I. Compression Injection Molding
Compression molding is an advanced form of traditional injection molding.
Advantages: It can increase the flow length ratio of injection molded parts; use less clamping force and injection pressure; reduce material internal stress; and improve processing productivity.
Injection compression molding is suitable for making products from various thermoplastic engineering plastics, such as large curved parts, thin-walled parts, miniaturized parts, optical lenses, and parts with good impact resistance requirements.
Application examples:
As is well known, optical lenses have very high requirements for geometric accuracy, requiring both precise dimensions and minimal deformation, which is difficult to achieve with conventional injection molding.
II. Exhaust Injection Molding
Venting injection molding: The purpose of the "venting" process is to allow volatile fission products generated during polymerization-solidification to escape. If these gases cannot escape from the mold cavity, the result will be incomplete products or air bubbles at the closure points.
Sequence: 1. When the injection volume reaches approximately 80%-95%, stop the injection process;
2. Open the mold by approximately 0.1-0.2 mm to allow volatile gases to escape;
3. Close the mold again and inject the remaining amount of plastic.
Application examples:
Product: Filter plates for filter presses, 1500x1500 mm
Number of holes: 1 out of 1
Raw material: PP + 6% (flow index 0.2, high viscosity)
Injection molding machine: BU4000 with 6800T storage tank
Molding process: Compression injection molding
III. Low-pressure injection molding
Low-pressure injection molding is a packaging process that uses very low injection pressure to inject hot-melt material into a mold and quickly solidify it. It utilizes the excellent sealing properties and superior physical and chemical properties of hot-melt material to achieve insulation, temperature resistance, impact resistance, vibration reduction, moisture protection, waterproofing, dustproofing, and chemical corrosion resistance, thus providing good protection for electronic components.
IV. Gas-assisted injection molding
GAIM process:
Injection stage (partial) - Gas inflation stage (N2) - Gas holding stage (cooling pressure unchanged) - Pressure reduction stage - Demolding stage
GAIM device components:
Gas pressure generator, gas control unit, gas injection device, gas recovery device
V. Water-assisted injection molding
Water-assisted injection molding technology is an advanced injection molding process in which a portion of the melt is injected into the mold cavity, and then high-pressure water is injected into the melt through equipment to ultimately shape the workpiece.
Due to the incompressibility of water, a solid interface is formed at the water front, compressing the inner wall of the product into a cavity. The water front also provides rapid cooling. Therefore, water-assisted cooling has many advantages that air-assisted cooling cannot match. Research and applications show that water-assisted cooling can generate thinner and more uniform cavity walls, and the inner surface of the flow channel is very smooth. Especially for thick-walled workpieces, water-assisted cooling can significantly reduce cooling time compared to air-assisted cooling.
VI. High-gloss injection molding:
The basic process of high-gloss injection molding is as follows: before injection molding, the surface of the mold is rapidly heated by high-temperature and high-pressure steam, so that the surface temperature of the molding cavity reaches above the glass transition temperature (Tg) of the resin plastic. Then, the plasticized plastic melt is injected into the closed mold cavity. During the injection stage, the mold temperature remains constant due to the high-temperature and high-pressure steam. When the injection is finished, the air supply is stopped, and the steam in the air pipe is blown out by air pressure. Then, cooling water is introduced to rapidly reduce the mold temperature until it is cooled, the mold is opened, and the product is removed.
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