Polypropylene PP known for its anti-break performance, also known as "pleated plastic." PP is a semi-transparent, semi-crystalline thermoplastic with high strength, good insulation, low water absorption, high temperature heat on the shape, density, crystallinity and high degree. Modified filler usually glass fibers, mineral fillers, thermoplastic rubber.
Different uses of PP their mobility are quite different, the general use of the PP flow rate range between ABS and PC.PRM IndustryAbstract...Articles section 1, plastic handle
PP is a translucent ivory pure white, can be dyed various colors. Staining of PP injection molding machines in general can only be used on the masterbatch. Ramada on the machine to strengthen the role of independent mixing and plasticization component, can also be stained with dye. Outdoor use of the products, general use of UV stabilizers and carbon black filled. The proportion of recycled material used should not exceed 15%, otherwise it will cause discoloration and decomposition strength decreased. PP injection generally do not need special processing before drying.
2, injection molding machine used
The selection of the injection molding machine has no special requirements. As the PP high crystallinity. Requires the use of higher injection pressure and can be computer controlled multi-stage injection molding machine. Clamping force is generally determined by 3800t/m2, injection volume can be 20% -85%.
3, mold and gate design
Mold temperature 50-90 ℃, the size requirements for a high temperature with high modulus. Core temperature lower than the cavity temperature above 5 ℃, flow channel diameter of 4-7mm, needle-shaped gate length of 1-1.5mm, diameter as small as 0.7mm. Polygon gate length as short as possible, about 0.7mm, a depth of half the thickness, width of twice the wall thickness and the cavity with the melt flow length increased by Ken. Mold must be of good exhaust, vent deep 0.025mm-0.038mm, thickness 1.5mm, to avoid scar contraction, it is necessary to use large, round and round nozzle flow channel, the thickness of the ribs is smaller (eg is the wall thickness of 50-60%). PP homopolymer manufactured products, the thickness of not more than 3mm, or there will be bubbles (thick-walled products can only be used copolymer PP).
4, melt temperature
PP melting point of 160-175 ℃, decomposition temperature is 350 ℃, but when the temperature is set in the injection process can not exceed 275 ℃. Melting temperature, preferably at 240 ℃.
5, injection speed
To reduce the internal stress and deformation, should choose high-speed injection, but some level of PP and mold is not applicable (person mantle are bubbles, gas lines). Such as the engraved surface of the gate pattern of the spread of light and dark stripes, then use the low-speed injection and higher mold temperature.
6, melt back pressure
Available 5bar melt back pressure, back pressure can be properly colored powder to increase.
7, injection and holding pressure
A higher injection pressure (1500-1800bar) and holding pressure (injection pressure of approximately 80%). Around 95% of the whole trip transfer packing, with a longer dwell time.
8, products of post-processing
Produced after crystallization in order to prevent shrinkage, products normally subject to water soaking.
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Peter Huang
PRM Industry is a highly professional Plastic, Rubber and Metal product manufacturing group. We specialize in providing our customers the integrated solutions of plastic, rubber and metal products. With more than 30 years manufacturing experience, we have been doing, and we also own the capabilities to do, is listening to what our customers need and supplying them the best solutions.
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