Process
Cycle time is the total time from one mold closing to the next mold closing for a part: the sum of the closing, injection, holding, cooling, plasticizing, opening and ejection phases. The cooling phase takes 50–70% of the cycle and grows with the square of the wall thickness; a 2.5 mm wall instead of 2.0 mm lengthens cooling time by about 56%. Cycle time is also the main determinant of cost per part and of energy.
The order in which you shorten the cycle matters: first cooling (mold temperature, channel flow rate, wall thickness), then holding time (verified by weighing), then movement times. Plasticizing should run in parallel with cooling; if plasticizing takes longer than cooling, the bottleneck is the screw.
Keeping the mold wall 10 °C warmer lengthens the cooling phase by roughly one fifth. This is where the power of the temperature control unit setting over the cycle comes from; but a low mold temperature carries a price in internal stress, low crystallinity and post-shrinkage.
From the wall thickness, the thermal diffusivity of the material and the melt, mold and ejection temperatures. The calculator takes these values from the material table and gives a guide cooling time; the real value is verified in mold trials.