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)
and precision classes to define allowable deviations. A critical requirement is that a callout must include the grade and environmental conditioning (e.g., ISO 20457–TG6 + 23°C/50%RH ) to be enforceable. Super-Ingenuity Tolerance Categories (Materials) iso 20457 tolerance table pdf
The standard defines nine , ranging from TG1 (the most precise/tightest) to TG9 (the coarsest/widest). Officially introduced to replace the older German standard
: Reserved for specialized applications like medical devices or optical components requiring extreme accuracy. Class B (Medium Precision) the ISO 20457:2018 Standard provides engineers
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