Blue Print Guide Of Silicone Overmolding

May. 26, 2023

Silicone overmolding is also called silicone rubber overmolding, liquid silicone overmolding, silicone over-molding. Hopewell Silicon has more than 10 years of experience in the production of silicone overmolding products, I will introduce the relevant knowledge of silicone overmolding in detail next.


What is silicone overmolding?

silicone overmolding refers to a process technology in which liquid silicone rubber and other materials(such as plastics, hardware, etc.)  are thermally processed under a certain temperature and pressure through a precision mold liquid injection machine. Usually, the silicone overmolding temperature is 110-130 degrees, the pressure will be determined according to the size of the mold, generally between 60kg/cm²-100kg/cm².

Blue Print Guide Of Silicone Overmolding


Advantages of silicone overmolding?

Silicone overmolding can realize the sealing of complex structures and reduce the number of parts assembled, thereby reducing assembly costs.

1. Reduce the number of parts assembled

Multi-component technology is one of the latest development trends in the field of sealing, the fusion of multiple components provides the possibility to achieve a unique sealing shape. Manufacturers of electronic systems, electric drives and medical devices are always looking for ways to simplify assembly and reduce the number of parts required while maintaining functionality and performance.


2. Realization of complex structure sealing

By firmly combining multiple materials, components can take advantage of the properties of different materials and combine various functions in a single integrated part, which is not only affordable but also extremely reliable. Silicone overmolding is suitable for various industry requirements, so it can be widely used in various fields, reducing the number of parts required to simplify the installation process and shortening the installation time are two of the most common application requirements.


What products are suitable for the silicone overmolding process?

Due to the advantages of liquid silicone rubber (LSR), such as good flexibility, wide temperature application range, high appearance value, excellent chemical inertness and biocompatibility, so if the products have waterproof requirements, high sealing requirements, or high assembly sales, they will be suitable for silicone overmolding process. For example:

1. Electronic products, hardware products, daily necessities for beauty, mother and baby also often see the application of silicone overmolding products.

2. Silicone bonding of mobile phone cases, mobile phone card holders, push rods, silicone wristbands, PC buttons, silicone integrated feeding bottles or pacifiers, medical mouthpieces, silicone pads, related to the medical beauty industry, auto parts Aviation industry, electronic product accessories industry and so on.



Which process is the most important in the silicone overmolding process?

In the silicone overmolding process, there are two most important processes:

1. Spray binder

If the binder is not sprayed in place according to the designated area, it will lead to degumming of the product, and degumming will occur if the timeliness is not well controlled.


2. LSR liquid injection molding

The design of the mold directly affects the molding quality and production efficiency of the product. The key to precision injection molding lies in mold manufacturing, temperature control, feeding pressure control, etc. If the design of the mold is unreasonable and the manufacturing process is not standardized, it will lead to a decrease in production efficiency and product quality.

Blue Print Guide Of Silicone Overmolding


What are the common defects in the silicone overmolding process? What is the cause?

There are three main disadvantages:

1. Degumming: Degumming will occur if the bonding agent is not sprayed in place.

2. Lack of material: The exhaust of the mold design is not done well, resulting in trapped air.

3. Crushing: If the materials are not placed neatly before forming, the product will be crushed.

What are the advantages of silicone overmolding production process in Hopewell?

The precision of the molds designed and manufactured by Hopewell can reach 0.005MM, the precise mold design can make the perfect combination of silica gel and materials. For the silicone overmolding products, Hopewell has a special management system:


For material pre-processing technology:

1. It will be baked in the oven to remove moisture

2. After ultrasonic and plasma treatment to clean the oil and dust attached to the surface of the material;


For spraying bonding glue process:

1. Spraying fixture according to the structure of the material (it can meet the requirements of customers, 100% can be sprayed in place according to the needs, and there is no overflow glue. Increase the production efficiency)

2. Equipped with Musashi brand precision nozzle

3. Automatic dispensing machines will be available for products with high demand

Blue Print Guide Of Silicone Overmolding


The complexity of products and applications requires us to have professional engineering technology and advanced equipment, our engineer team is always ready to serve you and work with you to create the best product performance and the most cost-effective silicone overmolding products. If you are interested in silicone overmolding products, please contact us.

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