Hot runner molds is a generally effective method of mold making that has less scrap (sometimes the process has no scrap) due to keeping the plastic is kept above the melting temperature. Because it is more effective, it tends to be a bit more expensive than other types of molds, particularly cold runner molds. The overall savings makes up for the cost if you have large quantities to produce or if you need quick production.
Components and Process
All hot runner mold systems include two plates to complete the process quickly. It is composed of the manifold and drops. The purpose of the manifold is to convey the plastic to an area above the cavity.
Running perpendicular to the manifold are the drops, which move the plastic from the manifold to the part. Systems have some variations based on the method of heating the plastic.
Things to Consider
In addition to reducing the waste, hot runner molds have a quicker cycle time. Robotics are common in many molding processes, but you will not need as many for a hot running system. Large parts are typically best when made with hot runner molds because these molds can better accommodate the size.
However, if you have a more limited budget or fewer parts, you can save on the cost by using a cold runner system. If color is important and you are likely to need to change it frequently, hot runner systems will not be able to make the change easily.