Silicone 3D printing is an emerging technology that holds great promise for creating soft, flexible objects with complex geometries. As more companies develop silicone 3D printers and materials, this technology is poised to transform industries like consumer products, medical devices, wearables, and more.
In this comprehensive guide, we’ll explore what makes silicone a unique 3D printing material, the different methods used for silicone 3D printing, key benefits and applications, and the future outlook for this exciting technology.
What is Silicone and Why is it Ideal for 3D Printing?
Silicone is a synthetic polymer made up of silicone atoms, oxygen, carbon, and hydrogen. It has an inorganic silicone-oxygen backbone chain with organic methyl groups attached.
Silicone’s chemical structure gives it a number of useful properties that make it well-suited for 3D printing, including:
- Flexibility – Silicone has a low modulus of elasticity, meaning it can bend and flex easily without breaking. This makes it possible to 3D print complex geometries.
- Durability – Silicone is resistant to extreme temperatures, oxidation, and water. Printed silicone parts retain their shape and mechanical properties over time.
- Biocompatibility – Medical grade silicone is non-toxic and hypoallergenic. This allows it to be used for biomedical devices and wearables that interface with the human body.
- Heat resistance – Silicone can withstand very high temperatures of over 200°C. Printed silicone molds can be used for casting metals and other high-melting point materials.
- Electrical insulation – With its high dielectric strength, silicone is an excellent insulator and can be 3D printed into custom cable covers and electronics housings.
The elasticity, durability, and biocompatibility of silicone open up many applications that are difficult or impossible with rigid thermoplastics like ABS and PLA. As 3D printing processes are developed to work with silicone, its unique properties can be leveraged to fabricate end-use products.
Key Methods of Silicone 3D Printing
There are two main approaches that allow silicone to be 3D printed:
- Material Extrusion
- Vat Photopolymerization
Material Extrusion Silicone Printing
Material extrusion works similarly to traditional FDM 3D printing. The printer has a print head with a nozzle that heats and extrudes silicone in a liquid state which then solidifies on the print bed.
The biggest challenge with this method is finding a silicone material that can be extruded at reasonable temperatures, while still retaining its flexibility and mechanical properties after printing. Fabricating the print nozzle to withstand repeated heating and extruding of high viscosity silicone is also difficult.
However, material extrusion offers benefits like lower material costs, no support structures needed, and multi-color/multi-material printing capabilities. Several companies like Formlabs and Wacker Chemical have developed customized silicone 3D printers based on material extrusion.
Vat Photopolymerization of Silicone
Vat photopolymerization (VPP) is commonly used for printing UV-curable resins in stereolithography (SLA) and digital light processing (DLP) 3D printers. For silicone 3D printing, modified silicones that cure under UV light are used as photoresins.
The silicone resin is contained in a vat, while an ultraviolet laser (SLA) or projected UV image (DLP) traces each layer pattern, causing the resin to solidify. After printing, the object must be rinsed and post-cured to fully harden it.
VPP enables excellent resolution and surface finish, along with the ability to print specialized silicone materials tailored for different applications. However, printed objects can suffer from weak support structures and require extra processing steps.
Hybrid Mixing Nozzle Approach
A third interesting approach combines material extrusion and VPP by using a mixing nozzle print head. Two liquid component silicones are mixed together in the nozzle right before deposition and cure nearly instantly when exposed to air.
This method allows for precise control over the silicone cure time and rheological properties. Desktop Metal’s Live SLA 3D printer platform utilizes this hybrid mixing nozzle technology for silicone printing.
Key Benefits and Applications of Silicone 3D Printing
Let’s look at some of the unique benefits that silicone 3D printing provides and how they enable new applications across industries:
- Custom soft robots – Silicone’s flexibility and elasticity make it a perfect material for pneumatic actuators and inflatable structures used in soft robotics. Custom silicone robots can be 3D printed that replicate natural motion.
- Comfortable wearables – Silicone parts like watch bands, rings, bracelets, and other wearables with conformal fitting can be 3D printed. Silicone is hypoallergenic and resistant to moisture and sweat.
- Biocompatible medical devices – With FDA-approved silicone grades, 3D printing enables customized silicone prosthetics, orthotics, cushioning, grips, and other medical tools.
- Durable industrial components – Printed silicone parts for machinery, jigs, fixtures, handles, and seals withstand chemical and high temperature environments. Silicone molds for metal casting can also be 3D printed.
- Dampening and anti-vibration – Silicone’s shock absorbing properties allow 3D printing of pads, bumpers, and mounts to reduce vibration and noise in products.
- Electrical insulation – Custom silicone cases, wire covers, and other insulating components can be 3D printed as needed, since silicone is an excellent electrical insulator.
These examples illustrate silicone 3D printing’s versatility for fabricating both end products and manufacturing tooling. As the technology progresses, many more applications will be discovered across industries like consumer goods, aerospace, automotive, and electronics.
