One rainy afternoon, a designer named Lila walked into the shop carrying a folded drawing of a new agricultural pump. Her company had outsourced molds for the past decade, but their latest prototype leaked at the coupling because of an overlooked tolerance. She had been told: come here; these folks care about fit. Ana read the drawing, checked the table, and proposed a blend of interference fit on the drive and a running fit on the bearing bore, with a specified surface finish to keep oil film intact. Lila watched as the team translated abstract values into toolpaths, cutters, and test assemblies.
Example of a simplified tolerance structure (Not a complete table): Dimension (mm) TG3 (Tight) TG6 (Standard) TG7 (Loose) 30 - 100
Do not apply tight tolerances to the whole part. Mark functional fitment areas with specific limits, and let non-critical housings fall back on general TG6 or TG7 rules.
: A comprehensive 28-page PDF that includes detailed tolerance tables, explanations of dimensional deviations, and the relationship between ISO 20457 and DIN 16742. iso 20457 tolerance table pdf
ISO 20457 is the first international standard dedicated exclusively to the dimensional tolerances of injection-moulded and compression-moulded plastic parts. Published in 2020, it replaces the outdated practice of applying metal-based tolerance systems (like ISO 286) to polymers.
Classifies materials based on their shrinkage behavior (e.g., crystalline, amorphous, reinforced).
The standard uses two main tables to determine the applicable tolerance: INTERNATIONAL STANDARD ISO 20457 One rainy afternoon, a designer named Lila walked
(and its German equivalent DIN ISO 20457 ) is the primary international standard for specifying manufacturing tolerances of plastic molded parts
The most sought-after part of the standard is its tolerance table. This table defines the achievable dimensional tolerances for a plastic part based on a few critical parameters:
Tolerances that are too strict (e.g., trying to achieve TG3 on a complex, amorphous plastic part) can dramatically increase manufacturing costs by requiring more precise, expensive tooling and longer cycle times. Ana read the drawing, checked the table, and
In the world of mechanical engineering and precision manufacturing, standards are the bedrock of quality. Among the myriad of ISO standards, plays a specific and vital role in ensuring that complex machinery operates smoothly and reliably. For engineers and procurement officers, accessing the ISO 20457 tolerance table PDF is often a critical step in the design and verification process.
If tolerances are too loose, parts may not fit or perform as designed.