The temperature of nozzles should not exceed 300 ℃, and the temperature of nozzles is generally lower than that of barrel temperature.Ģ. Usually, the barrel temperature is controlled at 240~280℃, and the barrel temperature of glass fiber reinforced PET is 250~290℃. If the temperature is too low, it is not good to make plastic plastic parts, depression, lack of material defects on the contrary, the temperature is too high, will cause the spill, nozzle salivation, deep color change, the decline in mechanical strength, even cause degradation. The forming temperature range of PET is narrow, and the temperature will directly affect the performance of the product. The main injection molding conditions of PET:ġ, Temperature of the barrel. The low pressure PP material must be used before starting the molding, and the barrel is cleaned. But the nozzle temperature is not too high, otherwise cause salivation. The nozzle should have heat preservation and temperature control measures to ensure that the nozzle will not be frozen and blocked. The hydraulic brake valve type nozzle is good. When the glass fiber reinforced PET is reinforced, the inner wall of the barrel is badly worn, and the barrel is made of wear-resistant material or lined with wear-resistant material.Īs the nozzle is short, the inner wall requires polishing and the aperture is as large as possible. On the other hand, the fracture of glass fiber will be more, and the mechanical properties of the fiber will be reduced. The compression ratio is too small to produce less heat, easy to plasticization and poor performance. L/D too large materials stay in the barrel for too long, excessive heat can cause degradation and affect the performance of products. It is best to choose a mutant screw with a reverse ring at the top, which has a large surface hardness and wear resistance, and the ratio of the length to diameter ratio not L/D = (15~20):1 compression is about 3:1. PET can only be molded by a optimized PET injection molding machine. Injection molding is mainly used to enhance the molding of PET. In addition, the tip of the nozzle hole is best processed as a reverse cone as shown in figure -1, so that the molten material in the flow channel and the nozzle can be cut off conveniently. In order to prevent the nozzle clogging, a higher power heater should be installed. The melting point of the enhanced PET is up to 260 ℃. The length of the nozzle hole of the injection machine should be as short as possible, and the diameter of the injection machine should be controlled around 3mm. The screw usually needs to be hardened to avoid wear after long term use. A screw type injection machine is usually used. The injection molding method is mainly used to enhance the molding of PET. If lower mold temperature is used, transparent products can be obtained by using non – filled PET materials. Special additives such as mica can be added to PET to minimize the bending deformation. The transparent products made with PET have glossiness and heat distortion temperature. The crystallinity of the material can be improved by adding a crystalline reinforcing agent. For glass fiber reinforced PET materials, bending deformation is very easy to occur at high temperature. PET has a strong hygroscopicity at high temperature. The glass conversion temperature of PET is about 165℃, and the PET heating temperature range of the material is 120~220℃. Therefore, the property of flow of melted material is changed mainly from the pressure. The rheological property of PET is better in the melting state, and the influence of pressure on the viscosity is larger than that of the temperature. At present, the most used by customers is the GF-PET, mainly for the bottle preform. PET chemical name is Polyterephthalate alcohol ester, also known as polyester. For PET for injection molding, technical personnel need to consider many factors. PET plastic injection molding process is one of the very important technology for processing plastic, PET plastic bottles, most of the plastic packaging plant will adopt blow molding production process, but the injection molding process has especially the unique processing advantages. It will help PET making factory get useful knowledge in few minutes. The content includes PET property, features, injection molding process, molding machines, process conditions, processing ways,etc. PET injection molding process is one of the very important technology for plastic processing.This blog systematically introduces PET processing by plastic injection molding machines.
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