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Advantages of injection molding process for automotive plastic parts in China

the special appearance and size requirements for injection molded parts of complex automotive parts have raised the development threshold and risk of automotive injection molded parts. Moldflow 3D software helps enterprises analyze the molding feasibility of plastic parts in the product design stage, evaluate and optimize product design through the analysis of part deformation and molding process, and guide downstream manufacturers' mold and injection molding optimization

due to the unique particularity of the plastic parts of complex automobile parts, the following factors should be fully considered in the design of injection molding. 2. The problem of the experimental journey, the drying treatment of materials, the new requirements of glass fiber reinforced materials for screws, the driving form and the clamping structure

first of all, when the commonly used resin materials such as automobile bumpers and instrument panels are modified resins such as modified PP and modified ABS, the resin materials have different hygroscopicity. In order to meet the requirements of moisture content during molding (generally ≤ 0.2%), the competition among e-commerce platforms is very fierce at present. The resin raw materials must undergo hot air drying or dehumidification drying before entering the screw pre molding measurement of the injection molding machine

the hygroscopicity of modified PP (PP EPDM) resin is small. Generally, the hot air dryer can be used at ℃ for H. Modified ABS (PC ABS) has strong hygroscopicity. Before molding and drying, dehumidification dryer shall be used for dehumidification and drying. We have fully considered the application of dehumidification and drying system in the design of automobile complex plastic parts forming system

second, at present, the domestic automotive plastic parts are basically non glass fiber reinforced plastic products. Compared with the resin containing chopped glass fiber reinforcement, the material and structure of the screw of the injection molding machine used to form non glass fiber reinforced plastic parts are quite different. When designing the injection molding machine, attention should be paid to the alloy material of the screw barrel and the special heat treatment process to ensure its corrosion resistance and strength

third, due to the difference between automobile parts and conventional products, its cavity surface is very complex, with unequal stress and uneven stress distribution. In the design, the processing capacity required by it is mainly considered. The processing capacity of the injection molding machine is reflected in two aspects: clamping force and injection molding capacity (expressed by the maximum theoretical injection volume). When the injection molding machine is molding products, the clamping force must be greater than the opening force generated by the mold cavity pressure, otherwise the parting surface of the mold will be separated and overflow will occur

the formula for determining the clamping force of the injection molding machine is as follows: P clamping ≥ P cavity × F/100。 Where: P clamping is the clamping force (or clamping force) kN of the injection molding machine; The P-shaped cavity is the average pressure of the mold cavity, MPa, which is related to the product structure shape, accuracy requirements and the number of cavities per mold. The value range is generally between MPa; F is the horizontal overlapping projected area cm3 of the mold cavity, sprue and feed inlet

to further improve the manufacturing technology level and overall strength, ensure reliable mold locking, and the process mold locking force during injection molding must be less than the rated mold locking force of the injection molding machine. The maximum theoretical injection volume of the injection molding machine matches the clamping force tonnage of the injection molding machine, which is the nominal injection volume of the injection molding machine with polystyrene (PS) as the benchmark resin before leaving the factory

fourth, according to the characteristics of the complex plastic parts of the automobile, the driving form of the injection molding machine and the design of the clamping mechanism are designed. At present, the hydraulic elbow of the hydraulic mechanical type or the full hydraulic type, or the injection molding machine of the central direct pressing clamping mechanism is widely used in China. After years of efforts, Tairui Machinery Co., Ltd. has broken through the traditional constraints and developed a mechanical structure in the form of two plate mold clamping, direct pressing and composite mold locking. The advantage of this structure lies in that its mold opening stroke is much larger than that of the hydraulic elbow mold closing structure, which is at least 2 times more than that of the hydraulic elbow mold closing structure. It can meet the production requirements of large plastic parts (such as bumpers, instrument panels, etc.) of automobiles. Secondly, four compound oil cylinders are used to lock the mold synchronously, and a small flow is used to realize the stable mold locking of large tonnage. The mold locking force can be higher than the hydraulic elbow clamping structure of the same tonnage. The precision of forming composite surface of large and complex plastic parts of automobile is fully guaranteed

fifth, as the cavity surface of automobile parts is very complex, the particularity of the injection molding machine should be considered in the design, and some special function programs should be configured, such as multi group core pulling function, timing control function, supporting mold changing device function of the injection molding machine, supporting part taking manipulator device function, etc. These special functions have obvious advantages in the production of automotive plastic parts. For example, in order to shorten the production cycle in the bumper production process with this model of injection molding machine, the large plastic products are automatically taken out by the part taking manipulator after the mold is opened and ejected, and multiple groups of core pulling are used to make the large plastic products eject smoothly and integrally, without top whitening or cracking. At present, most of the robots we use in this injection molding system are 3-axis piece taking robots ", and some use 6-axis piece taking robots

advantages of automotive plastic parts

advantages of complex automotive plastic parts:

1. Plastic can be processed and formed at one time, with short processing time and guaranteed accuracy

2. The elastic deformation characteristics of plastic products can absorb a large amount of collision energy, have a great buffer effect on strong impact, and protect vehicles and passengers. Plasticized dashboard and steering wheel are used in modern cars to enhance the cushioning effect. The front and rear bumpers and body trim strips are made of plastic materials to reduce the impact of objects outside the vehicle on the body. The plastic also has the function of absorbing and attenuating vibration and noise, which can improve the ride comfort

3. The plastic has strong corrosion resistance and will not corrode if damaged locally

4. Plastics with required properties are prepared by adding different fillers, plasticizers and hardeners to meet the application requirements of different parts on the vehicle. What is more convenient is that the plastic color can be adjusted to different colors through additives, which saves the trouble of painting. Some plastic parts can also be electroplated

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