Silicone additive manufacturing (SAM) is an incredible niche area of 3D printing that has only really started to pick up steam in the last couple of years. The rubber-like elastomer is usually great for use in sealants, adhesives, and lubricants, owing to its excellent elasticity. Therefore, 3D printing the material can add another dimension to functional prototyping, whereby several parts in an assembly can be consolidated by co-extruding a silicone raw material between them.
True silicone is also 100% biocompatible, making it a fantastic choice for personalized medical devices. Unlike traditional silicone manufacturing methods like injection molding or casting, 3D printing grants an unmatched level of geometric freedom, so implants, wearables, and prosthetics can be tailored to the anatomy of the patient for improved efficacy and comfort.
Silicone additive manufacturing with ACEO
Arguably the biggest player in the SAM space is ACEO, the silicone 3D printing arm of German chemical giant WACKER. The company’s proprietary technology is based on drop-on-demand material jetting, where a curable silicone liquid is deposited out of a nozzle to form 3D shapes.
The key consideration here is that once the silicone solidifies, it does not revert to its liquid state, so the final objects are – just like traditionally produced silicone parts – heat resistant and hold their shapes. The precision of the process is also noteworthy, as layers can be drawn out down to just a fraction of a millimeter, allowing for extremely precise silicone components.
In addition to the printing technology, ACEO also provides its own portfolio of silicone 3D printing materials. The silicone line contains Shore A hardness from 20 all the way to 60, with 50 Shore A being the real silicone elastomer. It is intended for high-performance applications in typical silicone industries such as automotive, aerospace & aviation, healthcare, and manufacturing.
The company also offers a special grade of silicones that is electrically conductive and can be used in multi-material prints to provide conductivity and resistance for electrical components such as heat pads, with a full suite of colours no less.
The UK debut with Spectroplast
The Digital Manufacturing Centre (DMC), an upcoming 3D printing service provider created by engineering firm KW Special Projects, recently became the first to offer SAM in the UK. The technology now being offered was developed by Spectroplast, a spin-out from ETH Zurich.
Unlike ACEO’s material jetting method, Spectroplast’s technique works a lot like resin-based SLA technologies, in that liquid silicone is exposed to a concentrated light source, curing it into solid layers. The final parts are reportedly just as strong as those manufactured via the more conventional methods and have equivalent surface finishes.
Since the technology doesn’t require any tooling, it enables end-use parts with minimal waste and lead times. If the company’s claims are anything to go by, the 3D printing method is capable of cutting lead times down from six weeks to just five days. As such, it also reduces the overall cost per part by as much as 50% when considering certain production volumes. Much like ACEO, Spectroplast’s material range varies from Shore Hardness A20 to A60, with temperature resistances going from -50°C to 200°C.
Taking an antibacterial approach
Silicone 3D printing materials can also be further functionalized with a range of non-mechanical properties, such as antibacterial functionality. STERNE, an industrial silicone manufacturer from France, has previously turned this idea into a product perfect for the 3D printing of medical devices.
Back in 2019, the company released an antimicrobial silicone material that resists the formation of bacteria both in and outside of a 3D printed part. Developed for use with the company’s SiO-Shaping system, which combines material deposition with UV curing, the material enables 3D printed medical products with resistances and mechanical properties identical to those of comparable injection-molded parts.
So, it’s clear then that the silicone 3D printing market isn’t exactly saturated. While the number of silicone system manufacturers can probably be counted on one hand, they each do a fairly good job of maintaining their respective corners. Despite the infancy of the technology, it is already being offered by big-time service bureaus for medical device production, as well as for general engineering applications such as gaskets, seals, and dampers. Since the technology has very recently spread to the UK, we can expect to see a number of challengers rise up in the coming years in a bid to capitalize on this underdeveloped sector.