Dynamic Mold Temperature Control

Dynamic mold temperature control (variothermal processing, rapid heat cycle molding) is characterized by actively heating the mold surface to more than 100°C prior to melt injection, and active or passive cooling in the cooling phase.

The research area ‘Dynamic Mold Temperature Control’ at the Chair of Injection Molding of Polymers and the PCCL is focused on both, technologies and processing in rapid heat cycle molding (RHCM) and their effects on polymer part properties:

  • Performance evaluations and investigation of technological and practical limitations of RHCM technologies
  • Experimental research in following fields

    • Appearance of characteristics of surface defects
    • Assessment of surface quality (e.g. homogeneity of surface gloss)
    • Mechanical weld line strength and visual impact of weld lines
    • Sink mark topography and visual impact
    • Influence of RHCM on park shrinkage and warpage
    • Morphology control
    • Influence of RHCM on the filling behavior (filling speed, effective-ness of cavity pressure)

  • Methods and approximations to enable simulation of RHCM processes in common simulation software packages

Thus a multifunctional injection mold has been developed, featuring two RHCM tech-nologies:

  • BFMOLD® for larger areas,
  • high power ceramic heating elements for local RHCM zones, and
  • 3 triple-combined cavity sensors aligned along the flow path (each measures cavity-pressure, melt- and mold-temperature).

The mold was designed to enable the production of several common specimen geome-tries:

  • parts with ribs and cut-outs to generate surface defects,
  • ISO 3167 – tensile specimen,
  • tensile specimen with central weld line, and
  • parts with varying wall thickness