The hottest production technology of various compo

2022-10-14
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Various composite injection molding production technologies

multi component injection molding: traditional technology

multi component injection molding production provides new possibilities for plastic processing, that is, combining different materials or colors in a single molding. Production can be completed in one process without other assembly or post-processing steps outside the machine. Multi component injection molding is a fully automatic process with high flexibility, especially suitable for mass production. As early as 1961, Arburg successfully applied this technology

final formed parts can have a variety of functions and characteristics. Using this process, colored parts with high pressure resistance, heat resistance or chemical resistance can be produced. The parts that can be manufactured by Arburg allround include soft and hard material combinations, sandwiches and composite components. The parts with repeatable colors on the surface can also be manufactured by using the alternating injection molding process

the concept of multi-component injection molding covers multiple independent processes. The common point of these processes is to use two or more injection devices to inject a corresponding number of different materials into the mold at the same time, and produce the final product through a series of steps. The final parts can be used directly without subsequent treatment

according to the number of gates, it can be divided into two groups:

● using a single gate system, including sandwich and alternating injection molding processes

● the system with multiple gates can be preliminarily divided according to the core pulling and transfer process. The transfer process includes the transfer between two standard machines by the manipulator system, and the transfer in a specific multi-component machine through the rotation of the manipulator system and the mold. Mold rotation includes the rotation of the movable half mold through the rotating device, the rotation of the mold internals and the rotation around the vertical axis (gramtm process)

application advantages

advantages of multi-component injection molding

in multi-component injection molding, the components of the molded parts are completely separated. All components are visible on the surface, reflecting the appearance and function of the part. For example, keyboard buttons, switches with signs, or handles with soft areas to increase comfort. In addition to the advantage that special synthetic rubber can produce injection molded parts with multiple colors or materials in one process without other assembly or subsequent processing, the continuous improvement of molding technology can also bring sustained growth benefits. Injection molded parts are resistant to external influences (such as mechanical effects, thermal effects or chemical effects) through appropriate material combinations and high adhesion strength. The adhesion of the two-component bonding surface can be achieved by chemical bonding or mechanical connection. If chemical compatible materials are used, permanent molecular bonding can also be achieved through melting or welding processes. The types of mechanical links range from glass fibers that can be fixed on the surface to solid connection elements (such as holes and side recesses) on parts

in terms of processing technology, Arburg allround modular design can realize a relatively wide range of manufacturing processes. Including soft and hard composite parts containing TPE or LSR, sandwich or composite parts, or surface colors manufactured by alternating injection molding process. "Andre Heim, who was invited to attend the meeting in China recently, said that color repeatable parts

two component injection molding

the fully automatic two-component injection molding mold has two-stop, and the production of the parts is completed through another injection stage after the pre injection of the formed parts. Prefabricated parts are produced in the first cavity. Then the mold is opened, and the whole movable half mold is rotated 180 °, rotating the prefabricated cavity to the final injection position. Then, by adding the second material, the prefabricated parts are manufactured into the final parts. The mold cavity can rotate in the same direction or alternatively in different ways. After the final part is demoulded, the empty cavity can be prefabricated for the next time

three station mold for synchronously demoulding injection molded parts

in order to make the demoulding of parts independent of the production process, a demoulding station is integrated into two-component molding. Then, the mold rotates clockwise in 120 ° steps. There is an opening on the side of the third station, from which the gripper of the manipulator system can extend into the closed mold, demould the parts and their gates, and place them on the conveyor belt for further processing. Arburg's patented molding technology can simultaneously manufacture and remove molded parts, greatly shortening the cycle time, thereby improving production capacity

injection molding of more than three components

the molding process of more than three components can be realized by many methods. Here are two possible methods

two station mold

the setting method of the two station mold can be similar to the setting method of the three component mold mentioned above. In the first process step, three or more (up to five) components are simultaneously injected to produce prefabricated parts. Then, the whole half mold rotates 180 ° and moves to the second position. At this time, other materials are used to inject and seal the prefabricated parts to produce the final parts

another method is that in the mold with corresponding configuration, the parts can be combined with up to five surface elements composed of other materials/colors in one production step. Therefore, the inserts in the mold can rotate between the three stations through the rotating template and the electrically driven rotating device. Station 1 injects all cavities through hot runner and needle valve nozzle. Station 2 performs up to 5 injection molding processes on a specified number of cavities. Then, the third station can be used to demould the part from the closed mold. During the production process, the parts are demoulded, which greatly shortens the overall cycle time, and further improves the production capacity of multi-component injection molding

four station mold

for example, multi-layer plastic parts can be produced using four station mold

when using recycled materials and barrier layers, this method is easy to achieve. The schematic diagram describes the forming steps of a four layer formed part. The innermost layer is produced in the first station. Then, the mold rotates 90 ° to the next station. At this time, the first component is encapsulated by injection molding of the second component. Then, the semi mold continues to rotate to the third station, and finally to the fourth station for the final stage of production

at this time, the protective outer layer or the surface layer of the molded part is injected on the part. After the cooling phase, the final multilayer part is demoulded from the cavity. In the continuous cycle, each time the mold is opened, a final formed part will be produced

places that need to be corrected and updated alternate injection molding

alternate injection molding alternately inject the same plastic component of two different colors into the same cavity

before entering the mold, both colors are placed in a special mixing nozzle. Two color components are mixed to form a color effect. The two colors can be mixed and configured purposefully

in the alternating injection molding process, the two injection molding devices are connected together by a special alternating injection molding device (including a mixing nozzle). The device is installed on the fixed installation template of the machine, so it is in front of the mold. Factors that affect the final color include: cycle sequence, design of formed parts, location of gates, and flow characteristics of materials

in addition to the injection rate, injection molding or alternate injection molding is also one of the decisive parameters. There is a special alternating injection molding program in selogica controller, which manages the cycle sequence and material control. As long as an important index for controlling product quality and studying friction and wear mechanism is removed, except for the alternating injection molding device, the same machine can be used for two-component injection molding

sandwich injection molding

sandwich injection molding process injects a core material into the outer surface layer. The process is carried out in two or three steps in a mold cavity. First, inject the material on the surface of the stroke into the cavity. Then, the core component is injected into its internal center through the first material. Finally, seal the gate with the first component. In this way, the core material can be prevented from appearing on the surface, and at the same time, the second component in the gate system can be removed for the next injection of the first component

common applications are that molded parts need a bright appearance, while the core needs recycled materials, or technical parts need a hard core, and the surface needs to be improved to get a better feel. It can also produce molded parts with fashionable characteristics (such as colored cores with transparent surface)

composite injection molding and core fallback process

in the core fallback production process, the hollow part of the mold is closed first, and then reopened with a sliding shaft core or slider in the cycle. In the production of parts containing two components, the first injection stage is to inject the prefabricated components first, and then open the second hollow part in the same cavity (such as by dragging the sliding shaft core). Finally, the second component is injected into the prefabricated parts, so that the complete parts are produced, and then the final parts are taken out of the mold. During injection molding, you can also rotate the template to open the cavity, and then inject the second component into the first component

if there are two or more components, composite injection molding can be used, but with the increase of the number of components, the complexity of the mold will increase sharply. Since all the required actions can be completed in the mold, there is no need for any external machine accessories. However, the machine must have a sufficient number of programmable shaft cores for controlling the slider

if only one mold is needed to complete the production, and there is no need to open the mold in the middle, and there is no need to transfer prefabricated parts, composite injection molding has significant advantages. However, compared with multi-component injection molding, this production method is carried out in a strict phase sequence rather than parallel operation

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