• The orientation ranges of the melt temperature (melt or plasticizing temperature) are determined by rheological conditions, quality requirements and thermal stability.
  • The injection pressure causes a temperature increase of the melt due to shear heating. This cooling time part is taken into account by a program-internal estimation of the injection pressure on the basis of a molding-specific minimum pressure.
  • The evaluation of the flow resistance of the molding and sprue contours is based on the user's experience. The flow resistance includes the relation of flow distance to flow cross-section, whereby the impact of melt direction changes is almost insignificant.


The mold contours are filled from the nozzle (sprue) or from the gate (molded part) by a laminar source flow, provided the melt does not solidify before mold filling is complete. For a given flowability (viscosity) of the melt, the most effective flow extension or shortening of the filling time is achieved by increasing the melt temperature and/or the injection pressure. Melt redirections have only an insignificant effect on the flow resistance. Due to the thermal insulation of the solidifying surface layers, increasing the mold contour temperature only slightly reduces the flow resistance, but significantly increases the cooling time. Increasing the flow cross-section (e.g. by increasing the wall thickness) reduces the flow resistance disproportionately. With regard to the effect of wall thickness on the flow resistance of flat mold contours, the following wall thickness classification should serve as a guide:


    • below 1 mm = very thin-walled
    • 1 to 2 mm = thin-walled
    • over 2 to 4 mm = normal wall
    • over 4 mm = thick-walled


For wall thicknesses below 0.5 mm, reliable mold filling is not always guaranteed, even with small flow distance lengths.


  • The software-internal orientation ranges of the melt temperature represent the most common temperature ranges in practice.
  • The melt temperature ranges are determined according to the thermal stability of the melt and the flow conditions of the mold filling, as well as according to the molded part quality (surface gloss, weld line quality) that depends on them. If the melt temperatures are defined within the specified ranges, the cooling time is influenced relatively little.
  • The mold contour temperature, on the other hand, has a significant impact on the cooling time. Low cooling time (high productivity) requires low contour temperatures, while special molding quality requires correspondingly high temperatures. The choice of the "correct" contour temperature is always a compromise which, with regard to the quality of the molded part, can only be decided by production trials. The practical experience of the user is very important here. Otherwise, the possible cooling time deviations must be tested by input variations, whereby the respective purpose of the cycle time calculation (e.g. cost pre-calculation, machine occupancy, machine setting) allows appropriate conclusions to be drawn.
  • A further precision of the temperatures is possible by communication with experience carriers (e.g. molding manufacturers, molding mass manufacturers).
  • Proponents of impulse cooling frequently claim, among other things, the advantage of a strong reduction in cooling time. In fact, this claim is neither theoretically nor practically proven, provided verifiable investigations are evaluated.