Can you 3D print silicone?

As 3D printing has continued to revolutionize the manufacturing industry, enabling the creation of complex and customized objects with relative ease, one of the materials that has been of interest is silicone. Silicones are polymers based on polymerized siloxanes and are known for their rubber-like properties, as well as good thermal stability and chemical resistance, biocompatibility, water tightness, environmental hardiness, and electrical insulation. This roster of properties has led to silicones being used for a wide variety of applications, from cooking utensils, to aircraft seals, to electrical coatings, to medical implants.[1] 

Despite their widespread adoption using more conventional manufacturing processes, silicones are notoriously challenging materials to 3D print. This is largely due to the fact that silicone is an elastomer. Unlike thermoplastics which can be melted and returned to a solid state, elastomers cannot be melted down once they are solidified. This has excluded many forms of 3D printing—such as fused filament fabrication (FFF)—from the possibility of 3D printing silicones.

Even so, it is possible to 3D print silicone-based materials and there are a number of solutions that exist on the market today for silicone 3D printing. We’ll explore the topic in further detail below, discussing silicone’s properties, how silicone 3D printing works, applications for the technology, and the pros and cons of silicone 3D printing. 

Properties of Silicone

Silicone is a synthetic material made from silicon, oxygen, carbon, and hydrogen. It is a versatile and unique material due to its combination of properties, which make it suitable for a wide range of applications. Some of the key properties of silicone include:

• Thermal stability: Silicone can withstand a wide temperature range, typically from -60°C to 230°C. Some specialized silicones can even endure temperatures up to 300°C. This thermal stability makes silicone an ideal material for applications that require resistance to extreme temperatures, such as gaskets and seals in automotive and aerospace industries.

• Flexibility and elasticity: Silicone is known for its flexibility and elasticity, allowing it to stretch and deform without losing its original shape. This property is particularly useful in applications where the material needs to accommodate movement or stress, such as medical devices and wearable technology.

• Chemical resistance: Silicone is resistant to many chemicals, including oils, acids, and alkalis. This chemical resistance makes it suitable for use in harsh environments where other materials might degrade or fail.

• Electrical insulation: Silicone is an excellent electrical insulator, making it a popular choice for applications requiring electrical insulation, such as cable sheathing and electronic components.

• Biocompatibility: Many silicones are biocompatible, meaning they do not cause adverse reactions when in contact with living tissue. This property makes silicone an ideal material for medical applications, such as implants and prosthetics.

• Low toxicity and low odor: Silicone is generally considered to be low in toxicity and has minimal odor, making it a suitable material for use in consumer products, such as kitchenware and personal care items.

3D Printing Silicone: Methods and Techniques

While traditional 3D printing technologies like FDM, SLA, and SLS are not directly compatible with silicone, there are specialized methods and techniques developed specifically for 3D printing silicone. These methods address the unique properties and challenges of working with silicone materials, such as their viscosity and curing behavior. In this section, we will discuss some of the existing methods and techniques used for 3D printing silicone.

Earbuds made from silicone

Silicone Deposition

One approach to silicone 3D printing is silicone deposition, which bears some similarities to FFF. However, unlike FFF, which uses a heated printhead to extrude layers of melted thermoplastics onto a print bed—which then solidify as they cool—silicone deposition 3D printing does not involve any heating process. Instead, a print head deposits droplets of liquid silicone onto a print bed and a curing method is used to harden the droplets. 

ACEO, a company owned by Wacker Chemie AG, pioneered a deposition-based 3D printer that used a print head to dose single droplets of a silicone-based 3D printing material onto a build platform. These droplets were then cured using UV light (when it comes to silicones, the curing process is also called vulcanization), which solidified the droplets by creating crosslinks. Parts were built up in this fashion—dosing and curing—layer by layer. This technology also integrated several printheads, enabling multi-material silicone printing as well as the use of removable supports for achieving more complex geometries.[2] At the end of 2021, however, Wacker Chemie shut down ACEO’s 3D printing service, saying the following: “As for most new inventions, it takes more time for the market to develop as we have initially expected.” [3]

