What are the reasons for the formation of parting lines in liquid silicone encapsulated products?

Liquid silicone encapsulated products have excellent physical and chemical properties in modern industrial production, such as high temperature resistance, low temperature resistance, weather resistance, waterproofing, etc., making them widely used in multiple fields such as electronics, medical, and automobiles. However, in the production process of liquid silicone encapsulated products, the issue of parting line has always been an important factor affecting product quality and appearance.

Mold design: If the design of the mold is unreasonable or the manufacturing accuracy is insufficient, it can lead to loose clamping.

Mold closing pressure: If the mold closing pressure is uneven or too large or too small, it may affect the surface quality of the product.

Silicone rubber material: The fluidity and curing speed of the material itself can also affect the generation of parting lines.

Injection process parameters: If the injection speed is too fast, it may cause air entrainment.
Excessive filling time may lead to excessive flow and the formation of joints.
Improper temperature control may also cause inconsistent material flow.
The use of release agents: Improper or excessive use of release agents can also lead to the formation of parting lines.

Insufficient or excessive vulcanization time: The vulcanization time has a significant impact on the performance of silicone rubber, and inappropriate time settings may lead to surface defects of the product.

Cooling system design issue: If the cooling system inside the mold is poorly designed, resulting in uneven cooling in local areas, irregular shrinkage and seam problems may occur.

Operating skills and experience level: The technical level of operators has a significant impact on product quality. Unskilled operators may not be able to accurately control the injection molding process or fail to adjust in a timely manner to respond to changes in machine status

Environmental factors: Temperature, humidity, and other factors in the production environment can indirectly affect the molding effect

Equipment maintenance: If the maintenance of equipment such as hydraulic presses is not in place, such as reduced sealing of the hydraulic system or inaccurate calibration of the control system, it may also affect the final quality of the product

We can make improvements in the following areas to address the issue of parting lines in liquid silicone encapsulated products:
1、 Optimize raw material selection. Choose silicone raw materials with high purity, uniform viscosity, and moderate vulcanization speed to ensure stable flowability of silicone during the encapsulation process.
2、 Strengthen equipment maintenance and cleaning. Regularly clean and maintain the mold to ensure its accuracy and cleanliness. At the same time, strengthen the control of equipment temperature and pressure to ensure the stable flow of silicone in the mold.
3、 Adjust process parameters. Reasonably control the encapsulation speed and time to ensure the stable fluidity of silicone gel in the mold. At the same time, optimize the glue ratio and mixing uniformity to ensure the stability of the viscosity and fluidity of the silicone gel.
4、 Control the production environment. Reasonably control the temperature and humidity of the production environment to ensure the stable flowability of silicone in the mold. At the same time, strengthen the cleaning of the production environment and reduce the impact of dust and impurities on the parting line.
In summary, the reasons for the formation of parting lines in liquid silicone encapsulated products are multifaceted, requiring comprehensive analysis and improvement from multiple aspects such as raw materials, equipment, process, and environment. Only in this way can the generation of parting lines be effectively reduced, and the quality and appearance of liquid silicone encapsulated products be improved.