Full analysis of the liquid silicone veneer encapsulation process: how to achieve the perfect integration of plastic and silicone?

In the field of modern precision manufacturing, liquid silicone rubber (LSR) is gradually replacing traditional solid silicone rubber and becoming the preferred material for high-end products due to its outstanding elasticity, heat resistance and biocompatibility. The solid body rubber coating (i.e., the composite molding of plastic skeleton and liquid silicone) technology perfectly combines the structural support of hard materials with the touch comfort of soft materials, and is widely used in consumer electronics, medical devices, automotive interiors and other fields. However, achieving a "perfect blend" of plastic and silicone is not merely a simple physical stacking, but a systematic project involving materials science, mold design and process control. This article will delve into the core process of liquid silicone gel bulk coating and reveal the technical logic behind it. < I. Why choose liquid silicone gel solid coating? < Compared with traditional assembly methods, LSR solid body rubber coating has incomparable advantages: seamless bonding and no delamination. Through chemical bonding or mechanical interlocking, the silicone and plastic skeleton form an integrated structure, completely solving the pain points of easy aging and easy detachment in traditional adhesive processes. < High precision and complex structure realization: LSR's extremely low viscosity enables it to fill micron-sized gaps, making it suitable for manufacturing complex parts with fine textures, thin-walled structures, or internal inserts. < Automated production, efficiency improvement: In combination with cold runner molds and automated part retrieval systems, LSR overmolding can achieve 24/7 unmanned production, significantly reducing labor costs and enhancing product consistency. < Ii. Detailed Explanation of Core Process Steps 1. Pre-treatment of the base body: The Key starting point for bonding The cleanliness of the base body surface (typically engineering plastics such as PC, ABS, and PA66) directly determines the bonding strength. Any oil stains, mold release agent residues or oxide layers will lead to the failure of rubber coating. Therefore, Plasma Cleaning or ultrasonic cleaning must be adopted to activate the body, increase the surface energy and create conditions for subsequent chemical bonding. For non-self-adhesive materials, a special Primer should also be evenly applied. < 2. Mold Design: A delicate Balance between cold runner and positioning. LSR overmolded molds typically employ a cold runner system to maintain the low-temperature fluidity of the material within the runner and prevent premature vulcanization. At the same time, the mold needs to be equipped with a high-precision body positioning mechanism to prevent the body from shifting due to high injection pressure. Exhaust design is particularly crucial. Micron-level exhaust slots should be set at the parting surface and deep cavity. If necessary, vacuum-assisted injection molding should be introduced to eliminate the lack of glue or bubbles caused by trapped air. 3. Injection Molding: Dynamic Control of Temperature and Pressure. LSR vulcanization is extremely sensitive to temperature. The mold temperature is usually controlled between 120℃ and 180℃, and it is necessary to ensure that the temperature of the moving and fixed molds is uniform. The injection process adopts multi-stage curves: low-speed filling to protect the body and inserts, high-speed filling of the cavity, and low-pressure pressure holding to compensate for shrinkage. Precise setting of process parameters is the core to ensuring the dimensional stability of products. Iii. Common Challenges and Countermeasures: Optimize the surface of the prime body Sort out the process and select the primer that matches the substrate. Adjust the mold temperature to ensure that the silicone rubber is fully vulcanized and undergoes a chemical reaction with the substrate. < Challenge Two: Countermeasures for flash and overflow: Enhance the processing accuracy of the mold to ensure a tight fit of the parting surface. Optimize the matching of clamping force and injection pressure to avoid overflow caused by excessive pressure. Challenge Three: Internal Bubble Countermeasures: Enhance vacuum degassing treatment of raw materials; Optimize the exhaust structure of the mold and adopt vacuum injection molding technology. < The liquid silicone gel bulk coating process represents a high standard of precision manufacturing. Dongguan Fengyanda Life Technology Co., LTD., relying on its profound technological accumulation, has mature solutions in the LSR rubber coating field. From material selection to mold development and mass production control, it ensures product quality throughout the process. Selecting professional partners is the key to achieving product innovation and quality improvement.