The manufacturing process of silicone rubber parts includes several key steps, from material selection to molding and post-processing.
1. Material selection
- Silicone rubber material selection: Select the appropriate silicone rubber material according to the functional requirements of the part, such as hardness, temperature resistance, tear resistance, transparency, etc. Common silicone rubber materials include ordinary silicone rubber, liquid silicone rubber (LSR), high temperature vulcanized silicone rubber (HTV), etc.
2. Mixing
- Mixing silicone rubber: Mix the silicone rubber base with additives such as vulcanizers, pigments, fillers, etc. The mixing process can be completed by an open mixer or a closed mixer to ensure that the material is evenly distributed and achieves optimal performance.
3. Molding process
- Compression molding: This method is suitable for the manufacture of most silicone rubber parts. The mixed silicone rubber is placed in a mold, and then pressure and temperature are applied to vulcanize it. The advantage of compression molding is that it can produce parts with complex shapes and high precision.
- Injection molding: Especially suitable for liquid silicone rubber (LSR). Liquid silicone rubber is directly injected into the mold through an injection machine, and then vulcanized and molded in the mold. Injection molding is suitable for mass production and has high part precision.
- Extrusion molding: This method is often used to manufacture long strip parts such as silicone rubber pipes and sealing strips. Silicone rubber is extruded into a specific shape through an extruder and then vulcanized.
4. Vulcanization
- Vulcanization process: Vulcanization is a key step in silicone rubber molding. The silicone rubber molecular chains are cross-linked by heating to form a stable three-dimensional network structure, thereby obtaining the final physical and chemical properties. The vulcanization temperature is usually between 150°C and 200°C, and the time depends on the thickness and material of the part.
5. Post-processing
- Deburring: For molded or injection molded parts, it may be necessary to remove burrs to ensure the appearance quality of the parts.
- Secondary vulcanization: Some silicone rubber parts need to be secondary vulcanized after initial vulcanization to further improve their physical properties, such as tear strength and chemical resistance.
6. Inspection and quality control
- Dimension inspection: Use tools such as calipers and projectors to check whether the size of the parts meets the design requirements.
- Physical property testing: Test the hardness, tensile strength, tear resistance and other properties of silicone rubber parts to ensure that they meet product specifications.
7. Packaging and storage
- Packaging: According to the nature of the parts and customer requirements, appropriate packaging is carried out to prevent damage during transportation.
- Storage: Silicone rubber parts should be stored in a cool and dry environment, avoiding direct sunlight and high temperature environment.
