Injection technology of polycarbonate
PC known as polycarbonate, due to their excellent mechanical properties, commonly known as bullet-proof plastic. PC has high mechanical strength, wide temperature range, good electrical insulating properties (ARC-proof performance remain unchanged), good dimensional stability, transparency and so on. Electrical products, electrical housings, electronics components are widely used. Modification of PC products more, usually with glass fiber, mineral fillers, chemical flame retardants, plastic and so on. PC less liquidity, higher processing temperature, its many levels of modification of structure of materials processing requires specialized plastic injection.
1, plastic handle
greater water absorption rate of PC, be sure to preheat drying before processing, pure dry PC 120 ℃, the modified PC 110 deg is commonly used to dry for 4 hours or more. Drying time should not exceed 10 hours. Generally available to empty out method to determine whether the dry enough.
proportion of renewable materials used up to 20%. In some cases, can be 100% using recycled materials, depending on the actual amount depends on the product quality requirements. Renewable materials cannot mix different color masterbatch, otherwise it will seriously damage the properties of the finished product.
2, and injection machine of selection
now of PC products due to cost and the other aspects of reasons, more with modified sex material, especially electrical products, also must increased fire performance, in flame retardant of PC and other plastic alloy products forming Shi, on injection machine plastic of system of requirements is mixed good, and resistance corrosion, General of plastic of screw rod to do, in purchase Shi, must to advance description. Ramada limited company has a dedicated PC screw for customers to choose.
3 mold and runner design
common mold temperature 80-100 ℃, and glass fiber as 100-130, small size available needle-shaped gate, gate depth should be the thickest parts of the 70%, and other gate circular and rectangular.
gate, the bigger the better, to reduce defects is caused by excessive cutting of plastics.
vent depth should be less than 0.03-0.06mm, runners short and round.
roughly 30 '-1 ° by stripping slope.
4, the melt temperature
can be used to determine the temperature of air injection. General PC processing temperature 270-320 ℃, some modified low molecular weight or PC as 230-270 c.
5, injection speed
fast speed forming, such as electrical switches. Common for slow → fast molding.
6, back pressure
back pressure of 10bar, where there is no gas lines and the color mixer case can be appropriately reduced.
7, residence time
residence time at high temperature for too long, the material will degrade, CO2, turns to yellow. Do not use LDPE, POM, ABS/PA clean barrel. PS cleanup.
some modified PC, due to too many (molecular weight reduction) or uneven mixing various components, easy to produce a dark brown liquid bubble.
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