Silicone Overmolding
Silicone Overmolding Process
Some areas are accustomed to calling it LSR 2-Shot, twin shot, assembly injection molding, or in-mold assembly. Essentially, the liquid silicone rubber overmolding process refers to the molding of silicone rubber onto a non-silicone rubber substrate. This process adds a step to placing the substrate part in the mold cavity on the basis of traditional molding. Either compression molding or injection molding can be combined with overmolding to produce complex multi-substrate silicone components.
What are the advantages?
The process focuses on overmolding the LSR into the thermoplastic substrate in the same mold and using the same machine after the thermoplastic substrate has been formed. The overmolding process is very useful because it allows you to add materials, parts and multiple functions in a single component. They are permanently fused to provide better, more cohesive results.
Best of all, because you have a two-part silicone rubber molding system, you also get the best properties of both materials. You can eliminate the need for post-molding assembly operations. Initial investment is reduced because you only need one tool to create components. The cost of inspection and qualification of the tool has also been reduced, which is something to consider. Since the process involves only one machine cycle, it’s actually quite efficient, and it allows you to focus on delivering the best possible quality and experience while delivering stunning results and a very well-rounded experience.
Wide range of applications
Save cost and time
High design flexibility
Production Process
Silicone overmolding is a layered process. The bond between the cladding and the substrate requires chemical or mechanical bond strength. We do it with mechanical undercuts, protrusions, or indentations, which prevent parts from popping out of the mold and can help silicone bond to non-silicon materials.
Molding steps
- Place the finished molded thermoplastic part, metal, or another specialty substrate into the mold cavity(or inject the thermoplastic substrate raw material).
- When the mold is closed, inject LSR(If the raw material is injected in the first step, rotate the mold first and then perform this step).
- LSR completely fills the cavity and covers the substrate.
- Complete the molding.
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Substrates for Silicone Overmolding
In terms of molding substrates, this process allows you to have more ideas and choices, and you can match multiple same or different substrates with each other.
Typically, widely used prefabricated substrate components include non-toxic thermoplastic and metallic materials. Adding a substrate part helps you change the appearance and hardness of your silicone product as desired. Correspondingly, silicone overmolding can provide effects such as waterproofing, insulation, shock resistance, and sealing for substrate components. It can be said that silicone overmolding brings higher value to product design.
Liquid silicone overmolding can be subdivided into insert molding process according to different materials and placement positions of substrate components. From a practical standpoint, the hallmark base part material for insert molding is metal, as metals possess the necessary properties of high-temperature resistance as a base material and often have higher hardness gains.
For special material combinations, it may be necessary to fire, discharge and plasma treat the substrate. In addition, the adhesion between the substrate and the LSR needs to be tested in order to make optimal adjustments to the production details in time.
When is Overmolding Used?
If you want to take into account the functionality and aesthetics of medical devices, overmolding is a process worth considering. Using it, we can give products additional appearance and functionality, flexible components, etc.
Silicone overmolding supports the design of products such as additional ergonomics, color variation and brand identity. It allows the final assembly to have rigidity and flexibility suitable for healthcare, baby care, food-related applications, and other products that require a special combination of properties.
Medical Silicone Overmolding Solutions
As a leading manufacturer in the custom silicone rubber industry, Newtop Silicone has been providing high-quality LSR overmolding custom services to customers from all over the world for many years. We have accumulated rich production experience, and the product range covers medical parts fields.
Newtop Silicone provides all the services required for LSR overmolding, including pre-prototype custom design services, material performance testing consulting services, high-volume efficient production services, and product quality assurance services. Feel free to consult our experts for free.
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