There are several mistakes in runner system design concept

A injection machine even if the mold design can meet the demand of the performance of the products at the lowest cost, may also be because flow design is not reasonable and become cost is not economic. Before the runner system established, people can through the CAD program to all sorts of design of gate and runner, once the runner system was set up, any modification is very limited.

in the past, people to the concept of reasonable flow design has a few mistakes. For cold runner systems, for example, that the greater the flow channel, the greater the molten material into the cavity, this actually means that the quench cycle longer, injection and machine volume requires a larger size, so that produce more of the scrap, rework cost and the increase of pollution; The projection area is larger, which need more mould clamping force, etc. In order to obtain higher benefits, people have to spend a lot of manpower and material resources mould, flow and cavity of the renovation work.

in the 1960 s has been into mass industrial production mould of hot flow path, in the past decade have become more common. The benefits of the hot runner system is to eliminate the cold runner, can in the process of plastic from the nozzle to the mold cavity to prevent its cooling, thus shortening the cycle. Other benefits include increased vessel, reduce the injection pressure, raw material requirements, gate to improve appearance. But the hot runner is not applicable to certain plastics and certain configurations of products.