Mold temperature is usually controlled by the cooling medium through the constant temperature; also by the melt into the mold naturally heating and natural cooling to achieve a balanced way to maintain a certain temperature; in special circumstances, also available resistance wire and resistance heating rod pairs The mold is heated to keep the mold constant. But no matter what, for the plastic melt, are the cooling process.
The cylinder temperature should be between the viscosity flow temperature (or melting point) and the thermal decomposition temperature. The plunger cylinder temperature is higher than the screw barrel temperature 10 ~ 20 ℃. Plastic parts and mold structure features: for thin-walled parts cylinder barrel temperature is higher than the thick-walled parts; complex shape or with the embedded parts cylinder temperature should be higher.
Barrel temperature distribution, generally follow the principle of high to low before the barrel that is the lowest temperature,
The nozzle has the highest temperature. For the screw injection machine to prevent the screw and the melt, the melt and the melt, the melt and the friction between the barrel and the plastic heat caused by thermal degradation, the cylinder can be slightly lower than the middle of the middle section.
Determine the barrel temperature is appropriate, can be used to observe the air injection or direct observation of the quality of plastic parts is good or bad. For empty injection, if the material is uniform, smooth, no foam, uniform color that is appropriate temperature; if the material is rough, there are silver or discoloration phenomenon, then the material temperature is not appropriate.
2. Nozzle temperature
Generally slightly below the maximum temperature of the barrel to prevent the melt in the nozzle at the salivation phenomenon. But not too low, otherwise the melt in the nozzle will appear early coagulation and nozzle clogging, or early pouring into the mold cavity and affect the quality of plastic parts.
Mold temperature depends on the level of plastic properties, plastic parts size and structure, performance requirements and other process conditions. Mold temperature ↑, flow ↑, density and crystallinity ↑, shrinkage and productivity ↓.
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