This document discusses six plastic processing technologies used for home appliance plastic products: 1) Precision injection molding which allows for high precision and repeatability, 2) Rapid prototyping technology which allows for small batches without a mold, 3) Melt core injection which uses a core that melts and flows out to form a cavity, 4) Gas-assisted/water-assisted injection which injects gas or water during injection for a sandwich structure, 5) Electromagnetic dynamic injection which causes axial screw reciprocation for a more compact structure, and 6) Film injection which adheres a printed film to the surface. It also notes that home appliances require many molds and that mold technologies are developing to meet technical requirements.

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Six injection molding processing technologies for plastic
products for home appliances
Translated by Jasmine HL
The molding and processing methods of plastic products for home appliances mainly include
injection molding, extrusion molding, thermoforming, hollow molding, lamination molding,
compression molding, transfer molding, foam plastic molding, casting molding, insert casting,
sealing casting, etc., among which Mainly injection molding.
In recent years, some new plastic processing technologies and new equipment have been widely
used in the molding of home appliances plastic products, such as precision injection molding,
rapid prototyping technology, melt core injection technology, gas-assisted / water-assisted
injection molding technology, electromagnetic dynamic injection molding technology, and
coatings Film injection molding technology.
Precision injection
It can guarantee the product in terms of size and weight with high precision and high
repeatability. The injection molding machine using this technology can achieve high pressure and
high-speed injection. Because its control mode is usually open-loop or closed-loop control, it can
achieve high-precision control of injection molding process parameters.
Generally, precision injection requires higher precision in the mold. At present, China has been
able to produce small and medium-sized precision injection molding machines.
2. Rapid Prototyping Technology
It is developed rapidly along with the diversification of home appliance varieties and continuous

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upgrading and is mainly used to prepare plastic housings for home appliances. The advantage of
this technology is that small batches of plastic parts can be achieved without the need for a mold.
At present, the more mature rapid prototyping methods include laser scanning molding and
liquid light-curing molding. Among them, the laser scanning molding method is widely used. The
laser scanning device is composed of a laser light source, a scanning device, a dusting device, and
a computer. The processing process is that the computer-controlled laser head scans according to
a certain trajectory. At the position where the laser passes, the plastic micro-powder is heated
and melted and bonded together. After each scan, the micropower device sprinkles a thin powder.
After repeated scanning, products with a certain shape and size are formed.
At present, some domestic enterprises can produce laser scanning molding machines and plastic
powders, but the performance of the equipment is unstable, and the types of powders are also
small.
3. Melt core injection technology
It is usually used to form special-shaped cavity products with high requirements on cavity
roughness and accuracy, which cannot be processed by hollow forming or rotary forming
methods.
At present, the application of this technology in foreign countries has been relatively mature, but
it is still in an individual application state in China. The processing principle of this technology is
that the core shape that forms the cavity is formed first, and then the core shape is used as an
insert for injection molding.
Under the heating effect of the injection molded part, the core is melted and flowed out, thereby
forming a cavity. The most important point to use this technology is to know the melting point of
core materials and plastic parts. Generally, the core material can be selected from
general-purpose plastics, thermoplastic elastomers or low-melting-point metals such as lead, tin,
and the like according to specific conditions.
4. Gas-assisted / water-assisted injection molding
It has a wide range of applications and can be used to form many types of injection molded parts.
Its typical product is a TV casing. During injection, gas or superheated water can be injected into
the cavity almost simultaneously with the plastic melt.
At this time, the plastic melt is covered with gas or superheated water, and the formed plastic
product has a sandwich structure. After the plastic part is shaped, the gas or water can be
released and the mold can be demoulded. Such products have the advantages of material saving,
small shrinkage, good appearance, and good rigidity. The key part of the molding equipment is
the gas or water-assisted device and its control software.
In recent years, although there have been many domestic studies on this and the application
speed is fast, domestic equipment is still unstable.
5. Electromagnetic dynamic injection molding technology
This technology causes the screw to reciprocate in the axial direction through the effect of the
electromagnetic force. Because the plastic is micro-plasticized in the pre-plasticizing stage, the
structure of the plastic part in the holding stage is more compact, and the internal stress of the

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product is reduced.
This technology can be used to form more demanding products such as optical discs. When used
in the molding of ordinary products, it can improve the quality of the products.
6. Film injection molding technology
When using this technology, it is necessary to clamp a special printed decorative plastic film in a
mold before injection molding, and then injection molding. The printed film can be adhered to
the surface of the plastic after being deformed by heat, which is not only beautiful and firm but
also eliminates the post-decoration step.
In general, the demand for plastic molds for home appliances plastic products is very large. For
example, a refrigerator or a fully automatic washing machine usually requires more than 100
molds, an air conditioner requires more than 20 pairs and a color TV. The machine requires 50-70
pairs of plastic molds.
At the same time, the technical requirements for plastic molds are relatively high, and the mold
processing cycle is often required to be as short as possible, thereby greatly promoting the
development of mold design and modern mold manufacturing technology. In addition, some
difficult molds such as hot runner injection molds and laminated injection molds are gradually
increasing in domestic applications.