To know what is silicone overmolding, we should know what is overmolding at first. Overmolding means to do one more molding on the molded part, it can also be called insert molding or second injection molding. Silicone can be overmolded with other materials to do secondary molding, therefore we name it silicone overmolding. Since silicone can be divided into two forms, solid silicone and liquid silicone, for silicone overmolding, there are two kinds of technics, that is, compression overmolding and LSR injection overmolding.
1. Enhanced Performance: Overmolding combines the best properties of silicone (flexibility, temperature resistance, chemical resistance, and non-stick properties) with the strengths of the base material (e.g., rigidity, strength, or electrical conductivity).
2. Improved Grip and Comfort: The soft, flexible nature of silicone provides a comfortable, ergonomic grip or tactile feel, making it ideal for products like handles, buttons, and wearable devices.
3. Aesthetic Appeal: Silicone overmolding can provide a clean, smooth finish, and allows for the use of different colors, textures, or even transparent materials for visual appeal.
4. Sealing and Waterproofing: Silicone overmolding creates a waterproof seal between the substrate and the silicone layer, which is essential in consumer electronics, medical devices, and automotive components.
5. Durability and Longevity: Silicone rubber is resistant to UV rays, extreme temperatures, and environmental degradation, which enhances the durability of overmolded products.
6. Precision and Detail (especially with LSR Injection): LSR overmolding offers high precision and tight tolerances, which is essential for parts that need fine details, high part quality, or complex geometries.
1. High Tooling Costs: The tooling required for both compression and LSR overmolding can be expensive, particularly for custom or highly intricate designs, although the cost is amortized over large runs.
2. Material Compatibility Issues: The adhesion between silicone and certain materials (like some plastics) can be challenging, requiring special surface treatments or primers to ensure a strong bond between the silicone and the substrate.
3. Complexity of the Process: The need to handle multiple materials and molding steps can make overmolding more complex than standard molding processes. It may also require precise control of temperature and pressure.
4. Limited to Certain Materials: Not all substrates are suitable for overmolding with silicone. Materials with low surface energy or those that are incompatible with silicone may not bond well, limiting the range of substrates that can be used.
5. Cycle Time (especially in LSR Injection): LSR injection overmolding can have longer cycle times compared to traditional injection molding, particularly in multi-step or high-precision applications. The curing process for silicone can also extend the production time.
6. Surface Imperfections: If the molding process isn't precisely controlled, there can be issues such as air pockets, uneven silicone distribution, or defects in the final part.
Due to the temperature limit of silicone overmolding, the overmolding materials should be able to withstand a certain temperature, usually, the materials can be overmolded with silicone are PC, PA, PEI, PPSU, fabric, SUS, steel, iron and so on. Also, if you want to achieved different hardnesses or colors, silicone can also be overmolded with silicone material.
| Plastic | Fabric | Metal | Silicone |
1. Silicone itself plays a sealing role, so to make products to be waterproof or leak-proof. While in assembling or inserting, since silicone is soft, so it needs to be processed in a certain interference, which makes it have to be supported with a hard part.
2. When we do assembly for a product, the more parts to be assembled, the more difficult to improve the capacity and quality stability, esp., for some tiny parts. With silicone overmolding process, it optimizes the assembly processes, and makes it more easier to assemble small parts.
3. Usually, a product with complicated assembly processes, the assembly costs will be much higher. If some parts can be done by silicone overmolding and become a united part, the assembly costs will be lower, also the assembly efficient will be more stable.
1. Medical Devices: Overmolding is widely used to create biocompatible parts like syringe handles, surgical instruments, and connectors. The silicone layer offers cushioning, grip, and chemical resistance.
2. Consumer Electronics: Silicone overmolding is used for products like smartphone cases, remote control buttons, wearables (like fitness trackers), and seals, enhancing comfort, waterproofing, and impact resistance.
3. Automotive Industry: Components such as gaskets, seals, handles, and knobs benefit from overmolding, providing durability, vibration damping, and weather resistance.
4. Household Goods: Kitchen tools, grips for appliances, and seals for containers often use silicone overmolding to combine a rigid base with a soft, heat-resistant grip.
5. Sports and Recreation: Overmolded grips for sports equipment, handles, and personal protection gear (e.g., wristbands, gloves) offer both comfort and durability.
6. Electrical Components: Overmolding provides insulation and protection for electrical connectors, switches, and wiring, ensuring longevity and electrical safety.
Silicone overmolding are widely used in various industries, the most common one is consumer electronics, such as connectors, mobile phones, smart watches, etc., as long as there are holes needed to be sealed, which is why we have produced many IP67 or IP68 waterproof silicone overmolded components for mobile phones and outdoore electornics. Nowadays, many products are in pursuit of premium quality, for example, beauty products, by silicone overmolding, the overall effect of the product will be more aesthetically, and easier to clean.
As you may know the physical properties of silicone are very stable, and if it needs to be overmolded with other materials, an adhesive agent is required. What kind of agents shall be choosed, positioning, temperature and injection pressure are also very important while in silicone overmolding, otherwise it will cause various defective products, such as, excessive burrs, lack of silicone material, air bubble, misalignment, etc. Our engineers are familiar with technical know-how of silicone overmolding, and are very familiar with the characteristics of silicone materials, and can precisely control the injection dose, molding pressure and temperature. Here we'd like to introduce some of the silicone overmolding products that we've manufactured.
The SIM card tray holder is made of aluminum, liquid silicone and plastic materials, processed by liquid silicone rubber overmolding injection, the waterproof level reaches to IP68.
Safety comes first, outdoor monitoring is increasingly popular today, waterproof is a must function for all outdoor monitoring devices. This camera keypad is made of liquid silicone and plastic materials, and it's IP67 waterproof.
Home beauty products are becoming more and more high-end, and many ultrasonic beauty instruments require a sophisticated appearance. This overmolding plastic holder is made of medical grade liquid silicone and plastic materials, not only it's IP68 waterproof, but also it's requested to be flash free after LSR overmolding injection. If interested, you can check the production process of it.
Made of silicone and stainless steel materials, each stainless steel pin is CNC machined, resulting in large variations in dimensional tolerances that are difficult to position when overmolding, but our professional engineering team solves this problem for our customers and received many compliments.
If you're looking for professional silicone overmolding factory, please feel free to contact us. With over 10,000 square meters silicone molding workshops, including class 100,000 clean production workshop, our factory has been certified by ISO9001, ISO14001, ISO13485 and IATF16949 for making custom silicone products.
