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.
For general thermoplastics, the standard typically defaults to unless otherwise specified.
The International Organization for Standardization established (which superseded the older DIN 16742 standard) to create a unified global framework for tolerancing molded plastic parts. What is ISO 20457?
for accurate calculations.
Before ISO 20457, many European-influenced toolmakers referenced , which defines tolerance groups based on part size and material shrinkage category. DIN 16901 classifies tolerances into Series 1 (Normal), Series 2 (Fine), and Series 3 (Precision). ISO 20457 expands this framework with nine tolerance grades (TG1–TG9), compared with the six tolerance groups in DIN 16901, providing greater granularity and international consistency.
In mold design, the tolerance of mold molding dimensions should be controlled at . Precision molds adopt a smaller proportion (e.g., 1/5) to reserve margins for shrinkage fluctuation, mold wear, and process changes.
Note: This table represents general dimensional tolerances. For exact allocations based on specific compound shrinkage rates and tool-bound vs. non-tool-bound dimensions, please reference the official ISO 20457 PDF framework. 5. Tool-Bound vs. Non-Tool-Bound Dimensions iso 20457 tolerance table pdf
, which leads to unnecessarily expensive molds and high scrap rates.
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.
Plastics shrink as they cool. Amorphous materials (like Polycarbonate) shrink evenly, while semi-crystalline materials (like Polypropylene) or glass-filled polymers shrink unevenly (anisotropy). ISO 20457 classifies materials into specific groups based on their processing shrinkage variance. 2. Evaluation Level (Production Accuracy) One of the distinctive features of ISO 20457
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.
based on material properties (such as shrinkage and stiffness) and the manufacturing process used. www.makrolar.eu Tolerance Tables Overview
The standard defines nine , ranging from TG1 (the most precise/tightest) to TG9 (the coarsest/widest). for accurate calculations
The standard is part of the broader ISO GPS (Geometrical Product Specifications) system. The GPS "matrix model" provides a set of rules and tools for the specification of geometry, and ISO 20457 is fully integrated within this framework.