PET Preform Mould With Gloss And Thermal Distortion
PET Preform Mould injection molding process is a very important plastic processing technology is one of the PET plastic bottles, the majority of cases, plastic packaging plant will be used to blow molding the way the production process, but the injection molding process is particularly unique Processing advantages, for PET Preform Mould injection molding, the technical staff need to consider many factors, as follows.
PET Preform Mould PET plastic Description: PET chemical called polyethylene terephthalate, also known as polyester. Currently used in the customer is the most GF-PET, mainly to brew the embryo. PET has good rheological properties in the molten state, and the effect of pressure on the viscosity is greater than the temperature. Therefore, the flowability of the melt is mainly changed from the pressure.
PET chemical and physical properties: PET glass transition temperature of 165 ℃, the material crystallization temperature range is 120 ~ 220 ℃. PET has a strong hygroscopicity at high temperatures. For glass fiber reinforced PET materials, bending deformation is very prone at high temperatures. The degree of crystallization of the material can be increased by the addition of a crystallization enhancer. Transparent products processed with PET have gloss and thermal distortion. Special additives such as mica can be added to PET to minimize bending deformation. If a lower mold temperature is used, transparent products can also be obtained using non-filled PET materials.
Injection molding process: injection molding method is mainly used to enhance the molding of PET. Usually using screw-type injection machine. Screws are generally required to be hardened to avoid abrasion after prolonged use. The length of the injection nozzle hole should be as short as possible, its diameter should be controlled at about 3mm. Enhance the melting point of PET up to 260 ℃, in order to prevent nozzle clogging, should install a larger power heater. In addition, the tip of the nozzle hole is preferably machined into an inverted cone as shown in Fig. 1 so that the molten material in the flow path and the nozzle can be easily cut off.
Injection molding machine: injection molding is mainly used to enhance the molding of PET. PET under normal circumstances can only use screw-type injection molding machine. It is best to use the top of the mutant screw with a reverse ring, the surface hardness and wear resistance, length and diameter ratio is not L / D = (15 ~ 20): 1 compression ratio of about 3: 1. L / D too much material in the barrel to stay too long, excessive heat easily lead to degradation, affecting product performance. Compression ratio is too small shear heat less, easy to plastic poor, poor product performance. The other will make the glass fiber more broken, mechanical properties decline. Processing of glass fiber reinforced PET, the barrel wall wear more powerful, the use of wear-resistant materials such as manufacturing or lining with wear-resistant materials. The nozzle is short as well, the inner wall requires polish, the aperture is as large as possible. It is better to use hydraulic brake valve type nozzle. The nozzle should be kept warm and the temperature is controlled to ensure that the nozzle does not freeze. But the nozzle temperature can not be too high, otherwise cause salivation. Before the start of molding must use low-pressure PP material, the barrel clean.