Some mold builders will elect to buy the hot runner components, machine the hot half plates and install the system themselves to save money. In these cases, there are two options available.

The first is to purchase the standard hot runner components as individual items. The system will be delivered unwired and requires assembly. The installation entails installing the nozzles and manifold then wiring all components and testing the electrical aspects of the system. Although there may be a perceived cost advantage, there is a risk in doing this. Incorrect installation or failure to machine the plates correctly to meet the cold clearance requirements of the hot runner within the manifold frame plate can result in a catastrophic leakage of the hot runner. Also, the installation of the hot runner components will consume valuable mold building time not to mention the cost of labor.

A more attractive solution is to purchase a unitized or drop-in hot runner that is delivered in a fully assembled state and ready to—as the name implies—drop into the hot half plates machined by the mold builder. The nozzles are screwed into the manifold at the factory thereby eliminating any potential for leakage even if the cold clearance is not correct. The systems are shipped pre-wired and tested. In the case of valve gate systems, they are also pre-plumbed and tested. The advantage to the moldmaker is a greatly reduced installation time and the elimination of any risk.