Injection molding process using transparent plastic as raw material
（1） The process characteristics of transparent plastics: In addition to the common problems mentioned above, transparent plastics also have their own process characteristics. Injection mold factories describe them as follows:
1. The process characteristics of PMMA are high viscosity and slightly poor flowability, which require high material temperature and high injection pressure for injection molding. The influence of injection temperature is greater than that of injection pressure, but increasing injection pressure is beneficial for improving the shrinkage rate of the product. The injection temperature range is wide, with a melting temperature of 160 ℃ and a decomposition temperature of 270 ℃. Therefore, the material temperature adjustment range is wide and the processability is good. Therefore, improving liquidity can start with injection temperature. Poor impact resistance, poor wear resistance, easy scratching, and brittle cracking, therefore, it is necessary to increase the mold temperature and improve the condensation process to overcome these defects.
2. The process characteristics of PC include high viscosity, high melting temperature, and poor flowability. Therefore, injection molding at higher temperatures (between 270-320t) is necessary, and the range of material temperature adjustment is relatively narrow, resulting in lower processability compared to PMMA. The injection pressure has a relatively small impact on fluidity, but due to its high viscosity, a larger injection pressure is still required. Therefore, in order to prevent internal stress, the holding time should be as short as possible. The shrinkage rate is large and the size is stable, but the product has high internal stress and is prone to cracking. Therefore, it is advisable to improve the flowability by increasing the temperature rather than pressure, and to reduce the possibility of cracking by increasing the mold temperature, improving the mold structure, and post-processing. When the injection speed is low, defects such as ripples are prone to occur at the gate. The temperature of the radiation nozzle needs to be controlled separately, the mold temperature needs to be high, and the resistance of the runner and gate needs to be small.
3. The process characteristics of PET are high molding temperature and narrow material temperature adjustment range (260-300 ℃), but after melting, the flowability is good, so the processability is poor, and anti flow devices are often added in the nozzle. The mechanical strength and performance are not high after injection, and can only be improved through stretching and modification. Accurate control of mold temperature is to prevent warping. The important element of deformation, Dongguan Machike Injection Mold Factory recommends using hot runner molds. If the mold temperature is too high, it will cause poor surface gloss and difficulty in demolding. In summary, we can provide a table of injection molding process parameters for your reference during injection molding.
Injection molding process using transparent plastic as raw material
Transparent Plastic Injection Molding Process Parameters Table: Process Parameters Plastic Name Temperature (℃) Pressure (MPa) Speed (rpm) Spray Nozzle Homogenization Section Compression Section Feeding Section Mold Injection Pressure Holding Back Pressure Screw PMMA 180-200 190-210 200-230 180-200 40-90 70-150 40-60 14.5-40 20-40pc 250-270 260-285 270-300 240-270 85-100 80-150 40-70 6-14.7 20-60pet 260-300 265-300 260-295 250-290 68-140 86-120 30-50 4.85 20-70 Alright, the above is a sharing about the injection molding process of transparent plastic as raw material in injection mold factories. We hope that through this article The article can provide some help to readers and friends.
