Fumed silica gel is easier to demold than precipitated silica gel. This conclusion can be analyzed from the following aspects:
Correlation between physical properties and demolding
Transparency and demolding observation
The transparency of fumed silica gel is significantly higher than that of precipitated silica gel, and its transparency ranges from translucent to fully transparent. This feature enables operators to clearly observe the state of the casting material inside the mold during mold making and demolding, such as whether bubbles or uneven filling are generated. Timely detection of problems can reduce rework and indirectly improve demolding efficiency.
Tensile properties and mold separation
The tensile strength of fumed silica gel can reach 7.8-10.0MPa, the tear strength is up to 49kN/m, and the elongation is in the range of 500-1000%. These mechanical performance indicators far exceed those of precipitated silica gel (tensile strength 4-7MPa, elongation 150-300%), which means that fumed silica gel can withstand greater deformation without breaking during demolding, thereby reducing the risk of adhesion between the mold and the product.
Compression set rate
The compression set rate of fumed silica gel is less than 10%, indicating that it can quickly recover to its original state after repeated compression. This property is particularly important in the demolding process, ensuring that the dimensional accuracy is quickly restored after the mold and the product are separated, avoiding demolding difficulties caused by deformation.
Correlation between chemical properties and demolding
Temperature resistance and demolding process compatibility
The temperature resistance range of fumed silicone is -60℃ to 250℃, which is much wider than precipitated silicone. In the high-temperature demolding process, fumed silicone can maintain stable performance and avoid mold deformation or product adhesion caused by temperature changes. For example, in the manufacture of medical catheters, the temperature resistance of fumed silicone can support direct demolding after high-temperature vulcanization without additional cooling steps.
Chemical corrosion resistance and release agent compatibility
Fumed silicone has ozone aging resistance and is not easy to adsorb chemicals on the surface. This property makes it more compatible with the release agent, which can evenly cover the mold surface, reduce the friction between the product and the mold, and thus improve the demolding efficiency.
Demolding performance in actual applications
High-precision mold manufacturing
Fumed silicone is often used in the manufacture of high-precision molds such as imitation gemstones and resin diamonds. Its high transparency and low compression set ensure mold dimensional accuracy, while its excellent tensile properties support demolding of complex structures. For example, in jewelry mold manufacturing, fumed silicone can achieve accurate replication of tiny details and maintain product integrity during demolding.
Applications in the medical and food fields
Fumed silicone has passed medical grade certification (such as the NE-9100 series) and is suitable for the manufacture of medical products such as catheters. Its non-toxic and anti-yellowing properties ensure product safety, while its high elasticity supports bending and stretching during demolding to prevent product breakage. In the manufacture of food-grade silicone products (such as pacifiers), the transparency and tear strength of fumed silicone can also improve demolding efficiency.
Industrial component manufacturing
Fumed silicone (such as 600160 molding glue) has a tear strength of 36kN/m and is suitable for the manufacture of high-tear industrial components. For example, in the manufacture of pressure cooker rings, the tear strength of fumed silicone ensures that the sealing ring can be easily demolded after repeated use, while precipitated silicone may be difficult to demold due to insufficient tear strength.