Liquid Injection Molding

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Liquid Injection Molding

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 What is Liquid Injection Molding?

  Liquid injection molding(LIM) is also known as liquid silicone rubber (LSR) injection molding or silicone injection molding, is the process of curing a non-toxic, high temperature resistant, highly flexible liquid silicone material, which the A and B components mixed in a precise 1:1 ratio to produce a chemical reaction, then cured to the final product at high temperature.

  The liquid silicone is molded with platinum as the catalyst, and the A and B components of the liquid material are cured by rapid reaction. It can be produced in a large number of repeatedly and stably by multi-cavity molds, and if some of the products are designed with color, it can be equipped with color pump sets and color metering devices with color materials.

Generally, the liquid injection molding is done at a mold temperature of 110-130°C for 150-250 seconds (the molding time will change with the thickness, size, and material of the product) to trigger a chemical reaction to cure the silicone material to form the final product.

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Advantages of Liquid Injection Molding

Liquid silicone rubber is a liquid material with high transparency, which makes it suitable for optical devices. It is also suitable for food appliances and invasive medical devices with high requirements for cleanliness, and can produce highly customized products with complex shapes. And the main advantages of liquid injection molding is as below.

1. High product precision

2. One-time molding, automated production to achieve high output

3. Saving manpower and electricity

4. No scrap

5. Operator working conditions are more concise and comfortable, therefore efficiency will be higher

Liquid Injection Molding Process

Normally, the liquid injection molding workflow is as follows.

Liquid injection molding - Deflashing - Full inspection- Post Curing - Packaging


Common Problems of Liquid Injection Molding

When the mold is empty, after the mold is closed, the air will be trapped in the mold cavity, when the injection molding starts with filling liquid silicone material, the air in the mold cavity space is firstly squeezed, due to the low viscosity of liquid silicone, the filling in the mold cavity is fast, if in this fast filling process, the air in the mold cavity is not completely discharged, or even encapsulated in the silicone, it will cause the problem of gas encapsulation (also known as trapped air, bubbles, lack of material), or there is a high pressure gas at the end of the flow causing the phenomenon of silione melted.

The most effective way to remove the air trapped in the cavity is to use cavity evacuation to forcibly remove the trapped air from the cavity during each injection molding cycle. Another method that has been successfully used is to adjust the clamping force of the mold to achieve the effect of exhausting air. When the mold is filled to 90% to 95% of the mold cavity, the mold is converted to high-pressure clamping conditions, but under low-pressure conditions, care must be taken to avoid liquid silicone from escaping to form burrs.

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To sum up liquid injection molding is a relatively unique processing technology, industry demand for liquid injection molding products also has a growing trend, new applications will also be more and more products, for over two decades, Yejia Silicone focuses on R&D& production of liquid injection molding products, we're experienced in this kind of technics, if you're looking for liquid injection molding factory, welcome to contact us.

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