What is the thickness of liquid silicone gel for metal parts packaging?

The thickness of liquid silicone for metal parts packaging is a problem involving multiple factors, and its final determination needs to consider the size, shape, purpose of the metal parts, as well as the material characteristics and molding process of the liquid silicone.

Basic characteristics of liquid silicone gel

Liquid Silicone Rubber (LSR) is a high-performance elastic material with excellent high and low temperature resistance, chemical corrosion resistance, good electrical insulation performance, and biocompatibility. During the molding process, liquid silicone can be tightly bonded to metal parts through injection molding, compression molding, or transfer molding processes to form a strong coating layer. Liquid silicone has good fluidity and can fill the surface of complex shaped metal parts to form a uniform coating layer.

Application scenarios of metal parts coated with silicone

The application of liquid silicone gel coating on metal parts is very extensive, including but not limited to the following aspects:
1. Electronic products: Waterproof and dustproof sealing components for devices such as mobile phones and tablets, which achieve good sealing effect by coating metal parts with liquid silicone.
2. Automotive parts: such as sensors, connectors, and other components in the engine compartment, are coated with liquid silicone to improve their temperature resistance, oil resistance, and vibration resistance.
3. Medical devices: Components such as surgical instrument handles and catheters are coated with liquid silicone to improve comfort and biocompatibility during use.
4. Household appliances: Seals and handles of appliances such as electric kettles and rice cookers are coated with liquid silicone to improve slip resistance and temperature resistance.

Key factors affecting thickness

The thickness of liquid silicone gel coating on metal parts is influenced by multiple factors, mainly including the following aspects:
1. Size and shape of metal parts: The larger the size of the metal parts, the thicker the required silicone coating layer to ensure sufficient strength and sealing. Meanwhile, the shape of metal components can also affect the distribution and thickness of the silicone layer.
2. Material properties of liquid silicone: The viscosity, flowability, curing speed, and other characteristics of liquid silicone can affect its distribution and thickness on the surface of metal parts. High viscosity liquid silicone is not easy to flow during the molding process, which may result in uneven thickness.
3. Molding process: The selection of molding process and parameter settings can also affect the thickness of the silicone layer. For example, parameters such as injection pressure, injection speed, and mold temperature during injection molding can affect the distribution and thickness of the silicone layer.
4. Requirements for application scenarios: Different application scenarios have different requirements for the thickness of the silicone layer. For example, waterproof and dustproof seals require a thick silicone layer to ensure sealing effectiveness; The grip of surgical instruments requires a thinner silicone layer to improve comfort during use.

Suggestions for setting specific thickness

Based on the size, shape, and purpose of the metal parts, as well as the material characteristics and molding process of the liquid silicone, we can provide the following suggestions for setting the thickness of the liquid silicone coating on the metal parts:

1. General requirements:

For most metal parts, it is recommended that the minimum thickness of the silicone coating layer should not be less than 0.5mm to ensure sufficient strength and sealing.
When the size of the metal part is small (such as the maximum size within 30mm) and reliable support or positioning is required, the thickness of the silicone coating can be controlled at around 0.3mm on one side.

2. Special application scenarios:

For metal parts that require significant pressure or tension, such as sensors and connectors in car engine compartments, the thickness of silicone coating can be appropriately increased to improve their durability and sealing.
For medical device components that require good biocompatibility, such as surgical instrument handles and catheters, the thickness of silicone coating can be controlled within a relatively thin range to improve user comfort and reduce patient foreign body sensation.

3. Limitations of molding process:

During the secondary molding process of liquid silicone, parameters such as mold temperature and injection pressure can affect the distribution and thickness of the silicone layer. Therefore, when setting the thickness of the silicone layer, it is necessary to consider the limitations of these process parameters.
For the secondary molding of liquid silicone for metal parts, it is required that the tolerance of the metal parts be within 0.02mm, and only the tolerance can be lowered. This way, the mold is not easily crushed when it reaches the size, and a tearing edge should be done around 0.06mm on the sealing position side. This can make the joint surface more perfect. If the size tolerance is too large, it will either make it difficult to tear the edges or damage the mold.

4. Economic and feasibility considerations:

When setting the thickness of the silicone layer, economy and feasibility also need to be considered. Excessive thickness of silicone layer will increase material and processing costs; However, a thin silicone layer may not meet the requirements for strength and sealing. Therefore, it is necessary to reasonably control the thickness of the silicone layer while ensuring performance.
Practical application cases

The following are some practical application cases of metal parts coated with liquid silicone, which demonstrate the setting of silicone layer thickness in different application scenarios:
Waterproof and dustproof seals for mobile phones: In mobile phones, waterproof and dustproof seals are usually made of liquid silicone coated metal parts. These seals are usually located on the speaker, microphone, charging port, and other parts of the phone. In order to ensure good waterproof and dustproof effects, the thickness of the silicone layer of these seals is usually not less than 1mm.