric tolerances and deviations.

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"We sell trust," Mei said. "We sell parts that keep someone's machine running." Javier nodded; Mr. Owens thumped the bench with a palm. They decided to hold the line. Instead of racing to the bottom on price, they focused on value: traceability, documentation, faster turnaround, and the small but critical assembly testing they insisted on. They printed the tolerance table into their job sheets, used it to teach clients why a tighter fit mattered for longevity, and even offered tolerance-driven design advice to engineers who were used to outsourcing without oversight. Applying metal tolerances to plastic parts inevitably leads

Failing to account for material shrinkage leads to unrealistic tolerances. A tolerance that is achievable in ABS (low shrinkage) may be impossible in unfilled nylon (high shrinkage). Always reference the appropriate shrinkage group when specifying tolerances.

The tolerance tables within ISO 20457 offer engineers a reliable reference for specifying achievable tolerances based on nominal dimension ranges, tolerance grades, and dimension types. When applied correctly—with clear specification of TG grades, acceptance conditions, and W/NW classifications—ISO 20457 reduces costly disputes between designers, mold makers, and quality inspectors.