Molding is a complex business. From a technical perspective there is much to know. Molders must be versed in materials science and the workings of a molding press.

They must know about hydraulics and electrical controls. And they should even be at least “shade tree” tooling experts, familiar with steels, heat treating, runners and gates, and mold cooling.

Of these tooling facets, it could be argued that mold cooling is one of the most important. A slight difference in cooling conditions can add or subtract seconds from the molding cycle, making the difference between a profitable molding job and a loser. Critical dimensions, surface finish, and part warpage are all affected by cooling conditions. It is ironic, then, that mold cooling is the neglected stepchild in many molding shops. We have all sorts of “gee-whiz” technology for monitoring and controlling nearly everything but mold cooling.

Like most things, there is more to know about the finer points of mold cooling and heat transfer than most of us care to learn. In fact, you could probably write a good PhD dissertation on mold cooling if you wanted to. But we’re not going to consider those complexities here. Although most molders have an idea of what mold temperature they need, they often have no idea how many gallons per minute of water they need through a cooling circuit or what size hose and fittings to use. These are some of the simple, common sense things to know on this subject; useful, well-conceived products can give you better information and control over mold temperatures. This article aims to help you gain a better understanding of mold cooling and to be helpful in your molding efforts.