Addition-cure liquid silicone rubber (LSR) has gained widespread application in two seemingly disparate fields—industrial manufacturing and healthcare—thanks to its precise replication capabilities and tunable physical properties. From replicating micron-level textures in art crafts to fabricating orthopedic aids that conform to human body contours, this material demonstrates remarkable adaptability.

Precision Assurance in Industrial Molds

In mold silicone applications, linear shrinkage is the core metric for evaluating replication accuracy. High-quality addition-cure mold silicone can achieve a linear shrinkage rate of less than 0.1%, meaning that for a 500 mm long master pattern, the dimensional deviation after replication does not exceed 0.5 mm—a precision level that meets the tolerance requirements of most industrial components. For prototypes with complex surface textures (such as leather grain, wood grain, or stone carving details), the flowability of silicone ensures it can fully penetrate microscopic depressions and faithfully reproduce detailed surface features.

Mold silicone offers a wide hardness range (Shore A 10–60). Low-hardness products (10–20 Shore A) are suitable for crafting detailed molds with complex undercuts that are difficult to demold; medium hardness (30–40 Shore A) is the mainstream choice for industrial part replication, balancing strength and elasticity; high-hardness products (50–60 Shore A) are used for production molds requiring repeated long-term use. Food-grade mold silicone must also comply with FDA 21 CFR 177.2600 or GB 4806.11 standards to ensure safety in food-contact applications.

Biocompatibility in Medical Aids

The application of body-contact silicone in the medical rehabilitation field imposes even higher requirements on materials. The addition-cure system employs platinum as a catalyst, producing no by-products during curing and thus avoiding the potential skin irritation caused by alcohol by-products released by condensation-cure silicones. Materials that meet ISO 10993 biocompatibility testing requirements can be used in products that have prolonged skin contact, such as prosthetic sockets, orthopedic insoles, and facial prostheses.

In prosthetic socket fabrication, the hardness of the silicone liner is typically selected in the ultra-soft range of Shore A 0–20, mimicking the cushioning properties of human adipose tissue, distributing pressure between the residual limb and the socket, and reducing skin abrasion and pain. Test data indicate that an appropriate silicone liner can reduce peak pressure at the residual limb-socket interface by 30%–50%, enhancing wearing comfort. Platinum-cured silicones used in special effects makeup similarly pursue skin-like tactile qualities, and can be pigmented to simulate various skin tones and textures.

Critical Process Control Points

Addition-cure silicone is sensitive to catalyst poisoning; compounds containing sulfur, phosphorus, or nitrogen (such as certain rubber gloves, PVC plasticizers, and polyurethane release agents) may inhibit platinum catalytic activity, leading to incomplete curing. The operating environment should be kept clean, and tool material compatibility should be confirmed before use. Vacuum degassing is an essential step to ensure mold surface smoothness—residual bubbles will create surface depressions in the mold, compromising replication quality. For large molds, layered pouring with controlled layer thickness (recommended not exceeding 20 mm per layer) facilitates heat dissipation and prevents poor deep-section curing.

Industry Development Trends

In the cultural and creative industry, the combination of 3D-printed prototypes and silicone mold replication has significantly shortened the cycle from design to finished product, making silicone molds an economical choice for small-batch custom production. In the medical field, the integration of digital impression-taking technology with customized silicone aids is advancing the fitting accuracy of prosthetic sockets from millimeter-level to sub-millimeter-level, enhancing users' daily mobility and quality of life.

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