There is another deposition approach that was introduced by InnovatiQ (formerly German RepRap). The technology, called Liquid Additive Manufacturing (LAM), is described as “an additive manufacturing process in which liquids (or low-strength materials) can be additively processed, such as liquid silicone rubber (LSR).” The LSR material compatible with this process is produced by chemical company Dow. The LAM process uses volumetric extrusion to precisely deposit the liquid silicone material. Curing takes place directly in the build space after every printed layer of material. Using this technology, the curing is achieved using a high-temperature halogen lamp.[4]

Photopolymerization

While most standard stereolithography (SLA) or digital light processing (DLP) technologies are not compatible with silicone-based materials, there are some exceptions. 3D printing company Carbon, for instance, offers a silicone 3D printing capability based on its Digital Light Synthesis (DLS) technology. In 2017, the company launched SIL 30, a silicone urethane material with good tear resistance and biocompatibility that is compatible with DLS. This process uses UV light projections to cure layers of liquid polymer resin. In this technique, the silicone resin material is held in a vat, with layers solidifying as the build platform is raised.[5]

Swiss startup Spectroplast is also another player in the silicone 3D printing area. The company’s patented Silicone Additive Manufacturing (SAM) technology is capable of printing 100% pure silicone materials and is offered through a dedicated 3D printing service. Little more is known about how the process works but Spectroplast has also brought to market TrueSil, a series of ISO-certified silicone materials for 3D printing with a range of Shore A hardnesses.[6] 

Also in this space, Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has developed a range of silicone-based resins that are compatible with DLP 3D printers. DLP is a 3D printing technology that uses a digital projector to selectively cure a photosensitive resin, layer by layer. CSIRO’s resins, first announced in 2021, are reportedly capable of creating highly complex shapes at a high resolution and were developed with medical applications in mind. But don’t expect to pick up these resins from your local resin supplier: the innovative silicone resins have yet to be commercialized. [7]

Recommended reading: 3D printing silicone for breathing apparatus

Silicone Casting

While not a direct 3D printing method, additive manufacturing technologies can be used alongside more conventional manufacturing processes, just as molding and casting. Specifically, it is possible to 3D print molds to accelerate silicone product development or to produce small batch or custom end-use parts. (For mass production applications, metal tools are still the standard.)

Various 3D printing technologies, like FFF and SLA, can be used to print molds for room-temperature-vulcanizing silicone (RTV silicone). There are also different molding techniques that can be achieved using 3D printing, including compression molding, injection molding, and overmolding. Using 3D printing to create molds for silicone can save users time and resources, since it does not require expensive tooling or hardware. For that reason, it’s ideal for rapid prototyping or small production runs. 

Another alternative is 3D printing master patterns to create silicone molds. There are many helpful online guides to follow[8], but the gist is using your 3D printer to create a mold box and your master pattern. You can then pour liquid silicone (mixed with hardener) into the mold box to create a high-quality mold that can be used for manual injection molding. The silicone is a great material for molds because it can easily be removed from the cast part and reused.

Silicone molds can be made using a 3D printed master.

Material Considerations for 3D Printing Silicone

When selecting a silicone material for 3D printing, it is essential to consider various factors that can influence the printing process and the final properties of the printed object. These factors include material properties, such as viscosity and curing time, as well as the specific requirements of the application.

• Viscosity: The viscosity of the silicone material is a crucial factor to consider, as it can affect the deposition or curing process during 3D printing. Materials with low viscosity are more suitable for processes like injection molding or DLP, while materials with higher viscosity are more appropriate for deposition-based methods. It is essential to choose a material with the right viscosity for the chosen 3D printing method to ensure smooth material flow and proper layer adhesion.

• Curing time and conditions: The curing time and conditions of the silicone material can also impact the 3D printing process. Materials with a faster curing time may be more challenging to work with, as they can solidify before the printing process is complete. On the other hand, materials with a slower curing time may require additional post-processing to achieve their final properties.

