Tight tolerances, tight schedule: SIGMASOFT® Virtual Molding helps
Kalypso Ultra Technologies, based in Ottawa, Ohio, USA, was confronted with the challenge of developing a motor mounting part, made from PA 6,6 with 30% glass fiber reinforcement. The part had a 100 mm diameter, with large thickness and geometry variations, and the narrow tolerances around each diameter were +0.07/-0.00 mm (Figure 1).
Kalypso faced a number of issues in developing this part: the behavior of the material being used was difficult to predict due to the crystallization and the fibers, so ‘normal’ design rules did not apply; the geometry was exceptionally complex, so prior experience with similar shapes was limited, and the part had to be created within the extremely close tolerances. Furthermore, optimized gating and reliable thermal control were critical for the success of this project.
Faced with the option of using ‘trial and error’, multiple iterations and the possibility of mold rework that would have taken time and result in missing the delivery date, or using simulation to run a virtual project, Kalypso decided to use SIGMASOFT®.
A multi-cycle analysis consisting of 20 consecutive virtual production cycles using actual process parameters and conventional cooling revealed hot spots on the mold cores (Figure 2) during the steady production state of the mold. Hot spots are difficult to manage in a production mold and they influence part distortion because they create variations in crystallization, resulting in non-uniform shrinkage and distortion. Reducing water temperature typically only makes the cold areas colder and increasing cooling time is expensive, so these common strategies don’t always work. As an alternative, a potential solution using conformal cooling in the mold cores was discussed and then evaluated, virtually. In this case, the consideration of all mold components and process parameters over several cycles showed a more regular temperature distribution inside the mold (Figure 3) as well as a reduction in cycle time.
Based on this new information, the mold was built and the process parameters were predetermined. The production staff was specifically prepared for the required process in advance to avoid wasting time during the physical trials at the molding machine. The new mold and process produced the required part quality from the start. Kalypso was able to deliver the mold and process to their customer on schedule and to achieve first-shot success during the molding trial.
All pictures by Kalypso Ultra Technologies.