Cold vs Hot Runner Molds

Hot vs cold runner molds Most people understand that plastic parts are made using molds. However, what they might not realize is that there are two very different kinds of molds that are utilized when producing plastic parts. They are called cold runner molds and hot runner molds. Let’s take a look at some of the things that differentiate the two.

Cold runner molds

Cold runner molds are made up of either two or three plates located within the base of a mold. When cold runner molds are used, plastic is injected inside of the mold where it fills the runners that lead directly into the cavity. With molds that use two plates, the runner system and the parts are attached to one another and there is an ejection system that is utilized to separate the two of them from the mold when it’s finished. With molds that use three plates, meanwhile, the runner exists on a separate plate and the plastic parts are alone when they are ejected.

Hot runner molds

Unlike cold runner molds, all hot runner molds are made up of two plates that are heated up during the production process. A manifold system is used to provide the heat, and that system is what sends melted plastic down into the mold using either external or internal heat. Externally heated systems are ideal for using with polymers that might be sensitive to heat changes, while internally heated systems will provide you with better flow control. Hot runner molds don’t rely on runners, which cuts down on waste.

There are many pros and cons to using cold and hot runner molds. Cold runner molds, for example, are more affordable and allow for quicker color changes with plastics. But hot runner molds are quicker overall and can be used when putting together larger parts. You should consider all of the advantages and disadvantages of using one mold versus the other before you decide which would be best for you.

Bridgville Plastics can help you produce plastic parts by using either of the molds mentioned here. Contact us at 269-465-6516 today to learn more about which mold would be better for your specific needs.