The Process Steps of Liquid Silicone Rubber Injection Molding

Material Preparation
The process begins with the careful preparation of the LSR material. LSR typically comes in two-part systems, a base and a curing agent. These two components are precisely mixed in the correct ratio to initiate the curing process. The mixing can be done manually for small-scale production, but for high-volume manufacturing, automated mixing systems are used to ensure consistent quality. Once mixed, the LSR is ready to be injected into the mold.

Mold Design and Fabrication
The mold for LSR injection molding is designed with precision to accommodate the unique flow characteristics of the liquid rubber. Since LSR has a low viscosity when in its liquid state, the mold must be designed to prevent leakage and ensure proper filling of the cavity. The mold is often made of high-quality steel or aluminum and is fabricated using advanced machining techniques. For complex parts, such as those with intricate internal structures or undercuts, the mold may incorporate movable cores and slides to facilitate the molding process.

Injection and Curing
The mixed LSR is then injected into the mold cavity using an injection molding machine specifically designed for LSR. The injection pressure and speed are carefully controlled to ensure that the LSR evenly fills the mold cavity. Once the cavity is filled, the LSR is cured. Curing can be achieved through heat, typically in the range of 120-200°C, depending on the type of LSR and the part requirements. The curing time is also carefully regulated to ensure complete cross-linking of the rubber molecules, resulting in a solid, durable part.

Ejection and Finishing
After curing, the mold is opened, and the LSR part is ejected. In some cases, the part may require minimal finishing, such as trimming excess flash or removing any burrs. However, due to the precision of the injection molding process, many LSR parts can be used as-molded without significant post-processing.

Applications of Liquid Silicone Rubber Injection Molding

Toy

Soft-Touch Toys
In the toy industry, LSR injection molding is widely used to create soft-touch toys. These toys are not only more comfortable for children to hold but also safer as they are less likely to cause injury during play. For example, plush-like toys with soft, flexible bodies and limbs can be made using LSR. The material’s ability to mimic the feel of real-life textures, such as the softness of a teddy bear’s fur or the flexibility of a doll’s joints, makes it a popular choice. Additionally, LSR is biocompatible, ensuring that it is safe for children to handle and even put in their mouths.

Toys with Moving Parts
Toys with moving parts, such as action figures with flexible joints or pull-back toys with rubber wheels, also benefit from LSR injection molding. The flexibility of LSR allows for smooth movement of the joints, enhancing the playability of the toy. The rubber wheels made from LSR provide better traction and shock-absorption, making the toy more stable and enjoyable to play with.

Home Appliances

Gaskets and Seals
In home appliances, LSR is commonly used to produce gaskets and seals. These components are crucial for preventing leaks, whether it’s in a refrigerator door gasket to keep the cold air in or a washing machine door seal to prevent water from escaping. LSR’s excellent resistance to heat, moisture, and chemicals makes it an ideal material for these applications. The material can be molded into complex shapes to fit the specific requirements of each appliance, ensuring a tight and reliable seal.

Ergonomic Handles and Grips
LSR injection molding is also used to create ergonomic handles and grips for home appliances. For example, the handles on kitchen appliances like blenders or electric kettles can be made of LSR to provide a comfortable and non-slip grip. The soft-touch nature of LSR reduces fatigue during use and enhances the overall user experience.

Electronics

Flexible Printed Circuit Board (FPCB) Protectors
In the electronics industry, LSR is used to protect flexible printed circuit boards (FPCBs). FPCBs are widely used in electronic devices due to their flexibility and ability to save space. LSR can be injection-molded around the FPCBs to provide protection against moisture, dust, and mechanical stress. The material’s flexibility allows it to conform to the shape of the FPCB, ensuring complete coverage and protection.

Rubber-Keypad Membranes
LSR is also used to produce rubber-keypad membranes for electronic devices such as remote controls, keyboards, and mobile phones. The softness and tactile feedback of LSR make it ideal for creating keys that are comfortable to press and provide a distinct click-feel. The material’s durability ensures that the keypad membranes can withstand millions of keystrokes without losing their functionality.

Hardware Tools

Tool Handles with Soft-Touch Grips
In the hardware tools industry, LSR injection molding is used to create tool handles with soft-touch grips. Tools like screwdrivers, pliers, and hammers often have LSR-molded grips to improve the user’s grip and reduce hand fatigue during use. The soft-touch nature of LSR provides a more comfortable hold, especially when working for extended periods. The material’s resistance to wear and tear also ensures that the grip remains functional even after repeated use.

Rubber-Coated Components
Some hardware tool components, such as the tips of pliers or the jaws of clamps, may be rubber-coated using LSR. This rubber coating provides better grip on the objects being worked on and also helps to prevent damage to the surfaces of the objects. The LSR coating can be customized to have different levels of hardness and texture to suit the specific application.

Sports Goods

Protective Gear
In the sports goods industry, LSR is used to produce protective gear. For example, knee pads, elbow pads, and wrist guards often have LSR components. The flexibility and shock-absorbing properties of LSR make it an ideal material for protecting athletes from injuries. The material can be molded into shapes that conform to the body’s contours, providing a snug and comfortable fit.

Sports Equipment Grips
LSR is also used to create grips for sports equipment such as tennis rackets, golf clubs, and bicycle handlebars. The soft-touch and non-slip properties of LSR enhance the player’s grip on the equipment, improving control and performance. The material can be colored and textured to match the design and style of the sports equipment.

Our expertise in Liquid Silicone Rubber Injection Molding allows us to provide high-quality injection molding parts to industries such as Toy, Home Appliances, Electronics, Hardware Tools, and Sports Goods. The unique properties of LSR, combined with our advanced manufacturing processes, enable us to meet the diverse and challenging requirements of these industries, contributing to the development of innovative and high-performing products.