• Mechanical properties: The mechanical properties of the silicone material, such as hardness, tensile strength, and elongation, should be considered based on the intended application of the printed object. For example, a flexible and soft silicone material may be more suitable for wearable devices or medical applications, while a harder and more durable material may be more appropriate for automotive, robotics, or aerospace components.

• Biocompatibility and chemical resistance: For applications that involve contact with living tissue or exposure to harsh chemicals, it is crucial to use a silicone material with the appropriate biocompatibility and chemical resistance. Some silicone materials are specifically designed for medical applications and have been tested for biocompatibility, while others may have enhanced chemical resistance for use in aggressive environments.

• Cost and availability: The cost and availability of the silicone material should also be considered, as some materials may be more expensive or harder to source than others. It is essential to balance the material properties and requirements of the application with the cost and availability of the silicone material to ensure a successful 3D printing project.

Advantages and Challenges of 3D printing Silicone

Like any material, there are pros and cons to 3D printing silicone elastomers. Let’s take a look at some of the material’s main advantages as well as the challenges that still face this niche segment of the 3D printing industry.

Advantages of 3D Printing Silicone

• Material properties: Some of the main advantages of silicone in 3D printing are related to the material’s properties, including its unique combination of strength and flexibility, temperature and chemical resistance, biocompatibility, and electrical insulation. Of course, these advantages are available using traditional production methods and are not strictly limited to 3D printing

• Design freedom: 3D printing opens up new opportunities for design freedom when it comes to silicone parts. Unlike more traditional processes like injection molding, the technology is capable of creating complex geometries, with internal structures, such as lattices.

• Streamlined production: Silicone 3D printing also enhances the product development process by enabling rapid prototyping and cutting back on prototyping costs. In other words, product developers and engineers can rapidly iterate silicone prototypes, test them, make necessary adjustments, and reiterate until the design is perfect.

• Customization: With 3D printing, manufacturers can cost-effectively produce customized products made from silicone. This is particularly important in the medical field, where custom medical aids or devices can be made based on patient specifications.

• Part quality: Silicone 3D prints are generally known for their good quality finishes. In some cases, support material removal and additional curing to further solidify the silicone part may be necessary, but extensive post-processing is not generally required because of good surface finish quality.

Challenges of 3D Printing Silicone

While silicone offers numerous advantages for various applications, there are also challenges associated with 3D printing silicone. Some of the key challenges include:

• Technology availability: Silicone 3D printing is still very much a niche process, and has yet to become a widely available solution for silicone production. Today, most processes are available only through a dedicated service, which limits who can access the technology.

• Size limitations: In its current state, silicone 3D printing also has limitations in terms of what types of parts it can create. Silicone 3D printing systems on the market have small build volumes and are thus not well-suited for the production of large-scale parts. This inevitably limits the prototyping and production applications for silicone 3D printing.

• Lack of standards: Another consequence of being such a relatively fringe technology, is that silicone 3D printing has few standards and documentation associated with it. Of course, this challenge is not as critical for prototyping applications and it will be addressed as the technology continues to advance and adoption increases.

• Limited material options: While there are various types of silicone materials available, the range of materials specifically designed for 3D printing is more limited compared to other materials like plastics or metals. 

• Curing process: The curing process of silicone materials can require precise control over factors such as temperature, humidity, and exposure to UV light. Incomplete or uneven curing can result in parts with inconsistent mechanical properties. It is crucial to understand the specific curing requirements of the chosen silicone material and ensure that the 3D printing process and post-processing steps are optimized accordingly.

Recommended reading: Why 3D Print?

Applications of 3D Printed Silicone

Just as there are many applications for silicone materials, there are many opportunities for 3D printing silicone. Because 3D printing is well suited for one-off or small batch production, mass manufacturing of silicone products is still best left to traditional injection molding techniques. The big opportunity for 3D printing silicone applications therefore lies in the production of functional prototypes, custom parts, or small production batches, which would not be economically viable using injection molding.

Today, we see silicone 3D printing used in many industries, from medical to aerospace. Let’s take a closer look. 

