Features of injection mold
The temperature in the injection mold is not uniform and is related to the time in the injection cycle.The function of the mold temperature machine is to keep the temperature constant between 2min and 2max, that is, to prevent the temperature difference from fluctuating in the production process or gap.The following control methods apply to the control of mold temperature: fluid temperature control is the most commonly used method, and the control accuracy can meet the requirements of most cases.Using this control method, the temperature of the controller is not consistent with that of the die.The mold temperature fluctuates considerably because the thermal factors affecting the mold do not directly measure and compensate for changes in the injection cycle, injection rate, melting temperature, and room temperature.The second is the direct control of mold temperature.The method is to install a temperature sensor inside the mold, which is adopted when the mold temperature control precision is required to be high.The main features of mold temperature control include: the temperature set by the controller is consistent with the mold temperature;The thermal factors affecting the die can be directly measured and compensated.Generally, die temperature stability is better than fluid temperature control.In addition, the mold temperature control in the production process control repeatability is good.The third is joint control.Combined control is a combination of the above methods, which can simultaneously control the temperature of the fluid and the mold.In the joint control, the position of the temperature sensor in the mold is very important. When placing the temperature sensor, the position of the shape, structure and cooling channel must be considered.In addition, the temperature sensor should be placed where the quality of the injection molded parts is critical.There are many ways to connect one or more moulding machines to the injection molding machine controller.It is best to use digital interfaces in terms of operability, reliability and anti-interference.
The heat balance control of injection moulds and the heat conduction of moulds is the key to the production of injection moulds.Within the mold, heat from plastics (such as thermoplastic) is transmitted through thermal radiation to the material and steel of the mold, passing over to the heat conducting fluid.In addition, heat is transmitted to the atmosphere and the formwork by thermal radiation.The heat absorbed by the heat conducting fluid is carried away by the mold.The mold's thermal balance can be described as P= pm-ps.Where, P is the heat taken away by the mold temperature machine;Pm heat introduced for plastics;Ps is the heat emitted by the mold to the atmosphere.In the injection molding process, the main purpose of controlling the mold temperature is to heat the mold to the working temperature and to keep the mold temperature constant at the working temperature.If the above two points are successful, the cycle time can be optimized to ensure a stable high quality of injection parts.Mold temperature can affect surface quality, fluidity, shrinkage, injection cycle and deformation.If the die temperature is too high or not enough, it will have different effects on different materials.For thermoplastics, high mold temperature usually improves surface quality and fluidity, but extends cooling time and injection cycle.A lower mold temperature will reduce the shrinkage in the mold, but will increase the shrinkage of injection parts after demoulding.For thermosetting plastics, higher mold temperatures usually reduce cycle times, which are determined by how long it takes for parts to cool down.In addition, in the plastic processing, higher mold temperature will also reduce the plasticizing time, reduce cycle times.