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What's the difference between LSR injection molding and Compression molding?

Aug. 16, 2022

Difference Between LSR Injection Molding and Compression Molding

As a professional LSR injection molding manufacturer, Hopewell would like to share the difference between LSR injection molding and Compression molding. There are four four aspects in their differences. We will give your more detailed explanation.

 

Raw Material

The raw material of Compression molding is solid, and the solid silicone needs to be mixed manually. Our staff will pick raw materials from the warehouse according to the order situation, then add the corresponding agents into solid silicone while in mixing, such as: vulcanization agent (divided into: high temperature and low temperature, platinum and peroxide, etc.), coloring agent, anti-bacteria agent and so on. The agents added into solid silicone vary from different products, our engineers will validate while in prototyping, and they are also carried out according to the order situation. After mixing, the raw materials will be cut and packed for hot pressed.

The raw material of LSR injection molding is liquid, it will be mixed by the LSR injection molding machine's feeding system, and agent A and agent B to be mixed at the ratio of 1:1. For customized colors, there will be agent C to be added separately at a certain ratio, depends on different customized silicone products.

 

Difference Between LSR Injection Molding and Compression Molding   Difference Between LSR Injection Molding and Compression Molding


Solid Silicone                                                                                 Liquid Silicone

 

Process

The process of compression molding is rough as below:

Raw Materials Preparing- Compression Molding- Sampling Inspection- Deflashing- Secondary Vulcanization (Baking is for high temperature deodorization)-Full Inspection- Packing- OQC- Shipping

These processes will also be applied according to the characteristics of different products, and some products will also have the step of punching. The defective products generated in the process of compression molding are mainly caused by the following 6 factors:

  • People, the speed of each person will be different, and the speed of placing the product and taking the product will directly affect the product.

  • Machine, it is also very important for the machine to be adjusted to the appropriate parameters.

  • Material, when the weight of the raw material exceeds the positive or negative values, it will also lead to the defective product.

  • Method, the method of placing materials and taking products, improper operation will also affect the quality of the product.

  • Environment, which means that the environment within the production and operation range should be clean, and if the dirt is attached to the product, it will produce defective products.

  • Measurement, the QE must be careful when measuring.

 

Process of LSR Injection Molding

LSR Injection Molding - Sampling Inspection- Deflashing-Full Inspection- Packing- OQC- Shipping

Unlike solid raw materials, the liquid does not require manual mixing and can be directly collected from the warehouse. Liquid raw materials have different degrees and properties, and they are selected according to customer requirements or product needs. Special attention should be paid to: A and B agents work at the same time when feeding, so if one agent is short of material, it will lead to poor products, so it should be replenished in time.

The difference from the solid state is the material weight. The liquid silicone is adjusted by the machine while the solid material weight is manually weighed, and it does not need manual placement, which can reduce time thereby making it more efficient.

The liquid injection molding machine mainly produces silicone valves, silicone optics, silicone covers, medical silicone seals and other customized LSR overmolding waterproof silicone products.

 

Molding Temperature

For the compression molding, the molding temperature is controlled between 165±5℃. While for the LSR injection molding, the molding temperature is controlled between 135±3℃.

 

Mold Structure

Due to the molding machines for these two processes are different, the mold of compression molding, it is composed of 1 upper mold and 1 lower mold. As to the mold of LSR injection molding, for vertical injection machines, the mold is composed of 1 upper mold and 2 lower mold, while for horizontal injection machines, the mold is composed of 1 upper mold and 1 lower mold, but the mold of LSR injection molding are more precise than the mold of compression molding.



Difference Between LSR Injection Molding and Compression Molding       Difference Between LSR Injection Molding and Compression Molding

                                                                                           Compression Molding Machine                                                           Vertical LSR Injection Molding Machine

 


Difference Between LSR Injection Molding and Compression Molding

Horizontal LSR Injection Molding Machine

 

For better understanding, we've also taken a video for an explanation, you can click Video Center to watch it. If you still have questions on the difference between LSR injection molding and Compression molding, want to know more information or if you have a design that needs to be customize, please feel free to contact us.

Difference Between LSR Injection Molding and Compression Molding

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