Liquid Silicone Molding

Liquid Silicone Molding, also known as LSR Injection Molding & Liquid Silicone Rubber Molding, which is also called Liquid Silicone Rubber Injection Molding and Liquid Silicone Mold which is used to produce liquid silicone rubber seal, LSR baby products or medical & infant products by Liquid silicon injection moudling machines. Not by traditional silicone rubber compression machines using traditional production method, but by liquid silicone rubber injection mold production, which is safer, preciser & more environmentally friendly & transparent, using less manpower, and having high production efficiency compared with silicone rubber compression mold.
 

Liquid Silicone Molding Material

Liquid Silicone Rubber is relative to solid vulcanized silicone rubber, it is a liquid rubber, which has good mobility, faster vulcanization speed, safer and more environmental-friendly, can fully meet the requirements of food grade.

Liquid Silicone Rubber has excellent transparency, anti-tearing strength, resilience, anti-yellowing, thermal stability, water resistance, good air permeability, heat resistance and aging resistance and weather resistance, at the same time, moderate viscosity, easy to operate, can produce high transparency products.

Liquid Silicone Molding Machine

1. Common Compression Molding Machine

2. Horizontal LSR Injection Molding Machine, for horizontal machine, the LSR products can drop down automatically, so many automatic production will choose horizontal injection machine.

3. Vertical LSR Injection Molding Machine, usually used for two-shots molding, such as for molding combining metal & plastic parts and over-molding.

Liquid Silicone Molding Tool Structure

Liquid Silicone Molding Tool Design Points

There will be some problems when manufacturing liquid silicone mold and producing liquid silicone products. So what are the matters that we should pay attention to? In general, the structure of liquid silicone mold is similar to  thermoplastics, but there are many significant differences. Liquid Silicone Rubber Molding tend to have a lower viscosity and therefore the filling time is shorter, even at very low injection pressures. In order to avoid air entrainment, the mold must have a good exhaust device. In addition, liquid silicone does not shrink in the mold like thermoplastic compounds. They tend to experience thermal expansion, rather than the expected slight shrinkage, so that their product does not stay on the raised surface of the mold as expected. It is stuck in the large surface area of the mold cavity. So when making Liquid Silicone Mold, we should pay attention to:

1. Shrinkage Rate

Although liquid silicone rubber does not shrink in molds, it usually shrink by 2.5 to 3 after stripping from the mold and cooling. The exact shrinkage depends in part on the formulation of the compound. However, from the mold's point of view, shrinkage can be affected by several factors, including mold temperature, compound demolding temperature, pressure in the mold cavity, and subsequent compression.

The position of the injection point is also worth considering because the contraction in the direction of the compound flow is usually greater than that in the direction perpendicular to the compound. The shape of the product size also has an impact on its shrinkage, the thicker products, generally the smaller shrinkage it will be.

2. The Parting Line

The first step in the design of LSR injection mold is to determine the location of the parting line. The exhaust is mainly achieved through a groove located on the parting surface, which must be located in the area where the injected rubber finally reaches, thus avoiding the formation of bubbles and reducing the strength loss of the adhesive joint.

Due to the low viscosity of liquid silicone rubber , the parting line must be accurate to avoid overflow. Even so, boundaries can often be seen on the final product. The liquid silicone mold is affected by the product's geometry size and the position of the parting surface. A slightly chamfered product design helps to ensure that the product has a consistent affinity with the desired half chamjiuber.

Xiamen Better Silicone Rubber Co.,Ltd, not only can make rubber compression tooling & plastic injection molding, produce silicone rubber parts & products, but also can make liquid silicone rubber injection mold and produce liquid silicone products. 
Four production plants: Mold-Making Plants, Silicone Rubber Compression Plant, Plastic Injection Plant, Liquid Silicone Rubber Injection Plant.
At the beginning, our company only have basic and good CNC, EDM, Grinder, Milling machines etc. For better mold quality, we also have one imported precisely high speed CNC, two mirror EDM, one precision Grinder and related test device now. 
Compression silicon rubber molded parts tolerance, can up to +/- 0.02mm, like for medical device, smart cell phone, electronic and so on.