Heating and Cooling

When evaluating cost-reduction projects in injection molding, the discussion typically centers around cycle-time reduction and the cost to implement the change. This article explores the true value of conformally cooled injection mold in a very specific case. That case is when the molder can sell more product than it can make on a 24/7 basis.

Mold-temperature control is just one of many process elements that can affect the quality of an injection molded part. In a perfect world, anyone running a particular mold would know what the mold designer set as the ideal temperature and flow rate for the cooling water. In reality, operators and setup personnel don’t always know these settings and/or something changes so that it is necessary to re-establish them by trial and error.

The first law of thermodynamics states that energy cannot be created or destroyed, but only transferred from one place to another. If you think of an injection mold as a closed thermodynamic system, you can account for the energy entering and leaving the system. A shot of molten plastic injected into a mold is the energy input, and energy leaves by various mechanisms. Some of the energy (heat) is carried away in the ejected parts and some is removed by the cooling system. It is less obvious, but some energy will also go into the surrounding environment when a mold is heated substantially above room temperature.