Dimensional accuracy standards DIN ISO 20457 and DIN 16742

The DIN ISO 20457 "Molded Plastic Parts - Tolerances and Acceptance Conditions" has been in effect since February 2020. Dirk Falke served as chairman of the international standards committee on behalf of the VDWF. The standard specifies the dimensional accuracy of plastic parts that can be achieved with today's manufacturing process. The October 2013 DIN 16742 "Molded Plastic Parts - Tolerances and Acceptance Conditions", served as a template. Chairman Dirk Falke and association President Prof. Dr. Thomas Seul were part of the national standards committee.


Broadly, the need for the standard is due to globalization and the associated international division of labor. It must be possible to assemble components which are produced in different countries. In addition, products are sometimes manufactured simultaneously at several locations, but have different dimensional tolerances. The problem with molded part drawings or specifications is often an excessive demand on dimensions which do not necessarily ensure the function of the components. But ensuring proper function is the entire purpose of dimensions and tolerances. The second widespread problem is that molded part drawings often specify tolerances which cannot be met under the given conditions, and which sometimes cannot even be measured reliably. When the dimensions of a molded part are not within the specified tolerances, but do fulfill their function, the DIN ISO 20457 and DIN 16742 help prevent against "fear tolerances" and unnecessarily high accuracy requirements for components and injection molding tools.