Ranging from TG1 (tightest) to TG7 (loosest).
Choosing the right TG depends on the material's shrinkage behavior and the part's functional requirements.
for part sizes based on manufacturing effort and tooling.
). For the definitive, legally binding matrix, always consult the official ISO 20457 PDF documentation. Nominal Dimension (mm) 3 to 6 6 to 10 10 to 18 18 to 30 30 to 50 50 to 80 80 to 120 120 to 180 180 to 250 Factors Influencing Plastic Molded Tolerances iso 20457 tolerance table pdf
The machinist reads the PDF, applies the correct deviations, and the bracket is cheap to produce (not over-toleranced) but still fits the motor.
The standard provides tolerance tables categorized by the and the Material Group .
Understanding ISO 20457: The Definitive Guide to Plastic Molded Part Tolerances Ranging from TG1 (tightest) to TG7 (loosest)
High-shrinkage raw polymers or flexible elastomeric components. The Structure of the ISO 20457 Tolerance Table
ISO 20457 is a critical reference for the pump industry, bridging the gap between design theory and physical reality. The tolerance tables contained within the standard are essential tools for ensuring the reliability, efficiency, and safety of pumping systems. While accessing the official PDF requires adherence to copyright protocols, the value it provides in reducing downtime and ensuring part compatibility is an investment that pays for itself in operational efficiency.
Understanding where ISO 20457 fits in the standards landscape helps justify its use to colleagues. The standard provides tolerance tables categorized by the
Unlike metal standards, ISO 20457 accounts for the molding compound properties and how they shrink during cooling.
Having the PDF is useless without interpretation. Here is a step-by-step guide to using the in real-world engineering.