Extrusion Minimum Runs Measured in Tonnes Rather than Pieces
Extrusion runs are quoted in tonnes because start-up scrap, thermal equilibration, and bulk resin compounding operate as continuous mass processes.
DIN 16941
Meaning
Manufacturing standard specification establishes permissible dimensional tolerances and acceptance criteria for extruded thermoplastic profiles. Applying DIN 16941 provides standardized tolerance classes for plastic extrusions, categorizing dimensions by cross-sectional size and material stiffness. Engineering drawings cite this standard to define acceptable cross-sectional deviations across custom profile geometries.
Tolerance Class
Material classification groups rigid and flexible polymers into distinct accuracy bands based on thermal expansion and post-extrusion shrinkage rates. Profile dimensions governed by DIN 16941 fall into standard or fine tolerance categories depending on tooling capability. Rigid PVC profiles typically meet fine tolerance bands, whereas flexible plasticized profiles require wider allowances due to elastic recovery during cooling.
Measurement Rule
Verification protocols require cross-sectional measurements to occur at room temperature after twenty-four hours of conditioning. Evaluating parts under DIN 16941 excludes initial die swell variations and temporary thermal distortion caused by uneven cooling bath immersion. Optical comparators measure wall thickness and angular alignment without applying mechanical contact pressure to soft profile sections.
Fit Boundary
Functional fit requirements for mating window frame profiles demand strict adherence to medium tolerance limits. DIN 16941 does not cover longitudinal bow or twisting along the length of extruded profiles, which require separate straightness specifications.