Mold temperature control
Hot runner mold temperature is controlled by a system,which includes temperature control box,heating coil and nozzle.
1. method for mold temperature control
there are several ways available methods such as steam, hot oil circulation, , and the resistor to heat the Plastic mold for controlling its temperature. The circulating cooling water or air could be used to cool down the mold temperature. Injection molding machine often adopt the heating from resistor and the cooling from the cooling water circulation.
When we use resistance heating to heat plastic mold,plate location adopt resistor ,mold body is heated with electric rods and cylindrical parts is heated with electric coil.Cooling water circulation could be placed to location where the temperature need be decreased.
Both Resistance heating and cooling water circulation need to work alternately to meet mold working demand, so that the mold temperature could be controlled on required temperature range in the process .
2.Precautions for Mold temperature control
1)After heating , temperature of the various parts of plastic mold should be uniform to ensure that the melt has a good filling quality,also injection molding quality could be assured, so that the pass rate of the final products could be raised.
2)specific temperature regulation of injection molding process should be based on the level of melt viscosity. When higher viscosity molten material is injected into the mold, the specific temperature should be adjusted to be slightly higher; while it is for lower melt viscosity plastic material, lower mold specific temperature may be appropriate . In preparation for the molding production, the mold temperature must be within the scope of the process requirements. In order to ensure uniform mold temperature, the mold heated should be keep a specific temperature for some time.
3)When injecting large plastic products is needed, due to the mass molding melt quantity and the bigger runner channel ,the runner channel of large plastic mold should be kept temperature to prevent the longer runner channel,which would increase the viscosity of the molten material to slow down the melt material flowing speed.This could impact injection molding filling quality,or even result in the solidification of the front of flowing plastics, so that the injection work of injection molding machine can not be carried sometimes.
4) The plastic mold should be designed for reducing the runner channel length which could leads in temperature decreasing of melt material and increases the heat loss ,also an insulation layer should be added between the low temperature part and runner channel with high temperature.