Dimensional accuracy

The most important task for the toolmaker is to deliver dimensionally accurate parts within the specified tolerances. Here, we distinguish between:

  • Dimensional accuracy of the form
  • Dimensional accuracy of the contour

The more critical a process is with regard to the adherence to tolerances, the more the maximum accuracy of the solid simulation helps you to have early security of a correct process.

Dimensional accuracy of the shape of the final part

The dimensional accuracy of the shape of the component is inseparably linked to the issue of springback. It is often not difficult to bring a part into the desired shape. However, if you take it out of the press, elastic energy is released which can dramatically change the shape of the part.


After taking the part out of the press, one has typically one of the following problems:

  • Sink marks: Unevenness occurs and the flatness of the component is lost
  • Joining problems: The component can no longer be screwed or riveted


For good method planning it is therefore essential to know as early and as precisely as possible about the springback of the component in order to be able to take countermeasures. In most cases:


  • the designer overbends the component, possibly even in an additional calibration station.
  • the designer introduces more plastic deformation. This significantly reduces springback.


With both approaches, however, it is essential that the die designer verifies the changes afterwards in the simulation. For the best springback results we recommend:

  • Solid simulation: Shortly before the press is closed, any local thickening is strongly compressed. This has a high influence on the springback, but is only correctly reproduced in the solid simulation, as the shell does not sufficiently reproduce stresses and strains along the thickness.
  • To use the same press force in the simulation, which is also used on the real press.
  • Use the "kinematic hardening law" integrated in Stampack to map the physical material even more accurately.


Dimensional accuracy of the contour of the final part:

In most cases the contour of the initial blank is determined with an inverse one-step, which is included in all common CAD systems. However, since this method does not take into account physical forming process or the exact method of the multi-step process, the result often deviates significantly from the desired target part, resulting in unsightly artefacts or even in wrong feasibility results. The Trim Optimizer optimizes the initial blank or intermediate cutting lines in such a way that after forming the desired target contour is achieved within a specified tolerance.