Silicone Parts Manufacturer
Custom manufacturer of molded silicone and rubber products including O-rings, seals, bellows, hoses and profiles. Also offers extruded and fabricated elastomeric goods to specifications. Serves aerospace, automotive, building, construction, chemical processing and electronics industries. Lean manufacturing capable.
Provides heat-resistant and dielectric silicone compounds in tubing and sheeting. Offers a wide range of color options. Also offers customization services like imprinting.
Liquid Silicone Rubber (LSR) Injection Molding
The injection molding process is the most common method used to manufacture silicone parts. Uncured liquid silicone starts in two containers (known as a kit) that connect to the pumping system: container A holds the base-forming material, and container B contains a catalyst. A metering unit dispenses these materials at a constant one-to-one ratio and mixes the mixture with pigment for color parts.
The mixed silicone material is then fed into an automated injection mold. The machine’s platens and pistons align and close the mold to ensure accurate and consistent injection pressure. It also controls the injection rate to deliver a specific shot size for the part geometry.
Unlike other plastics, LSR is crosslinked utilizing a platinum-catalyzed reaction and does not produce significant byproducts. This feature makes it useful over a broad range of temperatures.
Like injection molds for thermoplastics, LSR molds can be made from a variety of alloys and materials. However, a stainless steel mold is preferred because it supports higher injection pressures and maintains accuracy over a long production run.
Because of the curing and solidification process, a key challenge of LSR injection molding is controlling shrinkage. To reduce the risk of dimensional variations in a finished product, early quality planning, visual inspections, and testing are essential. Choosing an ISO-certified supplier with quality best practices helps to assure quality and consistency.
Liquid Silicone Rubber (LSR) Compression Molding
The liquid silicone rubber (LSR) injection molding process produces elastic parts by injecting uncured LSR into a mold cavity. This enables manufacturers to design highly complex shapes that aren’t feasible with traditional thermoplastic elastomers like TPEs. The physical properties of LSR are also outstanding – it remains flexible and resilient down to -94°F and resists the damaging effects of sunlight and ozone. Typical designs include seals, insulators, diffusers, mats and bellows.
The uncured LSR material consists of two components, Compound A and Compound B, and is fed through an automated pumping system into the heated mold. The injection settings are programmed Silicone Parts Manufacturer and customized to meet the specific needs of each customer part design. For color parts, additional pigment can be added at the time of fabrication.
Liquid silicone rubber has a lower viscosity than HCR and can be injected into thin and complex areas of the mold. It can even be overmolded onto other parts fabricated from a wide range of plastics.
The raw, uncured LSR materials are a mixture of vinyl and methyl siloxane groups that are polymerized to form long molecular chains. These chains are crosslinked to create a tough, elastic elastomer. In some cases, these elastomers are stripped of extractables to meet medical grade standards. This makes them suitable for use with human tissues.
Liquid Silicone Rubber (LSR) Insert Molding
LSR injection molding uses liquid silicone rubber as the base material that’s injected into a custom mold to create a finished product. It’s a cost-effective process that can be Silicone Supplies used to produce high volumes of parts in a short amount of time. The molds are fabricated through CNC machining to accurately capture the design of your part, making it easier for manufacturers to manufacture intricate and detailed parts that would be difficult to fabricate using other methods.
The injection molds are preheated to a specific temperature that’s appropriate for the type of silicone grade being used in the product. Once the product has been molded, it’s typically cooled in ambient conditions before it’s demolded and cured.
Silicone parts can also be overmolded with a hard material, such as plastic or metal, to make them more useful in your end application. This process is known as insert molding, and it can be performed in the same manner as overmolding with LSR or injection molding. This type of fabrication is useful for a wide range of applications, from consumer electronics to industrial equipment and safety/building technology. This manufacturing technique provides tight tolerance and strict quality control, allowing you to ensure that your finished product meets specifications, tolerance criteria and regulatory standards. It’s an ideal solution for producing medical devices that require production in a Class VII or Class VIII clean room.
Liquid Silicone Rubber (LSR) Overmolding
The overmolding process involves a completed plastic or metal entity being placed into the mold site of an LSR injection mold, after which the LSR is overmolded directly onto the part. The overmolded silicone rubber provides a product with both the rigidity and durability of the LSR and the aesthetic appearance of the finished plastic or metal part.
Overmolded silicone rubber is used in a variety of different industries. For example, medical manufacturers rely on the material’s biocompatibility, hypoallergenic and hygienic properties when manufacturing syringes or masks. Appliance and vehicle manufacturers utilize the material’s resistance to heat, oxidation and vibrations. And, consumer products benefit from the insulating properties of LSR, including blenders and toothbrushes.
This type of molding offers cost and time savings by eliminating the need for secondary post-molding assembly processes. It also gives designers greater flexibility in the design of their product, with features like thin profiles, undercuts, and micro-parts able to be more easily achieved.
When using this method of molding, it’s important to remember that the bonding of the silicone to the substrate requires a certain level of temperature and pressure. For this reason, it’s a good idea to use a PTFE mold coating and needle valve-type cold runner. This will ensure a constant temperature in the mold cavity to help the silicone adhere and cure properly.