When choosing a silicone rubber manufacturer, you should consider many factors before deciding on a supplier. The exact dimensions and complexity of the part help depict which method of production is most efficient. Other factors that need to be considered are the volume of parts per order and how long the part will be in production. With these factors in mind, you need to consider whether liquid silicone injection molding or compression molding is right for you. Liquid injection molding tends to be the preferred method of production for most silicone rubber needs.
Compression Molding
Compression molding is a process that uses a heat-cured, weighed-out piece of silicone rubber. The silicone is pre-catalyzed by adding a powder and pigment is added to the silicone by using a two-mill roll. Once the material is all mixed together, it gets formed into pieces that are cut up to the desired weight for the part that will be molded. The rubber is then placed into a heated mold and pressed to allow the silicone elastomer to melt and fill the mold cavity. Compression molding is an open-air labor-intensive process. This means that there is a chance that contaminants may get into the parts or that fillers may be added to lower the cost of material for the manufacturer. At SiTECH, we do not use the compression molding process.
Liquid Silicone Injection Molding
Liquid silicone injection molding is a process that uses a binary liquid silicone rubber that is supplied in a closed system. A closed automated system means that the raw silicone is sealed, as well as any pigment that may be added. The reason this is important is to avoid contamination from dirt and debris that can cause problems in the production process and produce inferior parts. The raw silicone rubber is contained in two parts, with one containing a platinum-based catalyst and the other containing an inhibitor to prolong the working life of the material. These materials are connected to a dispensing machine that seals the material and uses pressure to pump the material from the original containers into the injection machine. Silicone pigment in liquid form is sealed under pressure and precisely metered into the silicone at this point to achieve the exact color needed. Once mixed, the material is housed in a water-cooled barrel to avoid catalyzation.
Comparing the Two
Silicone rubber injection molding allows for a fully enclosed, semi-automated system, which impedes any debris or contaminates from entering the process. Injection molding allows for short cycle times that fill high volume orders more efficiently. The ability to operate at lower injection pressure because of the viscosity of liquid silicone rubber (LSR) materials, means little to no variation, tighter tolerances and consistent quality. These factors make liquid silicone injection molding inherently clean and efficient over other methods of molding.
Our facility in Newport News, Virginia, provides you with a competitive domestic manufacturer of liquid silicone injection molding products. At Si-TECH, we are a U.S. manufacturer that uses the latest in technology and silicone injection molding machinery to produce the highest quality silicone rubber products the industry can offer. We use both vertical and horizontal molding machines, an advanced quality control system, and offer decorating and coating. Contact Si-Tech for any of your silicone rubber needs.
