Big Metal Additive: The Difference Between a Shape and a Part Is Quality

Metal additive manufacturing can, in some cases, take the place of casting. Or can it?

Slade Gardner says the key to appreciating all that this question asks is understanding the foundry’s role, and how meaningful that role is. He is the founder of Big Metal Additive in Denver, Colorado, a specialist in directed energy deposition (DED) that is, indeed, increasingly being asked to deliver AM parts that stand in the place of castings. “People see the shapes 3D printing can produce, and they get confused — they think the shape is enough,” he says. Yet a foundry is doing something deeper than making a shape; it is making a part. This means AM filling in for the foundry’s role has to make parts as well.

This difference is in defined and specified requirements, he says. The difference is carried out not through 3D printing but through systems and procedures, and the organization applying them.

The difference between shapes and parts is a gap that can only be bridged by a quality department.

Gardner has been leading Big Metal Additive through this very transition: from shapes to parts. The company applies wire-arc DED using its own in-house-developed deposition technology on both robot systems and five-axis hybrid machine tools. DED can deliver “impossible shapes and impossible schedules,” he says — and in recent times, it has been the latter of those two impossibilities that has driven business. Various increasingly pressing U.S. Department of Defense needs meet with hurdles related to casting lead time and foundry availability. Submarine components made from copper-nickel alloy offer one example, and an extreme version of the problem.

“No foundry wants to cast six per year of an exotic alloy part,” Gardner says. But with additive, and with his company’s DED processes, he says, “We love six per year. Give us that quantity times 20 different part numbers. We can switch between them as needed and produce every part on demand.” A foundry cannot operate this way.

Part buyers with the DOD, among others, recognize the value of this possibility. Several different fully developed projects seem likely to transition into ongoing production jobs, any one of which will require Big Metal Additive to scale. In multiple cases, the only remaining uncertainty hinges on when and to what extent federal funding will be allocated to the work.

In the meantime, says Gardner, the company is preparing to scale, and is ready. He has identified sources for additional machines that his company will turn into additive equipment. But this is just the hardware. Another element is equally valuable: The company has also developed a training program for new hires focused on its production system, and the heart of that production system is a quality department now comprised of four out of the company’s current 25 employees.

Establishing this quality department is easily the most important major step the company has taken in recent years to prepare for its coming role in ongoing scale production, and the existence of this group is what separates Big Metal Additive from many other metal part producers using AM. It is what gets the company from making shapes to making parts, Gardner says. This is a particularly meaningful victory, he notes, because it was not that long ago that just making shapes was the accomplishment that had to be mastered.

Toward the Factory of 100 DED Machines

When Big Metal Additive began in 2016, Gardner was its sole employee. He came from the space division of Lockheed Martin, where he had been involved with AM to create propulsion tanks. He founded his company because he saw promise in refining and advancing DED as a production process. The first machine the company developed for itself was a five-axis additive machine tool that could not actually deposit material in five-axis paths — because no software for the machine yet existed. The company worked with Siemens to create this: programming capability for five-axis deposition and machining tailored to Big Metal Additive’s system. In some ways, he says, the company really began with the arrival of this software.

What followed was years of developing knowledge related to the best tool paths, extra stock for machining and where to place it, when and where to machine during an additive build, and how to control against chatter in building and machining complex structures. Much of this learning was funded, because it was performed as part of Small Business Innovation Research (SBIR) grants related to DOD projects — such as the work done to help the Air Force understand the possibilities of topology-optimized aircraft structures. The result: Big Metal Additive now benefits from a proprietary platform and proprietary techniques on that platform related to not just DED but five-axis DED coupled with in-situ machining.

The company has six machines today, three robots and three machine tools. Its biggest and newest machine is a gantry machine tool with 12 feet of travel in X and Y and 8 feet of Z travel, so big relative to the facility that a pit had to be dug to fit it beneath the ceiling.

But Gardner says the most significant area of scaling will not be in the size of machines but in the number of them.

“Our strategy is, we will have a factory of 100 machines,” he says. “They will run a diversity of applications. We will have four to five major customers we can serve by diving deep and really knowing their needs.”

The first step: The company is watching for the first customer whose production demand will require a line of 10 or so machines to satisfy the need. It is not an idle wait; several opportunities are drawing close. The closest, says Gardner, probably relates to submarine hardware. Here, additive manufacturing will take the place of casting for copper-nickel, an alloy for which foundry capacity is even more limited than foundry capacity in general.

Or, another looming opportunity relates to 5-inch artillery rounds for the Navy, which today are made through forging not casting, but the lead time impediments are the same. With this part — the steel body of the projectile — 3D printing and machining can be completed in well under one shift, allowing for multiple rounds per day. Indeed, this part by itself could easily justify a 100-machine factory. One hundred DED robots and 100 lathes would enable Big Metal Additive to feed the Navy 600 projectile bodies per day, he says. And a factory like this could shift from producing 5-inch rounds to producing other artillery sizes, making the change on a moment’s notice.

DED is capable for this kind of production. The company’s DED platform, on its own, does not need to be changed to realize this. But systems around this capability have needed to advance.

“We have not been trying to elevate TRL,” he says, meaning technology readiness level. “We have tried to elevate manufacturing readiness level, MRL. Everyone is fascinated with getting to TRL 7 [pilot system]. No one is thinking about MRL 6 [running in a production environment].”

It was that pursuit of manufacturing readiness that ultimately led to the point where DED technology and technique were no longer the focus, but instead the focus had to be on the system that could translate this capability into parts routinely acceptable to a customer.

A Part Has a Drawing That Calls Out a Spec

“Until we implemented a quality system, we felt like a prototype shop,” Gardner says. In short, making shapes, not making parts. “The quality system is what lets us know we are a manufacturer.”

Leading much of that implementation has been company employee Andrea Barnes, a metallurgist who came to the company from the casting industry, who asked for the opportunity to spearhead quality efforts, and who is now director of quality. For Big Metal Additive, that term, “quality,” refers to adherence to various sets of requirements. The company’s system is now certified to AS9100, and also compliant with “a long list of additive manufacturing standards for customer part acceptance,” Gardner says.

But the experience of this in practice — the day-to-day difference between the feel of prototyping and the feel of production — comes down to something basic. “Everyone has to follow the paperwork now; everyone fills out the paperwork,” Gardner says.

In fact, in a sense, paper — or its digital equivalent — gets to the difference between a shape and a part. “It is not a part unless it has a part number, which references a drawing, which calls out a spec,” he says.

And this gets to the point that is obvious to any quality manager, but hard to appreciate when viewing manufacturing from a distance: The role of quality exists because a production part of any significance or value has so much definition and specificity to its requirements that just capturing and confirming adherence to all the requirements is a vital part of the work.

“Procedurally, we started creating processes to follow, including folders of process forms and documents to define each job with uniformity and clarity,” he says. Describing a path other manufacturers have walked, he says, “We now know how to purchase and receive things [like raw material] to give us traceability. We know how to extract performance requirements from customer contracts.”

DED helps. Big Metal Additive’s process is based on gas metal arc welding. Standards for this already exist, which can often be adapted to additive. Welding or AM standards from ASME, AWS and NASA, plus customer-specific requirements, figure into the compliance needs of much of the company’s work. The system assuring this compliance as part of routine operation provides perhaps the most important plank in the platform that will enable the company to scale.

It still does not come easy. “When we do bids today, we are about 2:1 in the ratio of engineering hours to quality hours,” Gardner says. He thought that seemed like a lot of quality hours. But then he spoke about this to a career manufacturing leader with a major industrial OEM. He says, “I learned the ratio they expect is more like 1:1.”