What Are the Molding Processes for Silicone Products?

Silicone products, known for their excellent properties, are increasingly being used in various fields. The environmental friendliness, non-toxicity, odorlessness, and high-temperature resistance of silicone define its application scope. Different silicone products require different manufacturing processes, which should not be confused. How many molding processes are there for silicone products? Let me introduce them in detail:

1. 1. Compression Molding
      This is the most common manufacturing process, which primarily relies on molds. The mold’s shape determines the final shape of the silicone product. Compression molding typically involves placing solid silicone material mixed with a curing agent into a heated mold, applying pressure through a curing machine, and forming a solid product at high temperatures. The hardness of molded silicone is usually between 30°C and 70°C. This process is simple and is suitable for all types of silicone products.

   2. Injection Molding
      This process is used when high-quality standards are required, and it combines liquid silicone with plastic. The resulting products have excellent heat stability, cold resistance, electrical insulation properties, and do not emit toxic substances when burned. Therefore, this method is widely used in the production of health products, automotive parts, baby products, medical devices, diving equipment, kitchenware, and sealing components.

   3. Extrusion Molding
      Silicone products made through extrusion molding are usually formed by an extrusion machine, producing long or tube-like shapes that can be cut to any length. The products made by extrusion molding tend to have simple shapes, often in the form of strips. Silicone tubes, for example, are widely used in the medical and mechanical fields and can also serve as packaging material for buffering purposes.

 4.Calendaring
After mixing white carbon black, silicone oil, and other ingredients to create a compound, silicone rubber is calendared into sheets. The sheets produced by calendaring exhibit significant differences in physical and mechanical properties between the longitudinal and transverse directions. This is known as the “calendering effect.” Specifically, the longitudinal tensile strength is higher than the transverse strength, while the elongation at break in the transverse direction is greater than in the longitudinal direction. The longitudinal shrinkage is also greater. The degree of this effect depends on factors such as the compound composition, calendaring temperature, speed, and ratio. Calendaring is typically used for larger silicone products such as silicone sheets and silicone plates.

5.Casting or Pouring Molding
Casting or pouring molding is suitable for products with smooth or simple surfaces, and it saves time by eliminating the need for mold lines. The process involves surrounding the product or model to be replicated with a silicone sheet or glass plate, then pouring vacuum-treated silicone directly onto the product. After the silicone dries and sets, the product is removed, and the mold is formed. (Note: It is common to use softer silicone for the mold in casting, as it allows for easier demolding without damaging the product inside the silicone mold.) This process combines solid and liquid silicone and is commonly used for items like phone cases, luggage covers, and more.

6.Coating, or Fast Curing
This process involves a strong adhesive force, good flowability, and easy bubble removal. Platinum-catalyzed complexes are used, which are non-toxic and odorless. The final product has excellent thermal stability and cold resistance (operating temperatures range from -60°C to 200°C). Once formed, the product has good breathability, heat resistance, tensile strength, anti-slip properties, and low hardness, making the adhesive bonding solid and durable. It is highly resistant to tearing, transparent, and flexible. Coated silicone is also resistant to washing, high temperatures, and is known for its excellent elasticity. Common silicone products using this process include silicone gloves and rain boots.