Hot runner is through the heating way to guarantee runner and gate plastic keep molten state. Hot runner system is general by hot nozzle, shunt board, temperature control box and accessories and so on several parts. Hot nozzle generally includes two kinds: open hot nozzle and needle valve type hot nozzle. Due to the hot nozzle form directly determine hot runner system selection and mold manufacturing, so often the corresponding will hot runner system into open hot runner system and needle valve type hot runner system. Cold runner system in every open die will cause waste, in injection molding parts, mold cold runner system will cause a lot of raw material waste, this makes the molding of the profit space badly damaged. The advantage of the cold runner is easy to use, also can well satisfy some beautiful demand. The cold runner can reduce the injection to pervious to light transparent acrylic ester or polycarbonate etc parts, avoid injection in some part causes visible banded effect. For the cold runner shortcomings, in addition to the waste of raw materials outside, cold runner defects including make whole automation or artificial process added steps. Will the cold runner from mould parts removed, need to robots or workers put the parts and separate flow. According to the size of the runner, the value of the waste may have reached hundreds of thousands of dollars, especially for polycarbonate expensive material. For more cavity system, cold runner may also not satisfactory. In many cavity, gate plastic will exceed the amount of injection molding parts. At that time, gate cooling time will more than injection molding part of the cooling time, making mould user cycle time by the gate cooling time control, the processing situation is difficult to satisfactory. And hot runner can solve this problem, it can effectively increase the total number of single cavity, because gate in the whole machining process are in molten state.
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