ISO 20457 , which replaced older standards like DIN 16901 and DIN 16742, defines the geometrical and dimensional tolerances for plastic molded parts. Unlike metal machining, plastic molding must account for unique variables such as material shrinkage, thermal expansion, and moisture absorption. Understanding the TG5 Classification
You cannot simply choose TG5 on a drawing without evaluating the underlying material and process physics. ISO 20457 relies on a matrix that matches the material's with the desired tolerance group. 1. Material Shrinkage Behavior
As global regulations tighten (e.g., the EU’s PPWR - Packaging and Packaging Waste Regulation), demand for high-quality recyclates has skyrocketed. However, the market is flooded with "recycled grades" that fail during injection molding due to poor filler dispersion or fiber breakage. Iso 20457 Tg5
Require wider tolerances due to tool shift, clamping variations, and mechanical play. Practical Application: Calculating TG5 Tolerances
A small functional feature of might require a tight tolerance window of roughly ±0.08 mm . ISO 20457 , which replaced older standards like
The standard classifies dimensional limits into nine distinct Tolerance Groups (from TG1 to TG9).
: The definitive threshold for accurate technical production involving advanced engineering polymers. ISO 20457 relies on a matrix that matches
Highly restricted previews of the standard's scope and terms are available on the ISO Online Browsing Platform (OBP) . Understanding TG5 in ISO 20457
Extreme precision (high cost, specialized tooling). TG4: High-precision components like gears and small wheels.
This article provides a comprehensive overview of the standard, detailing what TG5 entails, how to apply it, and how it compares to other manufacturing tolerances.