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LSR injection Molding VS Compression Molding

The Difference between LSR Injection Molding and Compression Molding

You may have heard many suppliers told you that the process of your customized silicone product is compression molding, LSR injection molding, silicone molding or hot pressing molding, do you really know the difference between all these different processes? If you have met this kind of problem, you should really take a look at this article, which will make you look like a more professional buyer. For better understanding, we’ve also taken an video, it takes less time for your to understand.


Since the silicone can be divided into solid silicone and liquid silicone, which effects the further silicone molding process a lot. Today, we'll mainly introduce you the difference of compression molding and LSR injection molding at first.


Compression Molding (Hot Press Molding/ Heat Molding)

The raw material of compression molding is solid silicone, which requires manual mixing for raw materials. While in mixing, the worker will add different agents, such as, coloring agent, vulcanization agent, anti-bacterial agent, the agents can be customized according to customer’s requirements, when the mixing process finished, they will cut the silicone into small pieces, according to product weight validated while in prototyping. Then the semi-finished silicone will be used for compression molding.


Usually, the mold of compression molding is 1 upper plate and 1 base plate, after weighing, the silicone will be put into the mold, press the machine, waiting for the molding process. 

For compression molding products, it usually needs to take the secondary vulcanization, i.e., baking again, to deodorize the smell and some low molecular. The molding temperature varies from 155 Celsius degrees to 165 Celsius degrees.


LSR Injection Molding

The raw material of LSR injection molding is liquid, and the liquid silicone contains agent A and agent B. If want to customize colors, there will be agent C, added separately, also, the anti-bacterial or other functional agents will be added to agent C. The agent A and agent B will be mixed by the feeding system of liquid injection machine, at the ratio of 1:1. If the ratio is not even, the silicone will not be fully heated while in molding. 

As to the process of LSR injection molding, when the worker set up the mold and machine, once press the machine, the mold will be closed, and the feeding system will shot the raw material into the mold, so to start the molding process.

Regarding to the mold structure, for vertical machine, there will be 3 plates, 1 upper plate and 2 base plates, the worker can take out the products while the other plate is in liquid injection molding. While, for horizontal machine, there will only 1 upper plate and 1 base plate. And the molding temperature will be much lower than compression molding, is about 132 Celsius degrees to 138 Celsius degrees.

Yejia silicone, as the silicone molded products manufacturer for over 13 years, we have 2 kinds of liquid silicone rubber injection machines, that is, the vertical injection machine and the horizontal injection machine, and one type of compression molding machine.

LSR injection Molding VS Compression Molding

Compression Molding MachineHorizontal LSR Injection Molding MachineVertical LSR Injection Molding Machine

If you want to know more information or if you have a customized silicone product want to find a silicone molding supplier, please feel free to contact us.