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Injection molding plastics process parameters
by：CSSSLD
2021-02-03
Cylinder temperature and nozzle temperature mainly affects plastic plasticizing and melt flow, because of its many factors influence, generally through the empty before molding injection molding or injection molding processing of plastics parts of visual analysis method to adjust, so that to determine the best material barrel temperature and nozzle temperature.
Mold temperature mainly affects the flow of the plastic inside the cavity and cooling, it depends on the crystalline plastics, the size and structure of the product, performance requirements, and other process conditions.
annealing treatment is plastic parts in a constant temperature heating liquid medium, or placed in hot air circulation drying oven let stand for a period of time, and then slowly cooling process. Its purpose is to reduce or eliminate the internal stress of parts. Wet processing is just mould parts in the air in the hot water to prevent oxidation annealing, at the same time to speed up the moisture absorption equilibrium a post-processing method. The purpose is to make the color of the parts, size stability. Polyamide type of plastic parts often need to wet processing.
when choosing the nozzle temperature, due to considering the plastic melt spray nozzles and friction between the heat melt through the nozzle after the high temperature, so as to prevent the melt flow in straight through the nozzle may delay phenomenon, often make the nozzle temperature slightly lower than the highest temperature of cylinder. But for thermosetting plastics, generally make the nozzle temperature higher than the cylinder temperature. So, on the one hand, make its have good liquidity, on the other hand can close to the critical value of hardening temperature again, not only ensure the injection molding, and is helpful for hardening.
is the most important process parameters of injection molding, such as temperature, pressure and time. In injection molding to control the temperature of the material barrel temperature, nozzle temperature, mold temperature, etc. Cylinder temperature should be controlled in between viscous flow temperature and thermal decomposition temperature of plastic. Cylinder temperature directly affects the plastic melt molding process and the quality of the parts. High temperature in the cylinder, is advantageous to the injection pressure to pass into the mold cavity. In addition, can reduce the melt viscosity, improve liquidity, improve formability, increase productivity, reduce the surface roughness.
cylinder temperature is too high, plastic stay too long in the cylinder, the thermal degradation of plastic volume will increase, the quality of the parts will be affected by a lot of. For plastics such as pom, PVC, we will strictly control the highest temperature of the cylinder and the residence time in the cylinder. Glass fiber reinforced thermoplastics due to poor liquidity and to improve the temperature of the material, appropriate for thermosetting plastics, to prevent melt in early hardening occurs in the cylinder, cylinder temperature tends to take a small value.
gate freeze after cooling begin when gate of plastic melt completely frozen, this one phase within the cavity melt to continue cooling, no melt flow into or out from the gate, but there are still a small amount of cavity flows. Should point out that the melt after injection mold cavity is cooling, until when demoulding. To improve the performance and improve the injection molding processing of plastics product, and dimensional stability, after stripping or machining parts should be proper post-processing. Post-processing is mainly refers to annealing and wet processing.
screw injection molding machine due to the effect of shear of the screw rotates can obtain larger frictional heat, promote the plasticization of plastic, and cylinder temperature selected 10 ℃ - is lower than that of the plunger machine 20℃。 Thin-walled parts the narrow cavity plastic melt injection when the resistance is big, the cooling block, cylinder temperature should choose a few higher, lower conversely. For complex shape or of parts with embedded parts, or when the melt molding process more twists and turns, or longer, material barrel temperature also should choose a few higher. Cylinder temperature is not uniform, but starting from the hopper side until nozzle is gradually rise, can make the melt temperature rising steadily so as to achieve the purpose of uniform plasticizing.
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annealing treatment is plastic parts in a constant temperature heating liquid medium, or placed in hot air circulation drying oven let stand for a period of time, and then slowly cooling process. Its purpose is to reduce or eliminate the internal stress of parts. Wet processing is just mould parts in the air in the hot water to prevent oxidation annealing, at the same time to speed up the moisture absorption equilibrium a post-processing method. The purpose is to make the color of the parts, size stability. Polyamide type of plastic parts often need to wet processing.
when choosing the nozzle temperature, due to considering the plastic melt spray nozzles and friction between the heat melt through the nozzle after the high temperature, so as to prevent the melt flow in straight through the nozzle may delay phenomenon, often make the nozzle temperature slightly lower than the highest temperature of cylinder. But for thermosetting plastics, generally make the nozzle temperature higher than the cylinder temperature. So, on the one hand, make its have good liquidity, on the other hand can close to the critical value of hardening temperature again, not only ensure the injection molding, and is helpful for hardening.
is the most important process parameters of injection molding, such as temperature, pressure and time. In injection molding to control the temperature of the material barrel temperature, nozzle temperature, mold temperature, etc. Cylinder temperature should be controlled in between viscous flow temperature and thermal decomposition temperature of plastic. Cylinder temperature directly affects the plastic melt molding process and the quality of the parts. High temperature in the cylinder, is advantageous to the injection pressure to pass into the mold cavity. In addition, can reduce the melt viscosity, improve liquidity, improve formability, increase productivity, reduce the surface roughness.
cylinder temperature is too high, plastic stay too long in the cylinder, the thermal degradation of plastic volume will increase, the quality of the parts will be affected by a lot of. For plastics such as pom, PVC, we will strictly control the highest temperature of the cylinder and the residence time in the cylinder. Glass fiber reinforced thermoplastics due to poor liquidity and to improve the temperature of the material, appropriate for thermosetting plastics, to prevent melt in early hardening occurs in the cylinder, cylinder temperature tends to take a small value.
gate freeze after cooling begin when gate of plastic melt completely frozen, this one phase within the cavity melt to continue cooling, no melt flow into or out from the gate, but there are still a small amount of cavity flows. Should point out that the melt after injection mold cavity is cooling, until when demoulding. To improve the performance and improve the injection molding processing of plastics product, and dimensional stability, after stripping or machining parts should be proper post-processing. Post-processing is mainly refers to annealing and wet processing.
screw injection molding machine due to the effect of shear of the screw rotates can obtain larger frictional heat, promote the plasticization of plastic, and cylinder temperature selected 10 ℃ - is lower than that of the plunger machine 20℃。 Thin-walled parts the narrow cavity plastic melt injection when the resistance is big, the cooling block, cylinder temperature should choose a few higher, lower conversely. For complex shape or of parts with embedded parts, or when the melt molding process more twists and turns, or longer, material barrel temperature also should choose a few higher. Cylinder temperature is not uniform, but starting from the hopper side until nozzle is gradually rise, can make the melt temperature rising steadily so as to achieve the purpose of uniform plasticizing.
more excellent articles: injection molding processing outbound order, just click.
http://www。 csssld。 cn//html/2017/Info_0725/641。 HTML
nantong on suye's official website: http://www. csssld。 Cn / /
more wonderful articles, immediately search: changshu da plastic products factory smoothly
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