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Binder-jet 3D printer use is on the rise

Binder jetting allows additive manufacturers to 3D-print larger volumes of parts

3d printing

The binder-jet process yields fully dense metal components that reportedly are accurate to ± 1% on overall dimension and have a surface roughness of 6 μm Ra or better. Azoth

When 3D printing first went commercial some three decades ago, even its inventors labeled it a rapid prototyping technology. More recently, pundits have begun referring to additive manufacturing as a low-volume, end-use part solution, largely due to its increased speed and relatively newfound ability to print metal, composites, and engineering-grade polymers.

And although 3D printing still can’t deliver six-figure, automotive-level production quantities, it’s definitely finding greater use among component suppliers.

Belief in Binder

One such supplier is Azoth, Ann Arbor, Mich. The vertically integrated additive manufacturer recently began producing 3D-printed medallions for the manual shifter knob of the 2022 Cadillac V-Series Blackwing, one of several 3D-printed parts on the vehicle.

According to a statement the automaker released late last year, “By leveraging additive manufacturing, the Cadillac team was also able to reduce costs and increase efficiency when developing the high-performance sedan’s manual transmission.”

The technology used to make the medallions is Azoth’s binder-jet 3D printer from Sweden-based Digital Metal. “We believe in binder jetting,” said Azoth’s co-founder and general manager, Cody Cochran, who had been operating competing AM systems when the company took ownership of its Digital Metal machine in 2018.

“I think binder jetting will be a very disruptive technology with manufacturers striving for higher part volumes,” said Cochran.

Binder jetting works by depositing a liquid polymer-based binder in precise patterns atop a bed of metal powder, coaxing the individual particles to stick together like wet sand. The process repeats layer by layer until the print job is complete, at which time the entire build box and its payload of parts is placed in a curing oven.

Next, the powder is removed—a manual process not surprisingly named depowdering—and the “green” parts are sintered in an atmospherically controlled, high-temperature furnace. The result is fully dense metal components that reportedly are accurate to ±1% of the overall dimension and have a surface roughness of 6 μm Ra or better.

Take One Make One

Cochran said that production runs of 20,000 pieces are probably at the upper end of what’s practical with binder jetting, although he expects the number to grow in the future. For anything higher than that, it makes more sense to switch to metal injection molding. (MIM is a mature process that uses the same powders as binder jetting but requires a significant tooling investment.)

At the other end of the spectrum are part orders of 10 to a few hundred or even a thousand—quantities that an increasing number of 3D printing providers are becoming familiar with, particularly those with binder-jet capabilities.

metal 3D printing

Binder jetting is a two-step process in which components are printed, then densified. A liquid polymer-based binder is deposited in precise patterns atop a bed of metal powder, coaxing the individual particles to stick together like wet sand. The process repeats layer by layer until the part is built. Then the build box and its payload are placed in a curing oven. Next, the powder is removed and the green parts are sintered in an atmospherically controlled, high-temperature furnace. Azoth

It’s the smaller quantities that perhaps inspired the moniker for Azoth’s Take One Make One methodology, yet Cochran is quick to point out that TOMO is a Lean inventory-management offering that is independent of quantity.

“When comparing all the different metal additive technologies available when launching this offering, we knew that binder jet was the only one that would provide both the quality and cost per part that people were looking for, regardless of order quantity,” he said. “That’s what we based our business model on, and we’ve been quite successful as a result.”

Filling Voids

Another company enjoying success with binder jetting is FreeFORM Technologies, St. Mary, Pa., where co-founder and vice president of business development Chris Aiello thinks it could be the next great AM technology.

“Binder jet is here,” he said. “It’s arrived. It’s a high-volume process, a low-volume process, and everything in between. It fills a lot of voids for manufacturers, no matter what they produce.”

When asked what “high volume” means to him, Aiello mentioned one customer that orders 4,000 pieces per month, adding that FreeFORM could produce far more parts if requested.

Like Cochran, Aiello sees binder jet as the manufacturing method of choice until quantities reach the tens of thousands, at which point they enter MIM territory. Even then, however, “there are a lot of small companies out there doing these volumes that don’t have the cash to spend on tooling.”

Aiello also mentioned the need to depowder parts. “That’s about the only downside to binder jet,” he said. “Removing the parts from the cake post-curing represents a big chunk of the labor cost, particularly on intricate parts or where there are a lot of internal features. Here, you need to hit them with a small brush or air nozzle to get all the powder out. Making matters worse is the fact that binder-jet parts are still pretty fragile at this stage. They’re about the consistency of chalk, so you have to be careful not to break them.”

Sintering adds cost as well. Even a small production furnace can run $700,000 or more, Aiello said, a pill that many researchers and design firms can’t swallow. This is why FreeFORM and others have begun offering sintering services in addition to 3D printing. “I don’t have exact figures, but from talking to our customers, I would guess that 50% of binder-jet owners don’t have a furnace.”

“Job One”

Harold Sears, technical leader for AM technologies at Ford Motor Co., agrees with these assessments. “With most additive technologies, the bottleneck is the machine,” he said. “That’s not the case with binder jet, where postprocessing remains the biggest constraint. Still, it’s an important technology. It’s scalable to production volumes, the process itself is quite flexible, and the part quality is good. Despite all this, it’s clearly not the only path forward.”

Sears stressed that Ford is technology-agnostic and has invested in a range of AM systems across its many locations. Ford boasts a variety of maker spaces and “internal service bureaus,” as well as R&D centers.

additive manufacturing

Shown is a medallion Azoth 3D-printed for the manual shifter knob of the 2022 Cadillac V-Series Blackwing. Azoth

Sears works out of the Advanced Manufacturing Center in Redford, Mich., one of five such Ford facilities worldwide. It’s his job and the job of others like him to answer the question, “How do we apply additive technologies to make today’s production processes more efficient, more cost-effective, and more ergonomically friendly for operators?”

“The second leg of that journey is scaling these technologies, when appropriate, to production,” Sears said. “In many cases, that means taking what were originally prototyping and small-batch processes and flipping them to automotive volumes.”

Production volume or not, Ford faces many of the same challenges as those in the aerospace, medical, and general manufacturing industry. Chief among them is the need to rethink part designs.

For instance, converting a 20-piece assembly into a single, multifunctional 3D-printed component is no small task, but it’s exactly these types of engineering feats that promise the greatest returns for any manufacturer. The same can be said for MRO and service parts—in many cases, these must remain available for decades. Here again, AM promises to reduce or eliminate tooling costs while greatly simplifying the supply chain.

“My responsibility at Ford is to accelerate the integration of additive into the traditional manufacturing space,” Sears said. “Binder jet certainly plays a role in this, but, as I said, it’s just one technology among many. Each has its strengths and weaknesses, and all are being evaluated to understand how they can help us improve product quality and overall efficiency. For me, that’s job one.”

About the Author

Kip Hanson

Kip Hanson is a freelance writer with more than 35 years working in and writing about manufacturing. He lives in Tucson, Ariz.