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Emerging UV Curing Applications in Additive Manufacturing

By Dianna Brodine, managing editor

UV+EB Technology

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Patented Technology

Method and apparatus for continuous composite three-dimensional printing 
Patent No. US 9511543 B2
Granted to Kenneth Tyler, December 6, 2016

ABSTRACT: A method and apparatus for the additive manufacturing of three-dimensional objects are disclosed. Two or more materials are extruded simultaneously as a composite, with at least one material in liquid form and at least one material in a solid continuous strand completely encased within the liquid material. A means of curing the liquid material after extrusion hardens the composite. A part is constructed using a series of extruded composite paths. The strand material within the composite contains specific chemical, mechanical or electrical characteristics that instill the object with enhanced capabilities not possible with only one material.

At the RadTech 2016 awards dinner, creative users of UV/EB technologies were honored with Emerging Technology Awards. One of the 2016 honorees was Continuous Composites (CC3D), a Coeur d’Alene, Idaho-based company that has developed a 3D printing process to print continuous fiber with UV-curable resin. CC3D is reportedly the only company in the world 3D printing continuous fiber with thermoset epoxy and the only company to successfully print continuous fiber into free space. With a focus on functional composites additive manufacturing to scale, CC3D is providing an industrial solution to advanced manufacturing techniques of mid- to large scale.

Adding strength and flexibility

Ken Tyler is the chief technology officer for Continuous Composites and inventor of the foundational technology. Originally a craftsman in the boat industry, Tyler first used a stereolithography (SLA) machine at a rapid prototyping center at Boise State University and later witnessed a fused deposition modeling (FDM) machine in action. “The first time I watched one of the FDM machines melting plastics together, I thought it was crude – there had to be a better way,” he explained. “In the boat industry, I was working with epoxies and fiberglass every day, and one day I had an epiphany that we should introduce these materials to the additive manufacturing industry.”

Tyler Alvarado is Continuous Composites’ chief executive officer. “I’ve been partners with Ken for two years now,” he said. “When we met, Continuous Composites was a patent-pending technology with limited resources, and it made sense for the me and my business partners to invest in the technology and work with Ken to bring it to the next level.

“There are three primary elements to our technology – materials (i.e., resins and fibers), software and hardware,” Alvarado continued. “Until recently, we had been using the same UV-curable resin for all the various fibers we’ve printed with – it was a one-size-fits-all approach. Now, we’re developing specialized UV-curable formulations for each fiber and/or application – fiberglass, carbon fiber, etc. Our technology has applications across many different industries, and those applications each have their own material requirements.”

“Early on in the technology development, the resin had been the missing piece,” said Tyler. “None of the resins I could find would work with our process, so I attended a conference held by RadTech International North America, where I met a great group of formulators. I had a breakthrough on the resin with them.”

The Continuous Composites process uses low-viscosity, UV-curable thermoset resins as opposed to the thermoplastics that are used in conventional 3D printing. With thermoset resins, there is no heating and cooling process like there is with thermoplastics. The thermoset resin is extruded with the continuous fiber – ranging from carbon fiber and fiberglass to fiber optics and copper wire – to form a part with properties unavailable with traditional 3D printing. “Our thermoset resins are cured using UV light, which causes a molecular-level change, and the parts cure without porosity” Alvarado said. “The UV curing process not only ‘sets’ the resin quickly, but also enables us to print into free space without supports.”

He continued, “This allows us to orient fibers in unique ways to reinforce stress points and not deposit materials where materials are not needed. Our technology opens up the realm of design and manufacturing capabilities. We no longer need molds and autoclaves to manufacture composite structures.”

High material deposition also is a major benefit of the technology. Continuous Composites has the ability to not only print with single nozzles extruding a single tow of fiber, but also multi-channel nozzles with multiple tows of fiber – often different types of fibers – simultaneously. “We’ve always had a plan to put our print head on a robot arm, but it’s currently on a gantry system,” said Alvarado. “We’re designing and manufacturing a 4th and 5th axis to act as a ‘wrist’ to angle and rotate the nozzle(s) which expands our motion control capabilities.”

Taking the technology to industry

“I filed the first patent for the technology in 2012, and it was granted in December of 2016,” said Tyler (see sidebar).

“Now, we are working to license our technology to companies from various industries,” Alvarado continued. “We are having good discussions with major players from industries such as automotive, aerospace and construction.”

In addition to the uniqueness of the fiber/resin combination, low energy usage and higher speeds are attracting attention. “We are focusing UV LEDs at the point of extrusion, so we’re able to apply really high energy – as high as 14 watts per cm2 – but we’re not consuming much power, because LEDs have low power usage,” Tyler explained. “And, we can cure up to 1,500 inches per minute.”

Alvarado’s vision for the technology is impressive. “We’ve been able to showcase our technology’s ability to print strong composite parts unsupported in free space while embedding other functional materials, such as fiber-optics and copper wire. As our technology matures, we will be printing production-ready parts quickly, which will include sensors and other electronic components,” he said. “It’s not hard to see a future where the technology allows us to print an entire airplane.”

As for Tyler, his goal for the technology leads back to where he first had the idea that sparked Continuous Composites. “One of these days, I’ll be able to 3D print my own boat,” he laughed.