I was recently asked the question…

You can reduce your cooling time a couple ways. The first way to reduce cooling time is to increase your rate of heat transfer. That means you must increase the thermal conductivity of your mold material The second way to reduce your cooling time is to move your cooling lines closer to the mold cavity surface. By reducing the distance between your cooling lines and cavity surface you effectively reduce the thermal gradient between your cooling fluid and polymer melt.

The amount you should invest into increasing the efficiency of your cooling is dependent on many factors. You must perform a cost analysis on your expected output with different cooling system designs. Use the expected cooling time and cost of each cooling system in your business plan to determine which design is most cost effective for you. 

Be aware that a thermal conductivity value five times greater than steel will not result in a five times greater cooling rate. The cooling rate will become limited by the heat conduction through the plastic and the heat convection to the mold coolant.

-Andy