Six injection molding processing technologies for home appliance plastic products
Plastic products for household appliances are mainly molded by injection molding, extrusion molding, thermoforming, hollow molding, lamination molding, compression molding, transfer molding, foam molding, casting, embedded casting, sealing casting, etc., with injection molding as the main one.
In recent years, some of the new plastic processing technology, new equipment in the molding of home appliances plastic products have been a large number of applications, such as precision injection molding, rapid prototyping technology, molten core injection molding technology, gas-assisted / water-assisted injection molding technology, electromagnetic dynamic injection molding technology and film injection molding technology, and so on.
1. Precision injection molding
It is possible to ensure high precision and repeatability of products in terms of size and weight. Injection molding machines using this technology can realize high-pressure, high-speed injection. Since its control mode is usually open or closed loop control, it can realize high-precision control of injection molding process parameters.
Usually, precision injection molding requires high precision of the mold. At present, the domestic has been able to produce small and medium-sized precision injection molding machines.
2. Rapid prototyping technology
Is accompanied by home appliances varieties to diversify the direction of development and continuous renewal and rapid development, mainly for the preparation of home appliances with plastic shell. The advantage of this technology is that it does not require molds to achieve small batch production of plastic parts.
At present, the more mature rapid prototyping methods are laser scanning molding and liquid light curing molding, of which the laser scanning molding method is more widely used. Laser scanning equipment is composed of laser light source, scanning device, powder spreading device and computer. The process is, by the computer-controlled laser head scanning according to a certain trajectory, in the position of the laser passes through, the plastic micro-powder by the heat melting and bonded together, every scanning is completed, the micro-powder device will be scattered a layer of thin powder, so that, after repeated scanning, the formation of a certain shape and size of the product.
Now, some domestic enterprises have been able to produce laser scanning molding machine and plastic micro-powder, but the performance of the equipment is not stable, micro-powder varieties of grades are also less.
3. Molten core injection molding technology
Usually used for molding the cavity roughness and high precision requirements, can not be processed by hollow molding or rotational molding methods of shaped cavity products.
At present, the application of this technology in foreign countries has been more mature, but in the domestic is still in the individual application state. The processing principle of this technology is that the first molding out of the cavity constitutes the core type, and then use the core type as an insert injection molding.
Under the heating effect of the injection molding part, the core mold melts and flows out, thus forming a cavity. The most important point in using this technology is the need to master the melting point of the core material and the molded part. Usually, the core material can be general-purpose plastics, thermoplastic elastomers or low-melting-point metals such as lead and tin, depending on the specific situation.
4. Gas-assisted/water-assisted injection molding
Wide range of uses, can mold a variety of types of injection molded parts, the typical product is the TV shell. When injection molding, gas or superheated water can be injected into the cavity almost simultaneously with the plastic melt.
At this time, the plastic melt will be covered with gas or superheated water, the molded plastic products for the sandwich structure, the molded parts can be demolded by discharging the gas or water after shaping. Such products have the advantages of material saving, small shrinkage, good appearance and good rigidity. The key part of the molding equipment is gas-assisted or water-assisted device and its control software.
In recent years, although the domestic research more, the application speed is faster, but the domestic equipment is not yet stable.
5. Electromagnetic dynamic injection molding technology
This technology causes the screw to reciprocate in the axial direction through the action of electromagnetic force. Due to the microscopic plasticization of the plastic in the preplasticization stage, the structure of the part is denser in the holding stage and the internal stresses in the part are reduced.
This technique can be used to mold more demanding products such as compact discs. When it is used to mold ordinary products, the quality of the products can be improved.
6. Film injection molding technology
When using this technology, it is necessary to clamp a special printed decorative plastic film in the mold before injection, and then injection molding. After heat deformation, the printed film can be attached to the surface of the molded part, which is not only beautiful and firm, but also eliminates the step of post-decoration.
In general, home appliances plastic products on the plastic mold demand is very large, for example, a refrigerator or a fully automatic washing machine requires plastic mold usually more than 100 pairs, an air conditioner needs more than 20 pairs of a color television set needs 50-70 pairs of plastic molds.
At the same time, the technical requirements of plastic mold is relatively high, often also requires the mold processing cycle to be as short as possible, which greatly promotes the mold design and the development of modern mold manufacturing technology. In addition, some of the more difficult molds such as hot runner injection molds, stacked injection molds, etc. in the domestic application is gradually increasing.
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