Medical and Dental

The medical and dental industries are among the most interested in silicone 3D printing capabilities. This is because silicone is a non-toxic, biocompatible material and 3D printing enables the production of patient-specific products. For example, silicone 3D printing can be used in the production of custom anatomical models (based on patient CT scans), which can improve pre-surgical preparation. Silicone is particularly interesting in these cases because of its transparent properties, allowing surgeons to visualize internal anatomical structures. 

In healthcare, silicone 3D printing also has potential to be used in the production of soft prosthetics, such as ears and noses, thanks to its flexible, soft texture. These properties are also useful in dentistry, where silicone 3D printing can create soft gum and gingiva models to complement dental models and devices made using hard materials on DLP or SLA platforms.

3D printed silicone medical components made by Spectroplast (Image: Spectroplast)

Some examples of medical and healthcare applications for 3D printed silicone include:

• Prosthetics and orthotics: 3D printed silicone can be used to create customized prosthetic and orthotic devices, such as sockets, liners, and cushions. The flexibility and comfort of silicone make it an ideal material for these applications, as it can conform to the patient's anatomy and provide a comfortable fit.

• Surgical guides and models: 3D printed silicone can be used to create accurate anatomical models and surgical guides, helping surgeons plan and practice complex procedures. The material's transparency and flexibility allow for a realistic representation of soft tissues, enabling better visualization and understanding of the surgical site.

• Implantable devices: Silicone's biocompatibility and durability make it suitable for implantable devices, such as cochlear implants, pacemaker lead insulators, and hydrocephalus shunts. 3D printing allows for the customization of these devices to fit the patient's specific needs and anatomy, potentially improving the device's performance and patient outcomes.

• Respiratory masks and nasal prongs: 3D printed silicone can be used to create customized respiratory masks and nasal prongs, providing a comfortable and secure fit for patients who require respiratory support. The material's flexibility and softness help reduce pressure points and skin irritation, improving patient comfort and compliance.

Automotive and Aerospace

3D printed silicone also has big potential in the automotive and aerospace industries, where the material’s unique properties, such as thermal stability, chemical resistance, and durability, are highly valued. 3D printed silicone also offers unique advantages for robotic and industrial applications. For instance, the flexible yet durable material is ideal for soft robotic components. 3D printing enables engineers to design complex prototypes or end-use components, such as grippers or pneumatic actuators, for soft robots. Because of silicone’s electrical properties, the material is also well suited for prototyping or customizing electrical enclosures. 

Some examples of automotive and aerospace applications for 3D printed silicone include:

• Gaskets and seals: 3D printed silicone can be used to create custom gaskets and seals for various automotive and aerospace components, such as engines, transmissions, and fuel systems. The material's thermal stability and chemical resistance make it suitable for use in harsh environments, while its flexibility ensures a tight seal and prevents leaks.

• Vibration damping and isolation: Silicone's flexibility and elasticity make it an excellent material for vibration damping and isolation applications. 3D printed silicone components can be used to reduce vibrations and noise in automotive and aerospace systems, such as engines, gearboxes, and avionics, improving performance and comfort for passengers and crew.

• Electrical insulation and connectors: The electrical insulation properties of silicone make it suitable for use in automotive and aerospace electrical systems, such as wiring harnesses, connectors, and insulators. 3D printed silicone components can provide protection against electrical shorts and arcing, ensuring the reliability and safety of critical systems.

• High-temperature components: Silicone's ability to withstand high temperatures makes it an ideal material for components exposed to extreme heat, such as exhaust systems, engine components, and thermal insulation. 3D printed silicone parts can maintain their mechanical properties and resist degradation under high-temperature conditions, ensuring the durability and performance of these critical components.

Consumer Products

3D printed silicone has a variety of applications in the consumer products sector, where its flexibility, durability, and low toxicity make it an attractive material for a wide range of products. Silicone’s biocompatibility and flexible material properties are also advantageous in the consumer goods sector. For instance, 3D printing is used to produce customized products that come into contact with skin, such as earbud adapters for earphones, headphone pads, and more. 

Some examples of consumer products that can benefit from 3D printed silicone include:

• Wearable devices: Silicone's flexibility and comfort make it an ideal material for wearable devices, such as smartwatches, fitness trackers, and medical monitoring devices. 3D printed silicone bands and casings can be customized to fit the user's wrist and provide a comfortable, secure fit.

