ETEC
Within the complex field of 3D printing technologies, Digital Light Processing or DLP is easily one of the most simple, mature, and popular methods available for polymer parts manufacturing.
DLP harnesses the power of light from an area-wide projector to cure photosensitive liquid resins into parts layer by layer, one quick flash at a time — delivering smooth, accurate parts in a fraction of the time of laser-based stereolithography, or SLA, which must draw out part designs individually.
Over its 20-plus years of existence the DLP process has largely been executed in the same way: a video projector is stationed below a vat of photosensitive resin, and print jobs are built as a job advances vertically out of the vat attached to a build plate. While the field has enjoyed many advancements, most have been incremental in nature and focused on limiting the detrimental separation forces inherent to building parts bottom-up.
As global manufacturers begin to utilise 3D printing for the production of functional end-use parts, there is a requirement to print larger batch sizes, bigger parts and engineered polymers. These requirements shine the spotlight on the limitations of bottom-up DLP.
For one, there’s a limit to how many parts and how much weight can be suspended vertically from a build plate when printing with a bottom-up projector. More importantly, this printing approach forces serious constraints on the types of resins that can be used. Because the resin in the bottom-up DLP printing approach must flow back under the build plate easily and quickly during recoating, it must be a relatively low viscosity. This ultimately limits the final material properties the
resin can deliver, or requires two-part resins that must be mixed together then quickly printed before they spoil.
The fact that the market has not yet produced a robust approach for top-down DLP printers is interesting given that SLA 3D printers, the precursor process to DLP, have long offered a healthy commercial market for both bottom-up and top-down designs. Bottom-up styles are often featured in more affordable desktop units while industrial models often deploy the top-down approach.
Now, ETEC is embarking on this more industrial approach to DLP with the Xtreme 8K. Aside from holding the distinction as the world’s largest production-grade DLP printer, the Xtreme 8K is also one of the industry’s only top-down DLP printers — two features that are, as it turns out, highly interconnected. Most importantly to users, it provides an extremely large build area and better material properties without sacrificing surface quality and part accuracy.
This cutting-edge DLP machine, first revealed in 2021, features two industrial overhead projectors stationed above the resin vat. This allows the Xtreme 8K to offer the largest DLP build area — 166,950 mm2 (450 x 371 x 399 mm) — among commerciallyavailable, production-grade DLP printers. Additionally, two intense and direct light sources that don’t have to penetrate through a vat film or tray enable new materials with higher energy requirements for curing.
This innovative machine design has unlocked the ability to produce large parts and manufacture in high-volumes with DLP 3D printing as well as process new materials that directly compete with thermoplastics used in traditional plastic injection moulding.
ETEC
XTREME 8K DLP
A BREAKTHROUGH NEW CATEGORY OF PHOTOPOLYMERS
Many of the initial low-viscosity photopolymer resins used in vat photopolymerisation – whether DLP or SLA – were derived from the protective coatings industry, where they were applied in ultra-thin layers and then cured with UV lights.
During curing, the materials are crosslinked, or chemically bonded to form a polymer. While these early photopolymer resins rapidly cure and offer good surface finish, they tend to be brittle and prone to cracking and shattering, offering poor impact resistance and little of the toughness and resilience needed to compete with today’s traditionally manufactured plastics. Their performance also tends to degrade over time or as parts are exposed to light and hot or cold temperatures.
For decades, the field of polymer AM has been working to enhance the material properties to overcome these hurdles and deliver more resilient, elastomeric properties.
DuraChain is a new category of materials invented by Adaptive3D, a subsidiary of Desktop Metal, to solve these problems. Adaptive3D developed a proprietary and unique blend of materials that takes advantage of a specific chemical reaction process, called Photo Polymerization-Induced Phase Separation, or Photo PIPS, to deliver all-new material properties in DLP.
When exposed to light during DLP printing, DuraChain photopolymer resins phase separate at the nano level as they cure into a resilient, highperformance network much like legacy two-part material systems that have a shorter pot life. One of the challenges in printing these materials is that they contain high-viscosity base oligomers — similar to honey or molasses — and miscible monomers that would not be easy to process on bottom-up DLP systems, which require more free-flowing resins.
Ultimately, this groundbreaking portfolio of photo-elastomers is finally delivering the tough and resilient properties that the market requires — with high tear strength, elongation, and toughness. What’s more, this unique approach is delivered in a one-part, pot-stable chemistry. Because these materials are so viscous they currently require a top-down DLP printer for processing.
Today, DuraChain resins, which includes all the materials listed below, are printable exclusively on the ETEC Xtreme 8K:
Elastic ToughRubber 90 (ETR 90)
– The toughest AM elastomer on the market. ETR 90 can already be found in parts and products that are sold on store shelves. It is perfect for shoe midsoles and heel cups, seals, door boots, bellows, foam-like lattice structures and impact parts.
Elastic ToughRubber 70 (ETR 70)
– A softer, stretchier ToughRubber useful when printing resolution limits of individual struts and minimum feature sizes do not allow ETR 90 to achieve the requisite soft feel via microarchitecture alone.
Soft ToughRubber (STR)
– Designed for functional prototypes of audio earbuds, wearable electronics, and anatomical medical models, Soft ToughRubber (STR) delivers a silicone feel and mechanical properties with the resolution and surface finish that DLP printing provides.
FreeFoam
– A new family of photopolymer resins containing a heat-activated foaming agent. After printing a design in FreeFoam, the part is expanded during foaming in an oven, creating a closed-cell foam with tight dimensional accuracy, and customisable for a variety of Shore A hardness values.
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