Advantages of Silicone 3D Printing vs Traditional Methods
Compared to conventional fabrication methods for silicone parts like injection molding or CNC machining, 3D printing with silicone offers several advantages:
- Design freedom – Intricate geometries, internal structures, and complex curves that cannot be injection molded are possible by 3D printing silicone. Minimal part assembly is needed.
- Customization – Silicone 3D printing enables cost-effective customization and personalization for end-use parts and medical devices tailored to an individual.
- Rapid prototyping – Designs can be quickly iterated and parts 3D printed without the lead time and cost of tooling like injection molds. Helpful for design validation.
- Production agility – No mold tooling allows fast setup and economical short batch production runs. Easy to modify designs for rapidly changing needs.
- Reduced waste – Additive printing deposits only required silicone for each part, leading to less wasted material than subtractive machining methods.
While 3D printing has higher part costs for large volume production, it competes favorably with silicone molding and machining for low to moderate volumes needed for custom end-use parts. The ability to rapidly prototype and manufacture silicone components gives designers more freedom.
Silicone 3D Printing Material Options
Silicone chemistry allows modification of properties like hardness, tear strength, elongation, temperature resistance, and biocompatibility. By adjusting the polymer backbone and side chains, silicone can be optimized for different 3D printing processes and applications.
Popular materials include:
- Heat-cured silicones – Offer high purity, resistance, and durability. Used for industrial components and moldmaking.
- Addition-cured silicones – Cure via platinum catalyst addition, giving great print resolution. Ideal for detailed parts.
- HTV silicones – Withstand over 200°C. Can be cast with metal alloys. Require special 3D printers.
- Medical grade silicones – Meet FDA and ISO biocompatibility standards. Used for medical devices and wearables.
- Composite silicones – Mixed with fillers like aluminum, silicon carbide, and carbon fiber to enhance properties.
- Flexible/rigid silicones – Tunable materials from Shore 10A to 70D hardness. Used to alter flexibility, durability.
- Custom formulated silicones – Materials can be optimized for different 3D printing processes and applications.
Silicone resin producers like Wacker, Dow Chemical, and Shin-Etsu offer specialized 3D printing grades. Custom silicone development is also done by 3D printer OEMs like Formlabs and Stratasys.
As material options expand, designers can dial in specific properties needed for their silicone 3D printed parts.
Key Silicone 3D Printer Manufacturers
A range of 3D printing companies currently produce silicone printers or are developing models to be launched commercially:
- Formlabs – Offers the Form 3B SLA printer and Elastic Resin for flexible, surgical-grade silicone parts.
- Stratasys – Their J7 DentaJet printer utilizes a proprietary triple jetting technology to 3D print colored, multi-material silicone parts.
- Wacker – Collaborates with multiple 3D printer makers like BigRep and Creatbot to develop material extrusion printers and silicones like Elastosil LR 3654.
- Proto Labs – Acquired silicone printer manufacturer Axiom to provide material jetting-based silicone printing services.
- Carbon – Their L1 printer leverages digital light synthesis technology for production-grade silicone parts.
- BD – This medical company developed the TissueFab system for bioprinting silicone scaffolds combined with living cells.
- Pollen AM – Uses an innovative resin delivery system in their Matrix printer for high quality silicone parts.
- 3D Systems – Feature silicone-like materials for the Figure 4 and ProJet MJP 3D printers.
As major material suppliers like Dow Chemical and Wacker continue advancing specialized silicone grades for 3D printing, adoption of silicone printers is projected to grow significantly.
The Future Outlook for Silicone 3D Printing
Silicone 3D printing is still in a nascent stage, with active material and hardware developments underway to improve print quality, part functionality, and material capabilities. As these advancements happen, adoption is expected to accelerate.
Here are some key trends that will shape silicone 3D printing’s future:
- New 3D printer models – Desktop, industrial, and large format silicone 3D printers will continue being launched, expanding options.
- Hybrid printing – Combining silicone with rigid plastics and metals in one print will enable multi-material components.
- Tunable properties – More grades will provide control over shore hardness, tear strength, temperature resistance, and other attributes.
- Simulation software – Modeling how silicone behaves during printing and post-processing will optimize part designs.
- Manufacturing automation – Print farms of silicone 3D printers will enable mass customization and large production volumes.
- Bioprinting integration – Printing silicone scaffolds with living cells will create tissues and organ models for medical research.
- Micro 3D printing – High resolution methods like two-photon polymerization will 3D print micron-scale silicone structures.
As material options grow, printers advance, and designers gain experience with leveraging its properties, silicone 3D printing will transform everything from medical devices to consumer products that demand soft, flexible, and customized rubbery parts.
Silicone’s unique fluidity, elasticity, and biocompatibility simply cannot be replicated using traditional plastics and metal alloys. The rise of accessible silicone 3D printing technologies will open up a new universe of applications and design possibilities still waiting to be discovered across industries.
