Case Study: Robotics Integrator Discovers Binder Jet 3D Printing for Automotive End of Arm Tooling

Case Study: Robotics Integrator Discovers Binder Jet 3D Printing for Automotive End of Arm Tooling
Case Study: Robotics Integrator Discovers Binder Jet 3D Printing for Automotive End of Arm Tooling

Metal 3D printing provided weight and cost savings over machined alternatives for a FANUC robotics systems integrator in need of an end-of-arm tooling (EOAT) solution.
 
Allegheny Electric Service—a control systems design and industrial automation provider for the powder metal, lumber, and metal stamping industries—was asked to create durable and lightweight EOAT for an automotive manufacturer’s robotic inspection process. A six-axis FANUC robot needed to pick up and place six different parts, of varying weights up to 2.5 pounds, for serial inspection running nonstop across three shifts. The number of parts being inspected in this factory environment ranges from 50,000 annually for the lowest-volume piece to 500,000 parts annually for the highest volume. A 3D printed piece was part of an assembly that needed to attach to two other EOAT pieces that needed, in turn, to sit 90 degrees to one another for a variety of different inspection techniques.

Oftentimes, an EOAT solution developed by Allegheny Electric would be 3D printed in plastic or carbon-fiber-reinforced plastic, or it would be machined in a strong, lightweight material such as aluminum, said Jake Shannon, design engineer at Allegheny Electric.
 
Although an initial prototype was originally 3D printed in a carbon-reinforced plastic, the weight requirements and processing volumes for the project eliminated this material from consideration due to a lack of durability: The rigidity and strength just weren’t there for the biggest parts. Additionally, machining the desired functionality, even in lightweight aluminum, would have produced an EOAT part that would have been at the upper edge of weight for the FANUC robot arm being used. This was also not considered desirable.

FreeFORM 3D printed the part in 17-4PH stainless steel. A 3D printed carbon fiber reinforced prototype, shown in black, was not rugged enough for use in the final application.


The technology partners

Allegheny Electric wanted to explore whether metal 3D printing could offer weight and cost savings through new design options, so they approached FreeFORM Technologies about both laser powder bed fusion—specifically, direct metal laser sintering, or DMLS—and binder jet 3D printing.
 
FreeFORM is a first-of-its-kind metal binder jet 3D printing contract manufacturer founded in 2020 by a group of engineers who bring a diverse outlook to metals manufacturing and a desire to be the benchmark for additive manufacturing. FreeFORM uses technology from ExOne, a pioneer in binder jet 3D printing technology. Since 1995, ExOne’s 3D printing systems have been quickly transforming powdered materials—including metals, ceramics, composites and sand—into precision parts, metal casting molds and cores, and innovative tooling solutions.
 
Using generative software from Solid Edge, computer-aided design and analysis software from Siemens, Allegheny Electric and FreeFORM collaborated on a new, lightweight design for the project that could only be produced with 3D printing. The design was quoted for both DMLS and binder jetting. In binder jet 3D printing, the printer uses a digital file to quickly inkjet a binder into a thin layer of powder particles—metal, sand or ceramic—creating a solid part one layer at a time. When printing metals with DMLS technology, the final part must be sintered in order to fuse the particles together into a solid object.
 

Using 50 micron layers of standard MIM powders, the ExOne Innovent+ metal 3D printer took less than a day to produce the final EOAT part.


Benefits of binder jetting

FreeFORM estimated that the part would cost $672 to create using DMLS, prior to any final finishing, and only $150 to create using the ExOne Innovent+ binder jet printer owned by FreeFORM. Chris Aiello, VP of Business Development at FreeFORM, says that because binder jetting is so much faster than other metal 3D printing methods, including DMLS laser powder bed fusion, it offers much lower costs that are more competitive with traditional manufacturing processes. Binder jetting also provides other benefits:

  • a sustainable method of manufacturing that reduces material waste to less than 5%,

  • energy savings from consolidating many assembled parts and processes into one, and

  • end-use designs that are 30% to 40% lighter.

Aiello said that the unique lightweight design generated in this case could not have been produced without of a 3D printing technology. FreeFORM was able to print a traditional stainless steel MIM powder, 17-4PH, with a D90 of 22 μm. This material was desirable because of its durability and corrosion-resistance—an important feature for a part that would be used in a factory with frequent temperature fluctuations, he added.

Printed on an entry-level Innovent+ printer, the final part exceeded MPIF standard 35, delivering a hardness of HRC 27 and a final density of 98%. Because that hardness met the customer’s requirements, additional heat treatment wasn’t required.
 
“They could have gone with a simpler design in aluminum, but the part would have actually been heavier to get the same strength as 17-4PH,” Aiello explained. “By going with this kind of organic generative design, they were also able to reduce the overall payload on the machine, so it’s likely going to extend the life of the robot for the customer.”

In this case, FreeFORM decided to machine three critical features on the part to further dial in accuracy. These included a few holes and one surface for final flatness. Binder jetted parts take to machining just like standard metal materials, said Aiello: “It’s very similar to machining wrought material, and it looks no different than a machined metal flat stock part.”

The part as designed had a build volume of 160 x 65 x 65 mm (6.3 x 2.5 x 2.5 in) and a weight of 95 grams. The initial printing of the part, using 50 micron layers of standard MIM powders, took less than a day of printing on the Innovent+, a printer that has been on the market since 2016.
 
The Innovent+ was not only fast; it also delivered reliable parts. “The surface quality is superior to any of the other printers,” Aiello said. “It’s an easy machine to run. It was great for this kind of application.... The Innovent+ is definitely meeting plus or minus 2.5% to 3% accuracy (for first runs), which is the kind of out-of-the-box performance that the engineering team expects.” The Innovent+ can dial in even better accuracy (below 1%) with 2 to 3 iterations.

The complex part designed in Solid Edge and 3D printed with binder jetting technology enables two tools to sit on the end of a robot arm at a 90-degree angle to each other. They must hold a variety of weights for a high-volume precision inspection application.

 

The future

While this project didn’t have a high-volume part requirement for the final EOAT—only four parts were initially needed—Allegheny Electric Service was eager to do the project to explore whether binder jet 3D printing was ready to produce affordable parts in unique designs that could deliver higher performance in its automation applications. Now, it has a new solution option to offer customers that can deliver durable, lightweight parts in metal at affordable prices.

“We are always working within the design constraints of traditional manufacturing,” said Shannon. “Now we can focus on design intent and process optimization to meet or exceed our customers’ expectations. We will definitely continue to offer our customers end of arm tooling produced with binder jet 3D printing. An important feature for us to offer our customers is how this technology reduced the payload on the robot.”

For Aiello and the FreeFORM team, this project showed the new design possibilities they can now offer in standard and durable metal materials at affordable prices. The FreeFORM team has deep experience in powder metallurgy and MIM, and they say the parts they are now producing with binder jet 3D printing are equivalent to the type of product they were producing with those traditional processes. However, now they can deliver those parts without tooling and with more geometric freedom than ever before.

“This project shows exactly why we started the company—to help customers solve challenging problems,” Aiello said. “Binder jetting was really the only way to go for this project. It was one-fourth the cost of DMLS, and we did it in a strong material that reduced the payload on the robot. As Allegheny Electric Service rolls this technology out, it’s going to be a bigger savings for their customers.”

About The Author


Sarah A. Webster is chief marketing officer at The ExOne Company.


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