Injection molding process parameters of the hottes

2022-07-31
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Injection molding process parameters of PP plastics

nozzle 220 ~ 300 ℃ (240 ℃)

the temperature in brackets is recommended as the basic setting value, the stroke utilization rate is 35% and 65%, the ratio of mold flow length to wall thickness is 50:1 to 100:1

melt temperature 220 ~ 280 ℃

constant temperature of barrel 220 ℃

mold temperature 20 ~ 70 ℃

injection pressure has good flow performance, Avoid using too high injection pressure of 80 ~ 140MPa (800 ~ 1400bar)

except for some thin-walled packaging containers, it can reach 180MPa (the machine does not respond after 1 experimental machine point rises (or falls): 800bar)

the pressure maintaining pressure avoids the wall shrinkage of the products, and it takes a long time to maintain the pressure of the products (about 30% of the cycle time); About 30% ~ 60% of injection pressure

back pressure 5 ~ 20MPa (50 ~ 200bar)

injection speed requires high injection speed for thin-walled packaging containers (with accumulator); Medium injection speed is often more suitable for other types of plastic products

screw speed high screw speed (linear speed of 1.3m/s) is allowed. As long as the plasticization process is completed before the end of the cooling time, the metering stroke is 0.5 ~ 4D (minimum ~ maximum) but yes; The 4D metering stroke is very important for the molten material to patiently solve problems whenever they encounter a long residence time.

the amount of residual material is 2 ~ 8mm, which depends on the metering stroke and screw speed.

pre drying is not required; If the storage conditions are not good, it can be dried at 80 ℃ for 1H. The recovery rate can reach 100%. The shrinkage rate is 1.2 ~ 2.5%; High degree of shrinkage; No shrinkage after 24h (shrinkage after forming)

gate system point gate or multi-point gate; Heating hot runner, insulation hot runner, inner casting sleeve; The gate is located at the thickest point of the product, otherwise it is prone to large shrinkage.

the announcement during the shutdown period of the machine indicates that no other materials are required for special cleaning; PP temperature rise resistance

standard screw of barrel equipment, standard three-stage screw; For packaging container products, the geometric shape of mixing section and shear section is special (l:d = 25:1), straight through nozzle and check valve

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