• Kitchenware and utensils: Silicone's heat resistance, non-stick properties, and low toxicity make it a popular material for kitchenware and utensils, such as spatulas, baking mats, and molds. 3D printed silicone kitchenware can be customized to create unique shapes and designs, adding a personal touch to the user's kitchen.

• Personal care products: Silicone is often used in personal care products, such as toothbrushes, facial cleansing brushes, and hair styling tools, due to its softness, flexibility, and low toxicity. 3D printed silicone components can be tailored to the user's needs and preferences, ensuring a comfortable and effective user experience.

• Protective cases and covers: Silicone's durability and shock-absorbing properties make it an excellent material for protective cases and covers for electronic devices, such as smartphones, tablets, and laptops. 3D printed silicone cases can be customized to fit the specific dimensions of the device and provide a secure, protective barrier against drops, scratches, and impacts.

• Toys and games: Silicone's softness, flexibility, and low toxicity make it a suitable material for toys and games, especially for young children. 3D printed silicone toys can be designed with unique shapes, textures, and colors, providing a safe and engaging play experience for children.

Recommended reading: What is TPU Material in 3D printing: material properties, applications, and technologies

Additional Information on Silicone

Understanding more about silicone materials can also help give you a deeper understanding of where 3D printing fits in to silicone manufacturing more generally. In this section, we’re covering the different types of silicone that exist and the material group’s pros and cons.

Types of silicone

There are several types of silicone, each with its unique properties and applications. Some of the most common types include:

• High Consistency Rubber (HCR): HCR is a solid silicone rubber that comes in various hardness levels, typically measured on the Shore A scale. HCR is known for its excellent mechanical properties, such as tensile strength and tear resistance. It is commonly used in applications like seals, gaskets, and automotive components.

• Liquid Silicone Rubber (LSR): LSR is a two-component, pourable silicone material that cures into a flexible and durable rubber. LSR has a low viscosity, making it suitable for injection molding and other processes that require precise control over material flow. LSR is often used in medical devices, such as catheters and respiratory masks, due to its biocompatibility and ability to create complex shapes.

• Room Temperature Vulcanizing (RTV) Silicone: RTV silicone is a one- or two-component material that cures at room temperature, forming a flexible rubber. RTV silicone is available in various hardness levels and can be used for applications like mold making, encapsulation, and sealing. Its ease of use and ability to cure without heat make it popular for DIY projects and small-scale production.

• Silicone Gels: Silicone gels are soft, highly flexible materials with a gel-like consistency. They are known for their excellent cushioning and shock absorption properties, making them suitable for applications like electronics encapsulation and medical implants. Silicone gels can also be used for vibration damping and thermal management in various industries.

• Silicone Foams: Silicone foams are lightweight, open-cell materials that provide excellent thermal and acoustic insulation. They are commonly used in applications like automotive and aerospace insulation, gasketing, and cushioning. Silicone foams can be produced in various densities and hardness levels to meet specific requirements.

• Silicone Resins: Silicone resins are highly crosslinked polymers that form rigid, glass-like materials when cured. They are known for their excellent thermal stability, chemical resistance, and electrical insulation properties. Silicone resins are often used in applications like coatings, adhesives, and encapsulants for electronics and high-temperature environments.

Advantages and Disadvantages of Silicone

Silicone offers several advantages and disadvantages, depending on the specific application and requirements. Here, we will discuss some of the key benefits and drawbacks of using silicone.

Advantages:

• Wide temperature range: As mentioned earlier, silicone can withstand a broad range of temperatures, making it suitable for applications that require resistance to extreme heat or cold.

• Flexibility and elasticity: The flexibility and elasticity of silicone allow it to accommodate movement and stress, making it ideal for applications like seals, gaskets, and wearable devices.

• Chemical resistance: Silicone's resistance to various chemicals, including oils, acids, and alkalis, makes it suitable for use in harsh environments where other materials might degrade or fail.

