Silicone Compression Molding
Silicone Compression Molding
Silicone compression molding is the most mature & easy-to-control production process in the silicone rubber industry. In simple terms, silicone rubber raw materials are cured into finished medical silicone parts at high temperatures and high pressure in a metal mold. Compared with injection molding, it does not need the main runner, runner, and gate system, and the mold cost is lower during compression molding. It does not require too complicated operation steps.
LSR INJECTION values the interests of customers. We recommend this molding method to customers with small and medium batch production needs, which is a very cost-effective means of silicone molding.
Advantages
If you choose this process, you get low-cost, quick-build molds, flexible and modifiable silicone part prototypes, and the same silicone raw materials as injection molding. Even with a limited budget, the performance, dimensional error, production efficiency, and other parameters of the silicone finished product can reach a satisfactory level.
The preferred process for prototyping
More controllable quality
Lower manufacturing cost
Complex parts available
Preliminary Preparation
Silicone compression molding is divided into three parts: pre-design, prototype manufacturing and compression molding. Among them, pre-design and prototype manufacturing are important basic work before compression molding.
Silicone Product Design
When you want to create a silicone product with commercial value, you need to consider both product ideas and industrial requirements. This is the premise of silicone compression molding.
Our product designers use CAD and other software to build product models required by customers, and present customers’ creative ideas in a visual form.
Not only that, we must take the most detailed consideration for the material selection, color matching, Shore hardness, size, tolerance, molding method, shrinkage rate, etc. of this product. We have experienced engineers who can advise you on professional materials and production details. This is an important part of our silicone rubber custom service.
Silicone Prototyping
The factory makes appropriate adjustments to the shape and size of the silicone rubber feedstock mix based on the structure of the final product part. The purpose of this is to better match the raw material and mold to ensure correct molding. It can effectively avoid the situation that the finished product is too thick or hollow. We call this prefab processing.
Typically, this process requires building the corresponding mold first, and an aluminum compression mold prototype takes about 1-2 weeks to make. After the production is completed, our experienced engineers will perform precision testing and calibration on the mold to ensure that the mold can meet the production requirements.
Compression molds can be used repeatedly and serve the production of corresponding silicone products for a long time.
Production Process
Kneading
- Manual mixing (HCR, LSR)
- Metering Mixing Pump (LSR)
- Small planetary gear mixer (HCR or LSR, optional)
Filling
- Manually filling the cavity
- Solid Fill (HCR, LSR)
- Cartridge Fill (LSR)
Molding
- Mold vulcanization at high temperature and pressure
- Automatic push mold clamping
- Cooling and demolding
- Use a cooling template and an ice-cooled mold to open the mold and take out the silicone parts
Trimming
- Manual and frozen flash removal (the mold can be designed with tearable flash as required)
LSR INJECTION performs a standardized silicone molding production process. We place unvulcanized silicone rubber material into a mold cavity, where the material is subjected to pressure to change its properties. After that, we pass the closed high-temperature treatment to achieve the purpose of curing.
The press machine in the workshop monitors the temperature, pressure, and compression time in real time. Through these important parameters, we can control the tolerance of the product within the specified range. For non-thermoplastic silicone materials, we add vulcanizing agents to help improve physical and chemical performance.
The carbon-hydrogen bonds in the silica gel and the sulfur in the vulcanizing agent are interconnected to form a three-dimensional network structure, which is more stable than unvulcanized silicone rubber. Product cure cycles are mostly in the 30 seconds to 2-minute range, depending on the cross-sectional area and size of the product.
Finally, the solidified LSR product will be cooled at room temperature, and technicians will use a combination of computer and manual methods to check the quality of the product. It includes post-molding processes such as deburring and post-curing.
Do you have a project for silicone products to discuss? Contact us today for a free quote!
Medical Applications
The silicone compression molding process is mostly used to manufacture parts of machinery and equipment that have strict requirements on elongation, bending, tensile and tear properties. Especially in the field of medical products has a wide range of applications.
Custom-molded silicone products include
- Silicone rubber parts for medical devices
- Medical Silicone Products
- Medical silicone tube
- Personal Care Silicone Products
LSR INJECTION Silicone Compression Molding Service
LSR INJECTION Silicone is the source manufacturer of many silicone product retail companies around the world. We have extensive experience in OEM and ODM of silicone rubber products, and can carry out silicone rubber molding production with high efficiency and high quality, ensuring that the quality of each silicone rubber part meets the industry’s first-class standards.
We have a large number of complete molding press production lines and in-house mold workshops. And we focus on providing customers with customized silicone product design and production services.
Contact LSR INJECTION today for the most competitive quote.
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Compression Molding Related Content
Silicone Materials
- Fumed Silicone Rubber
- Better tear strength, tear strength, and elongation.
- The appearance is transparent, and its environmental protection index is also high.
- The raw material is silicon dioxide obtained by burning silicon tetrachloride and air, and the fineness is over 1000 mesh.
- Silica produced by fumed silica is expensive and not easy to absorb moisture.
- Precipitated Silicone Rubber
- The precipitation method uses sodium silicate to add sulfuric acid to precipitate silica. The fineness is only 300-400 mesh.
- Low price and mature technology.
Liquid Silicone Rubber
LSR (Liquid Silicone Rubber) is a silicone-based elastomer with excellent physical and chemical properties. Compared with thermoplastic elastomers, its chemical bonds are more stable and have an irreplaceable role in some scenarios.
Most plastics melt when they reach +250°C, but LSR can withstand this temperature and work properly for a long time, even at low temperatures of -65°C, without adversely affecting its performance.
LSR is resistant to extreme temperatures, stretch resistance, long service life, waterproof, anti-ultraviolet, anti-ozone, anti-atmospheric aging, non-toxic, odorless, colorless, good light transmittance, and good resistance to deformation. LSR can maintain the stability of its own characteristics in most environments. After curing, it will not shrink back. LSR has a very high plasticity, you can add other materials to change its hardness and color according to your needs. The excellent biocompatibility of LSR makes it widely used as a raw material for products in the medical and food industries. It is recognized by the FDA as a material for long-term implantation in the human body.
High Consistency Silicone Rubber
High consistency silicone rubber (HCR) is the main raw material for the silicone compression molding process. It is also called heat-cured rubber or solid silicone rubber and is a transparent elastomeric material. It is necessary to add a sulfur-containing curing agent during molding to speed up the molding time. The feeding method is to open the mold and feed the molding. Generally used for daily necessities, industrial parts, waterproof sealing of electronic products, auto parts, etc. It can be divided into two different production processes: gas phase method and precipitation method.
