Located in Burlington, Massachusetts, 3D printing company Digital Alloys is bringing something brand new to the table. It’s called Joule Printing, and the company claims it will bring metal 3D printing into the mainstream. Although metal 3D printing is becoming more common as costs lower and technologies diversify, it still has its issues, including still-high production costs, slow printing speeds, complexity, and quality issues.
“Current methods take too long to be practical, or require the use of dangerous materials, specialized hardware, and multiple complex finishing steps involving shrink compensation software, chemical baths, and furnaces,” says Digital Alloys CEO Duncan McCallum. “Look past the hype around metal 3d printing, and you’ll find it’s rarely used in production.”
These challenges, says Digital Alloys, are circumvented by Joule Printing, a wire-feed additive manufacturing process that does not require any sort of metal powder. It works with any metal in wire form, and involves the tip of the wire being positioned in the desired printing location. The system then pushes current through the wire and into the print bed. The current melts the wire using joule heating, also known as resistance heating, which is the same method that heats a toaster coil. The process continues as the print head moves across the bed, laying down beads of metal which are fused together to form fully dense metal parts.
The positioning and melting of the wire occur in a single step, which lowers cost, saves time and increases repeatability. Joule heating, according to Digital Alloys, is the most efficient way to convert electrical energy into heat. Because the wire melts from within, there is no need to wait for the heat to move to where it’s needed. Melting occurs instantly at the desired location, which will allow Digital Alloys’ system to print at 5-10 kg per hour at very low power.
“Joule Printing™ provides precise closed-loop control of melting at the voxel level,” continues McCallum. “Since the wire is held in a precision motion system, we know exactly where the melt is deposited. Unlike a direct energy deposition system, there is no dripping or splashing. We use the precision wire feed system to measure and control how much metal goes into the melt pool. The electric circuit provides measurement and control of how much energy is applied to the melt. This combination of tightly controllable process parameters allows the system to deliver consistently dense (99.5%+) isotropic parts that are stronger than castings. In addition, the process data for every voxel is saved for post analysis. In combination with our machine learning technology, this provides the capability for non-destructive QA of printed parts.”
Digital Alloys was formed last year as a spin-out from NVBOTS, and today announced that it has completed its Series B financing, supported by:
“Our investment in Digital Alloys will help Boeing produce metal structural aerospace parts faster and at higher volume than ever before,” said Brian Schettler, managing director of Boeing HorizonX Ventures. “By investing in companies with emerging additive manufacturing technologies, we aim to strengthen Boeing’s expertise and help accelerate the design and manufacture of 3D-printed parts to transform production systems and products.”
Digital Alloys was also awarded its first two patents on Joule Printing. The technology is capable of 3D printing with multiple metals in one part, and offers higher resolution than other wire-based 3D printing technologies, according to the company.
3DPrint.com spoke with Duncan McCallum the CEO of DigitalAlloys about their technology,
Duncan said that, “the initial application area for our technology is for parts sized between a baseball and a beach ball. Our raw material and machine-hour costs are lower than alternative technologies. We’re current printing at one kilogram per hour, with a plan to exceed 5 kg per hour by the end of the year.”
This means that Digital Alloys is already a sea change faster than current generation metal 3D printing speeds. By staying away from crowns and small implants, the traditional stomping ground of powder bed fusion and focusing on larger less expensive parts they may find and exploit their own market. He said that, “Powder Bed Fusion is too slow and the powder too expensive. Wire DED type technologies are fine for large parts but too sloppy for fine ones. We see ourselves as in between these technologies.” That is a wide application area to be in and may make them cost-effective and usable for automotive and larger aerospace parts. In terms of costs there are also significant advantages. Digital Alloys claims that next to no post processing has to be done with their technology but they can make near net shape 99.5% dense parts without post processing. So without destressing, debinding and other costly steps the time to part will be much faster. The cost per part will also be significantly lower as well.
Duncan stated that, “Our process does not require HIP or other post-processing techniques this significantly lowers cost as well. Our wire feedstock is also much less expensive than other 3D printing materials. Overall we have significant cost advantages over existing technologies. We aim to produce parts at 25-50% less cost than conventional manufacturing, particularly for parts that are made from metals that are hard to cut such as titanium, tool steel, and inconel.
By exactly feeding in a material and knowing precisely at which Voxel that material is we can heat it quicker. It forms a circuit and that’s how we can feed in the material precisely into the melt pool and control the melt pool. By doing this we have good control over microstructures and the final part.” This is quite the claim. If Digital Alloys can deliver on reliability and repeatability then they may have a very exciting manufacturing technology on their hands. Want to try it out? Before launching their machine the company will be acting as a service. If you’re curious as to what geometries are possible and what the pricing is you can contact them to find out more. They already will produce parts for a dozen clients by the end of the year.
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