Many users of 3D printing/additive manufacturing technology are concerned with its potential impact on the environment. Often the focus is on resin-based prototypes ending up in landfills and taking years to degrade. But other materials also end up as scrap, such as that from machining and similar subtractive processes.
One company has made it a mission to turn this scrap into usable metal powder for additive manufacturing (AM). The company is 6K Inc. Recently, I had a chance to interview Aaron Bent, CEO at 6K, about how they turn manufacturing scrap into additive manufacturing “gold.”
According to Bent, one factor impeding greater adoption of additive manufacturing is cost. “I think, in actuality, costs and sustainability are intimately linked. In fact, being sustainable can create a very strong business model. And that’s one of our missions here at 6K.”
6K Inc. uses sustainable sources of metal and turns them into high-quality metal powder. These sources include scrap metal, shavings, used parts, and used powder.
While additive manufacturing is typically viewed as being more sustainable than traditional subtractive manufacturing, . . . “If you look at the originating materials, such as a highly engineered alloy ingot, everyone knows that the buy-to-fly ratio is around 10 to one for subtractive manufacturing,” says Bent. “But the dirty little secret of additive manufacturing, unfortunately, is that this ratio is not much better.
“There are two important aspects of sustainability in additive manufacturing. One is that the powder production itself is typically only about a 30% yield, with a lot of the rest of the powder going into landfills. And then the printing process itself has losses that include used powder support structures and non-conforming parts.”
Bent notes that while it is important to address the environmental impact of thermoplastics, it’s also important to focus on the impact of metal powders for two reasons. One, while AM may be relatively small today, it’s going to grow quickly. And by producing powders in a method that offers 100 % yield, versus 30%, means a lot less of those materials find their way into landfills. In addition, it cuts the costs of the energy needed for transportation, mining, and refining of the original ore. So, the impact of metal materials on the environment can be substantial, which affects overall cost.
The company name 6K comes from 6,000 degrees, which is the temperature of the surface of the sun rounded up slightly. “Our microwave-based production plasma operates at 6,000 degrees, which, as you can imagine, can melt anything,” says Bent.
6K’s process begins with certified chemistry materials. These are materials manufacturers use in their machining operations. For example, a large airframe manufacturer may create as many as 100,000 pounds of certified chemistry Ti64 scrap that it can’t otherwise use.
6K can take that scrap, along with support structures from 3D printing, used or previously used powders, and out of spec parts and convert them into suitable powder for AM. “Our mission is to use virtually every part of the additive manufacturing process. And in so doing, we actually create a far better business model for the end customer.”
The “scrap” goes through a two-step process to become a powder. It is cleaned and sized to an engineered feedstock. Then, it goes through the plasma system, which creates exactly the right powder size distribution, whether a customer needs something for metal injection molding, a laser powder bed, an E-beam, or a DED system, the powder size is distributed properly. This methodology helps deliver the 100% yield.
You will find that Bent and his team refer to the powders they create as “inks.” “It’s still just powder,” says Bent. “I think we use ink as a common way to speak and differentiate ourselves as a powder supplier from those making printers. And it’s also a common theme because we can recycle ink. For example, we have had a number of programs with large super-users where we take their used powder that they are not be able to continue using in their printers, and recycle it to make powder that actually performs better than virgin powders.
“We also have programs with a large defense customer that provides us with powders that are not of a quality for 3D printing because they don’t flow sufficiently. So, we “6K” the powder, to use it as a verb. And that provides a higher-performing powder for the printing process. The word ink also is a convenient vernacular when we talk about the ability to provide an infinite palette of colors, in the sense of an infinite variety of different alloys. That’s why we refer to it as ink.
“Virtually anything that is machined can become a feedstock for our powder. In addition, we can create new alloys that are non-eutectic, so, things that will not alloy together.”
Delivering mechanical performances involves four levels. First, the source material is from certified chemistry materials, i.e., from high end machine shops that supply parts for airframe manufacturers for example.
“One of the things we’ve been able to demonstrate is to take the oversized gas atomized powder that has almost no value on the marketplace because it doesn’t fit the powder size distribution for any printing process, and use it as a feedstock and reduce its size. We have the ability to get access to sources of materials that are already well-qualified as strong, certified chemistry.”
The 6K process is also contaminant free. The process is also qualified on the back end to look at any potential contamination, as is not always possible in a regular powder production facility.
In addition, the powders have superior properties over traditional atomized powders. They have better flowability, higher tap density, no satellites, and better scarcity.
“And one of the things that also distinguishes our powder, is there’s no porosity. Porosity is a natural outcome of an atomization process by virtue of the way they make the powders. And then, what we’re also finding in initial print studies is that the strength, both ultimate and tensile strengths, are superior to gas atomization. And we have some certain metallurgical advantages through the way that we actually produce our powders. We can engineer our feedstock to be any size, creating a targeted, or engineered, or “tuneable” size for powder. We can create powders within virtually any range.”
As with other materials and additive technology, 6K’s powders fit a number of industries, including oil and gas, aerospace, space, medical, and commercial.
“In medical, we are pioneering new types of alloys to use in orthopedic implants. Alloys that cannot otherwise be created in typical atomization processes,” continues Bent.
“This is where I think sustainability and cost are intimately linked. And I think with a better total circular economy approach to both the printing and powder production process, you can have substantial reduction in costs and therefore a faster adoption of AM.”
Raw materials are quite low in cost. Because the 6K process offers 100% yield rather than 30% yield, which contributes to a lower cost as well. Bent believes he can offer a more interesting value proposition to a typical customer if 6K can take the customers’ waste from their processes, and deliver back high-value powders; powders that perhaps they could not otherwise obtain, and create a symbiotic relationship and a true circular economy.
6K has upcycled a million pounds of titanium a year. Much of this material goes into grain refining elements for making aluminum. Thus, that million pounds of titanium upcycling enables a billion pounds of primary aluminum production.
“And that finds its way into things like medical ventilators, Ford F-150s aircraft and medical components as well, says Bent. “We have just commissioned our 40,000 square foot, state of the art production facility in Pittsburgh, where we will be launching both our Inconel 718 super-alloy powders as well as following up with our Ti64 powders.”
Ceramic materials turned into powders is also an available material.
“We have worked in a variety of ceramics over the years for other applications that range all the way from 50 nanometers up to a couple hundred micron. Garnets and thermal barrier coatings, YFC Illumina, a series of different materials. It’s relatively easy for us.”