Injection temperature is an important factor affecting injection pressure. The injection molding machine barrel has 5-6 heating sections, and each raw material has its appropriate processing temperature (detailed processing temperature can be found in the data provided by the material supplier). The injection temperature must be controlled within a certain range. The temperature is too low, resulting in poor plasticization of the molten material, which affects the quality of the formed parts and increases the difficulty of the process; If the temperature is too high, the raw materials are prone to decomposition. In the actual injection molding process, the injection temperature is often higher than the barrel temperature, and the higher value is related to the injection rate and material performance, up to 30 ℃. This is caused by the high heat generated by the shear of the molten material passing through the injection port. There are two ways to compensate for this difference in mold flow analysis: one is to measure the temperature of the melt during injection molding into the air, and the other is to include the nozzle during modeling.

Back pressure refers to the pressure that needs to be overcome when the screw rotates backwards to store material. Adopting high back pressure is beneficial for the dispersion of pigments and the melting of plastics, but it also prolongs the screw retraction time, reduces the length of plastic fibers, and increases the pressure of the injection molding machine. Therefore, the back pressure should be lower, generally not exceeding 20% of the injection molding pressure. When injecting foamed plastics, the back pressure should be higher than the pressure formed by the gas, otherwise the screw will be pushed out of the barrel. Some injection molding machines can program back pressure to compensate for the reduction in screw length during melting, which reduces input heat and causes a temperature drop. However, due to the difficulty in estimating the results of such changes, it is not easy to make corresponding adjustments to the machine.