Ensure your dimensional checks are specified at a defined measurement plane, as draft angles inherently alter the cross-sectional dimensions of a part along its depth.
Transitioning from metal design to plastic injection molding requires a shift in how you approach tolerances. Utilizing ISO 20457 ensures that your production team, mold maker, and quality control inspectors are operating under the same realistic, globally accepted baseline.
Before diving into the table itself, it is essential to understand the scope of the standard. is titled "Geometrical product specifications (GPS) — Classification of tolerances for dimensional and geometrical characteristics." iso 20457 tolerance table pdf
The PDF includes the exact formulas to calculate Volumetric Shrinkage Groups (VSG).
Unlike metal parts, plastic tolerances must account for processing shrinkage, tool binding, and material properties. Geometrical Tolerancing: Ensure your dimensional checks are specified at a
TG6 is a common baseline for thermoplastic injection molding. Below is a summary of the general tolerances for this group: Nominal Range (mm) Tool-Specific (W) (± mm) Non-Tool-Specific (NW) (± mm) 3 to 6 6 to 10 10 to 18 18 to 30 30 to 50 50 to 80 80 to 120 Source: Derived from OKW-Tolerances-en (PDF) . Tolerance Determination Process
The benchmark for high-accuracy engineering components, such as gear systems, automotive connectors, and medical enclosures. Before diving into the table itself, it is
Weeks turned into seasons. Ana hired Javier, a machinist who had learned his trade in a union shop before the plant closed; Mei, an apprentice fresh from technical college who brought CAD-model enthusiasm; and old Mr. Owens, who taught them to file by feel. Together they made parts that fit and moved with that quiet, satisfying precision the table described. They began to document their own variations, annotating the margins of a printed copy of ISO 20457 with notes about materials, surface finishes, and recurring machine workarounds. The table didn't become a dogma; it became a conversation.