• Electrical insulation: The excellent electrical insulation properties of silicone make it a popular choice for applications requiring electrical insulation, such as cable sheathing and electronic components.

• Biocompatibility: The biocompatibility of many silicones makes them ideal for medical applications, such as implants and prosthetics.

Disadvantages:

• Cost: Silicone is generally more expensive than other materials like rubber or plastic, which can be a limiting factor for some applications, especially in large-scale production.

• Tear strength: While silicone is flexible and elastic, it may have lower tear strength compared to other materials like natural rubber. This can be a disadvantage in applications where high tear resistance is required.

• Adhesion: Silicone has poor adhesion to many substrates, which can be a challenge in applications like bonding or sealing. Specialized adhesives or surface treatments may be necessary to improve adhesion.

• Gas permeability: Silicone is more permeable to gases than other materials like rubber or plastic. This can be a disadvantage in applications where gas barrier properties are essential, such as in vacuum seals or gas-tight enclosures.

• Abrasion resistance: Silicone generally has lower abrasion resistance compared to other materials like rubber or polyurethane. This can be a drawback in applications where the material is subject to wear and tear, such as in seals or gaskets.

Understanding the advantages and disadvantages of silicone is crucial for selecting the most appropriate material for a specific application. It is essential to consider factors like cost, performance requirements, and end-use conditions when choosing silicone as a material for a project.

Conclusion

Though silicone AM is still a nascent and specialized subsegment of the broader additive manufacturing industry, there is enormous potential for the technology. Silicone’s properties offer benefits for a wide range of applications, from medical to automotive, while 3D printing allows for rapid prototyping, customization, and increasingly complex designs. As more silicone 3D printing solutions and materials are developed, and the process is increasingly standardized, adoption and application opportunities will continue to grow.

Frequently Asked Questions (FAQs)

1. Can I use a standard FDM 3D printer to print silicone?

No, FDM printers are not compatible with silicone, however there are some specialized deposition-based technologies that can process silicone materials on-demand.

2. What are the main challenges of 3D printing silicone?

One of the primary challenges of 3D printing silicone is that, unlike thermoplastics which can transition between solid and malleable stages, silicone is hardened permanently. It is also challenging to print large silicone parts, limiting applications for the technology.

3. Is 3D printed silicone biocompatible?

Many silicone materials are biocompatible, making them suitable for medical applications such as implants and prosthetics. However, it is essential to choose a silicone material that has been tested and approved for biocompatibility to ensure the safety and performance of the printed object.

4. Can I 3D print silicone using SLA or SLS technology?

Traditional SLA and SLS technologies are not directly compatible with silicone. However, it is possible to 3D print silicone using Digital Light Processing (DLP), however the silicone resins are not widely available.

5. What are some possible applications of 3D printed silicone?

3D printed silicone has a huge range of potential applications across various industries, including prosthetics and orthotics, surgical guides and models, implantable devices, respiratory masks, gaskets and seals, vibration damping, electrical insulation, high-temperature components, wearable devices, kitchenware, personal care products, protective cases, and toys.

References

[1] https://www.britannica.com/science/silicone

[2] https://www.aceo3d.com/technology/

[3] Sher, Davide. Wacker Chemie to shut down ACEO silicone 3D printing service. VoxelMatters, December 27, 2021. https://www.voxelmatters.com/wacker-chemie-to-shut-down-aceo-silicone-3d-printing-service/ 

[4] LiQ 320. innovatiQ, 2023. https://www.innovatiq.com/en/products/3d-printers/liq-320/ 

[5] Sil 30. Carbon, 2023. https://www.carbon3d.com/materials/sil-30

[6] Silicone Additive Manufacturing. Spectroplast, 2021.  https://spectroplast.com/technology/

[7] 3D Printed Silicones: Creating better silicone resins for 3D printing. CSIRO. https://www.csiro.au/en/work-with-us/ip-commercialisation/Marketplace/3D-printed-silicones

[8] Silicone Molding with 3D Printed Masters. Makerbot, 2023. https://www.makerbot.com/professional/post-processing/silicone-molding-1/