Amorphous plastics (e.g., ABS, PC) generally exhibit lower and more predictable shrinkage than semi-crystalline plastics (e.g., POM, PA66).
The tolerance applied to a part depends on both the chosen and the Nominal Dimension (the size of the feature). Nominal Dimension (mm) TG4 (High Precision) TG6 (Standard/Technical) TG8 (General Purpose) > 10 to 18 > 18 to 30 iso 20457 tolerance table pdf
The standard applies to non-porous molded parts made from thermoplastics, thermoplastic elastomers, and thermosets. If agreed upon by contractual parties, the standard can also be applied to other plastic processes. Amorphous plastics (e
ISO 20457 is the direct international successor to the German national standard DIN 16901, and the two are closely related. However, there are key differences: If agreed upon by contractual parties, the standard
Before ISO 20457, many engineers relied on standards like Germany's to tolerance their plastic components. While useful, DIN 16901 was a national standard that lacked the global recognition needed for international trade.