For years, 3D printing has been dominated by thermoplastics like PLA and ABS, along with photopolymer resins. However, the recent rise of flexible electronics, personalized medicine, and soft robotics has fueled a surge in demand for printable elastomers. As a high-performance elastomer, silicone rubber is gaining prominence in 3D printing material research due to its excellent biocompatibility, temperature resistance, and chemical stability. From indirect molding to direct extrusion, silicone rubber 3D printing is sparking a "flexible manufacturing revolution."

1. Early Approach: Silicone Replication (Indirect Printing)

Before direct silicone printing became viable, 3D printing was commonly used to create master molds for reproducing silicone components:

High-resolution prototypes were printed using photopolymer resins.

Liquid silicone rubber (LSR) was then poured over these molds after applying a release agent.

After curing, the silicone replicas—soft and often transparent—were peeled off.

This method has been widely applied in custom prosthetic liners, biomimetic organ models, and microfluidic chip prototypes. Its advantages include low cost and reliable material properties, but it suffers from cumbersome processes and difficulties in producing complex internal structures such as enclosed cavities.

2. Breakthrough: Direct Silicone Rubber 3D Printing

In recent years, several companies and research institutions have successfully implemented direct additive manufacturing with silicone rubber. The primary techniques include:

Extrusion-based Printing:

High-viscosity two-component addition-cure silicone rubbers (A/B gels) are used.

These materials are mixed in real-time via static mixers before being extruded through precision nozzles.

Layers are rapidly cured using platinum catalysts, sometimes with UV or thermal assistance.

Representative platforms include Germany's Wacker Chemie’s ACEO® and Spectroplast in the USA.

This method can produce parts ranging from Shore A 10 to 70, with accuracies up to ±0.1 mm, suitable for custom seals and flexible sensor housings.

Inkjet/Drop-on-Demand Printing:

Low-viscosity silicone inks are selectively jetted onto substrates.

After layer-by-layer deposition, the entire structure is thermally cured.

This technique is ideal for creating ultra-thin films (<100 μm) or gradient hardness structures.

Vat Photopolymerization (Light-Curing):

Developable vinyl/mercapto-functional silicones that can be crosslinked under UV light (385–405 nm).

This method offers high resolution (<50 μm), although mechanical properties may not match those of traditionally vulcanized silicones.

3. Core Challenges and Solutions

Challenge     Solution

Rapid curing vs. print window   Optimize catalyst concentration to extend pot life (>30 minutes)

Weak interlayer bonding   Incorporate post-processing methods like heat/UV treatment to promote interface crosslinking

Difficult removal of support structures   Develop water-soluble supports or self-supporting algorithms for overhangs

High material costs    Promote domestic production and scaling of specialized silicone inks

4. Typical Applications

Personalized Medicine: Custom-printed silicone tracheal stents and auricular prostheses based on patient-specific CT data.

Soft Robotics: Integrated printing of actuators with air chambers, eliminating the need for assembly.

Microfluidic Chips: Direct construction of 3D intersecting channels and valve structures.

Aerospace Seals: On-demand printing of customized O-rings, reducing inventory needs.

5. Future Prospects

Multi-material Co-printing: Combining silicone with conductive fillers or hydrogels to achieve functional integration.

4D Printing: Structures that autonomously deform under thermal or moisture stimuli.

Closed-loop Recycling: Development of depolymerizable silicone inks to enable recycling and reuse.

Conclusion

The significance of silicone rubber 3D printing lies not just in the ability to "print" but also in transforming flexible devices from "standard mass production" to "personalized intelligent manufacturing." It blurs the line between design and fabrication, allowing soft, transparent, and biocompatible silicone structures to grow precisely according to digital blueprints. Whether at our fingertips or in the depths of exploration, this technology paves a precise path toward a future defined by flexibility and customization.



High resilience fluorosilicone rubber MY FHTV 3270 series-Mingyi Silicone