The traditional injection mold is called a cold runner mold. After each injection is completed, there will be a section of cooling and solidifying runner that needs to be removed manually or mechanically after the mold is opened. And the mold with the hot runner system (including hot nozzle, hot manifold, temperature controller, etc.) is called the hot runner mold.
Compared with cold runner mold, hot runner mold has the following advantages:
① When the wall thickness of the product is thin, make sure that the melt can reach the part far from the gate (inlet), greatly reduce the degree of deformation of the product, and greatly improve the product surface quality and product consistency.
② The pressure loss in the flow channel is small, the melt has good fluidity, and the density is easy to be uniform, which avoids defects such as deformation, peak peaks, unstable dimensions and color difference of the injection molded part.
③ All or most of the handles (outlet materials) are eliminated, and the nozzles do not need to be cut manually, no further pulverization is needed, which improves the utilization rate of materials, saves energy, and improves production efficiency.
④ Eliminate the additional heat brought by waste material, the cooling cycle of the mold is only the cooling time of plastic, shortening the processing cycle.
⑤ The hot runner is automatically cut off the gate to improve the appearance of the gate and increase the degree of automation.
⑥ The precise control of the melt plastic temperature eliminates the degradation of the material, makes the holding time more reasonable, and reduces the internal stress of the product.
Because of these advantages of the hot runner system, more than 70% of the injection molds in developed countries such as Europe, America, and Japan use the hot runner system.
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