The difference between low-pressure injection molding and traditional technology

author: Universe plastic

2024-03-18

What is low pressure injection molding

Low-pressure injection molding (LPM) is an injection molding method that injects low-pressure injection molding materials into the mold at a very low injection pressure (0.15-4MPa) and solidifies quickly (5-50 seconds).

Low-pressure injection molding generally does not inject a separate product, but uses another part as an insert, and then injection molds it. Finally, the insert is wrapped in plastic or combined to form an integrated combined part.

The most obvious difference between low-pressure injection molding and traditional injection molding is the low injection pressure. The advantage of low injection pressure is that it is not easy to damage the wrapped or combined parts.

Comparison between low-pressure injection molding process and traditional potting process:

1. The curing mechanism of the traditional potting process is a chemical reaction, while the curing mechanism of the low-pressure injection molding process is a physical reaction. The excess materials and waste can be recycled.

2. The traditional potting process requires a process cycle of about 24 hours. The process cycle of low-pressure injection molding can be reduced to a few seconds to tens of seconds, which greatly improves production efficiency.

3. The traditional potting process requires a shell made of engineering plastic, while the low-pressure injection molding process does not require pre-preparation of the plastic shell. Instead, the encapsulated shell is integrally formed during the injection molding process, which is small in size and low in cost.

4. The traditional potting process requires precise control of the 2K component ratio, and the entire process is cumbersome, while the low-pressure injection molding process only uses one kind of rubber material, has fewer process flows, is simple, and has strong mass production.

5. The traditional potting process takes a long time to cure, so it requires more brackets to store samples and takes up more production space. However, products using the low-pressure injection molding process do not require additional curing and waiting before entering the packaging process. Requires a rack for curing and takes up little production space.

6. The traditional potting process requires more packaging materials, while the low-pressure injection molding process can reduce the use of packaging materials through the design of the cavity, and even achieve partial packaging.

Advantages of low-pressure injection molding process compared to traditional coating process:

Low-pressure injection molding integrates the skin material with the plastic base material, with high bonding strength and low risk of falling off;

Since there is no glue coating process necessary for the coating process, the low-pressure injection molding process is more environmentally friendly, can effectively improve the VOC volatilization and odor of parts, and improve the air quality in the car;

The internal structure of low-pressure double-layer injection molded parts can be designed arbitrarily. Compared with the coating process, the degree of freedom in surface modeling is greater, and the modeling features are clearer and tougher, with good feel and appearance;

Low-pressure injection molding does not require additional secondary coating, has fewer processes, and improves production efficiency and yield rate;

Disadvantages of low-pressure injection molding process:

The design requirements for the mold are relatively high and the materials are relatively expensive;

It is not suitable for appearance products. The appearance of low injection molding pressure is not as beautiful as that of high pressure; The hardness of the products produced is not suitable for structural parts.

Summary

1. The purpose of designing low-pressure injection molding is not to directly replace traditional engineering plastics. For example: if a component (such as a connector) can be successfully molded with PVC, there is no need to consider using low-pressure injection molding. If PVC injection molding has a high scrap rate due to high pressure, low-pressure injection molding may be more economical because it produces less scrap.

2. Low-pressure injection molding is generally used to replace multi-step production operations, such as epoxy potting after plastic shell molding. Simple steps are often achieved using low-pressure injection molding. When a component is molded using low-pressure injection molding, an additional plastic housing is usually not required.

3. Limitations of the low-pressure injection molding process: Due to the high cost of hot melt adhesive used in low-pressure injection molding, the low-pressure injection molding process is mainly used for the packaging and protection of smaller precision components, and for larger components , it cannot reflect its economy.

Universe Plastic is a professional low-pressure injection molding factory. If you have project needs, you can consult at any time to get an injection molding quote.

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