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Injection Moulding Solution
Aug 30, 2017

Injection molding, also known as injection molding, it is a injection molding method. The advantages of injection molding method is the production speed, high efficiency, the operation can be automated, color varieties, the shape can be from simple to complex, size can be large to small, and the product size is accurate, easy to replace the product, can form complex Parts, injection molding for a large number of production and shape of complex products such as molding processing.

At a certain temperature, through the screw stirring completely molten plastic material, with high pressure into the mold cavity, after cooling and curing, to get the molding method. This method is suitable for batch production of complex parts, which is one of the important processing methods.

temperature control

⒈ barrel temperature: injection molding process need to control the temperature of the barrel temperature, nozzle temperature and mold temperature. The first two kinds of temperature mainly affect the plasticization and flow of plastic, and then a temperature is mainly affecting the flow of plastic and cooling. Each plastic has a different flow temperature, the same kind of plastic, due to different sources or grades, the flow temperature and decomposition temperature is different, it is due to the average molecular weight and molecular weight distribution caused by different plastic in different types of injection Machine plastic process is different, so choose the cylinder temperature is not the same.

⒉ nozzle temperature: nozzle temperature is usually slightly lower than the maximum temperature of the barrel, which is to prevent the melt in the straight-through nozzle may occur "salivation phenomenon." The nozzle temperature can not be too low, otherwise it will cause the melt early coagulation and nozzle clogging, or because the early injection into the cavity and affect the performance of products.

⒊ mold temperature: mold temperature on the product's inherent performance and apparent quality of a great impact. The temperature of the mold depends on the presence or absence of the crystallinity of the plastic, the size and structure of the product, the performance requirements, and other process conditions (melt temperature, injection speed and injection pressure, molding cycle, etc.).

Pressure control

Pressure during the injection process, including plasticization pressure and injection pressure of two, and a direct impact on plastic plastic and product quality.

⒈ plasticization pressure: (back pressure) with screw-type injection machine, the top of the screw in the screw rotation back when the pressure is called plastic pressure, also known as back pressure. The size of this pressure can be adjusted by the relief valve in the hydraulic system. In the injection, the size of plasticizing pressure is with the screw design, product quality requirements and the type of plastic and need to change, if these conditions and the screw speed are unchanged, then increase the plasticization pressure will strengthen the shear Role, that will increase the temperature of the melt, but will reduce the efficiency of plasticization, increase the counter current and leakage, increase the driving power. In addition, increasing the plasticizing pressure often results in a uniform temperature of the melt, uniform mixing of the colorants, and removal of the gas from the melt. general

In operation, the decision to plasticize the pressure should be to ensure that the quality of products under the premise of the lower the better, the specific value is different with the use of plastic varieties, but usually rarely more than 20 kg / square centimeter.

⒉ injection pressure: in the current production, almost all of the injection machine injection pressure is the top of the plunger or screw on the plastic

The pressure applied (by the oil pressure conversion) shall prevail. The effect of injection pressure on injection molding is to overcome the flow resistance of the plastic from the cartridge to the cavity, the rate at which the melt is charged, and the melt to be compacted.

Injection molding process is a complex involving mold design, mold manufacturing, raw material properties and raw material pretreatment methods, molding process, injection molding machine operation and other factors, and with the processing environment conditions, product cooling time, post-processing process is closely related to the complex Manufacturing processes. Therefore, the quality of the product is not only depends on the quality of injection molding machine injection molding accuracy, measurement accuracy, or only by the merits of mold design and mold processing accuracy level, usually, it will be affected by the other factors and Restrictions.

In such a large number of composite factor constraints, the emergence of defects in injection molded products is inevitable, so to find the inherent mechanism of defects and predictive products may produce defects in the location and type, and used to guide the mold design and improvement, induction defects It is very important to develop a more reasonable process operating conditions. We will from the impact of injection molding process of plastic materials, mold structure, injection molding process and injection molding equipment to explain the three main factors of injection molding defects and solutions.