Throughout the preform process equipment, in addition to injection molding machines, further comprising: a hot runner mold, polyester pellets dehumidifying dryer, mold cooling ice machines, bottle embryo out robot arm, conveyor and preform injection environment controlled air dehumidifier, and each is to tie all equipment injection molding machine actuation, the injection molding machine preform molding process plays the most important role. PET preforms are available in addition to the extrusion process, the majority are produced by injection molding preforms. PET preform injection molding process conditions It is completed by the two-stage injection molding machines and blow molding machine two machines. First by the injection molding machine into a preform after the preform is cooled to freezing temperatures Tuomo removed, cooled to room temperature, to be blowing, the blow molding machine and then sent to the preform is heated to a temperature of blowing and blowing, cooling molding.ĥ. One-piece is shot and blow in the same machine is completed, injection molded preform is cooled to below the crystallization temperature range, but remains in a state of thermo-elastic, and finally blowing into bottles.
One-piece and two-stage is divided into two kinds.
PET grain dryer use high temperature air is dehumidified, circulation in the hopper. Dry air, the dew point temperature must be between -29 ℃ and -40 ℃. Temperature of the dryer was set at between 177 ℃ and 182 ℃, dried for about four hours.įirst, injection molding processing system to a preform , which is fired into the mold cavity to melt, and then rapidly cooling, the preform temperature below the crystallization temperature range, made of transparent preform a second step of the preform is heated, it is higher than the glass transition temperature, and then extended, blow molding and cooling. Before preform injection molding, PET grain must be dried to a moisture content of 0.05% or less, so that it can create a good non-crystalline transparent preform. PET is a hygroscopic material, if the moisture content is too high, will produce at a high temperature hydrolysis process, the PET molecular chains and thermal decomposition of acetaldehyde, reduce physical and mechanical properties, the crystallization rate of speed, when the Preform Injection, will Preform partially crystalline bleaching, affecting the quality of the product. PET is a polymer, the most important feature is its molecular weight, molecular weight is the number of uniform molecular PET molecular chains, the number of molecules of longer chain link, the better the physical properties of PET. PET is a crystalline resin, a specific gravity of about 1.4, a melting point of 245 ℃, the molding temperature between about 290 ~ 315 ℃. Usually used in the manufacture of PET plastic container grain, must pay attention to the following features: (1) molecular weight (2) acetaldehyde content (3) the content of diethylene glycol (4) a carboxyl group (5) the percentage of total polymer ( 6) Melting point (7) a glass transition point (8) the degree of crystallinity. Polyethylene terephthalate (of PET) , having the features: (1) excellent in gas barrier properties (2) pressure resistance, creep resistance (3) Impact resistance (4) transparency, surface gloss (5) itself is odorless and Paul fragrance security (6) on food hygiene, and beautiful, easy molding, has been widely used in food containers. Here are some notes for the PET preform injection molding process, for all my friend, much know-how experience, much near to the perfect production. The final result is that the bad quality &bad production of PET preform in the customer factory, which will waste the money &energy &time of all. And in order to reduce the sell cost, many manufacturers also present the general purpose injection molding machine with C type of screw &big shot weight, while they obviously ignored to bring the important notes to the customer before they make a decision focus on the PET PREFORM PRODUCTION. Many friends would like to adopt the general purpose injection molding machie to produce the PET preform.
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