What is the tolerance control for the mold of liquid silicone material and liquid silicone package metal parts? Will it not crush the mold?

Liquid silicone encapsulation technology, as a precision manufacturing process, is widely used in fields such as electronics, automotive, and medical, requiring extremely high dimensional accuracy and process control. This article will delve into the characteristics of liquid silicone, mold design, production process, and tolerance control principles to explore in depth the range within which mold tolerances should be controlled in order to effectively avoid mold damage and ensure product quality.
Characteristics and tolerance control of liquid silicone gel

Liquid Silicone Rubber (LSR) is widely popular due to its excellent high and low temperature resistance, aging resistance, electrical insulation, and good biocompatibility. However, in the process of coating metal parts with liquid silicone, its viscosity, flowability, curing speed and other characteristics pose serious challenges to tolerance control.

Viscosity and flowability: The viscosity of liquid silicone is a key factor affecting its flowability. Excessive viscosity can reduce the fluidity of silicone in the mold, which may lead to insufficient filling of corners and affect the coating effect; If the viscosity is too low, it may cause silicone to overflow from the mold and even damage the mold structure. Therefore, when selecting liquid silicone, it is necessary to adjust the viscosity of the silicone according to the shape, size, and tolerance requirements of the metal parts to ensure that it can smoothly fill the mold without causing damage to the mold.

Curing speed: The curing speed of liquid silicone is equally important. The curing speed is too fast, and the silicone may generate internal stress due to shrinkage or deformation during the filling process, which may damage the mold; If the curing speed is too slow, it may affect the coating quality due to external interference (such as temperature fluctuations and humidity changes) during the curing process of silicone. Therefore, controlling the appropriate curing speed is crucial for protecting the mold and ensuring product quality.
Mold Design and Tolerance Control

Mold is a key equipment for liquid silicone coated metal parts, and its design accuracy directly determines the dimensional tolerance of the product and the service life of the mold.
Mold dimensional accuracy: The dimensional accuracy of the mold should be higher than the dimensional tolerance requirements of the product to ensure the stability of the product dimensions. When coating metal parts with liquid silicone, the dimensional accuracy of the mold needs to be precise to the micrometer level to reduce product dimensional deviations caused by insufficient mold accuracy. At the same time, the design of the mold should fully consider the fluidity of liquid silicone, avoiding structures such as dead corners and sharp angles that are not conducive to the flow of silicone.

Mold tolerance setting: The setting of mold tolerance needs to comprehensively consider the dimensional tolerance of metal parts, the flowability of liquid silicone, the curing speed, and various factors in the production process. Generally speaking, the tolerance of the mold should be slightly greater than the dimensional tolerance of the metal parts to reserve sufficient space for silicone filling and avoid mold damage caused by silicone compression. Specifically, for the secondary molding of liquid silicone on metal parts, it is required that the tolerance of the metal parts be within 0.02mm, and only the tolerance can be lowered. The mold should reserve appropriate tearing space (such as about 0.06mm) at the sealing position to ensure perfect joint surfaces and no damage to the mold.
Production process and tolerance control

The optimization of production process is one of the key factors to ensure tolerance control of liquid silicone coated metal parts.
Injection temperature, pressure, and speed: Injection temperature, pressure, and speed are important parameters that affect the flow and solidification of liquid silicone in the mold. High or low temperature, high or low pressure, and fast or slow speed can all lead to product quality problems or mold damage. Therefore, in the production process, it is necessary to accurately control these parameters based on the characteristics of liquid silicone and the shape and size of metal parts, to ensure that silicone can be uniformly and stably filled into the mold.
Environmental control: Factors such as temperature, humidity, and cleanliness in the production environment can also affect the performance of liquid silicone gel and the accuracy of molds. Therefore, it is necessary to strictly control the production environment to ensure that silicone is coated under stable conditions and reduce the impact of external factors on product quality and mold tolerances.

summary

When liquid silicone is used to coat metal parts, the control of mold tolerances is a complex and delicate process that involves multiple aspects such as the characteristics of liquid silicone, mold design, production process, and environmental control. In order to ensure product quality and mold safety, it is necessary to comprehensively consider various factors based on specific situations and develop reasonable tolerance control strategies. Generally speaking, the tolerance of metal parts should be controlled within 0.02mm. The mold should reserve appropriate tearing space at the sealing position and strictly control parameters such as injection temperature, pressure, speed, and production environment.