Conestoga students demonstrate how new software allows for process refinement

Macor and McElhone used the Mastercam add-on APlus by CAMufacturing Solutions Inc. to develop their WAAM toolpaths, alongside off-line robotic programming tools (Octopuz) for a FANUC robot. A Lincoln Electric welding machine used in the tests employed the company’s STT process on an ER70S-6 welding wire. Images: Jackson Macor and Scott McElhone

Additive manufacturing sparked great interest when powder bed fusion systems hit the market around 10 years ago. The idea of “building” a part from the ground up rather than using extractive processes showed great promise for intricate aerospace assemblies and any other application where complexity made machining challenging. Ceramic Lined Valves

Conestoga students demonstrate how new software allows for process refinement

The cost of the powder bed technology, and its corresponding applications, made its adoption a niche proposition.

Wire-arc additive manufacturing (WAAM), in contrast, doesn’t have the same barrier to entry. Using welding machines to run the process and welding wire as feedstock, it is cost-effective and uses equipment most shop workers already understand well. The sophistication of robots and CAD/CAM software, however, has made the process more precise, opening greater application opportunities.

Jackson Macor and Scott McElhone, two recent graduates of Conestoga’s manufacturing engineering technology – welding and robotics program, demonstrated how precise the technology can be through the research they performed as part of their thesis work in their final year of school.

“Some of our faculty have been working on wire additive manufacturing research for a few years,” said Macor. “The opportunity came up to work with a company to produce thin-walled cubes. We started doing a project on just thin-walled WAAM when this opportunity came.”

Macor noted that although WAAM has been used for some time, much of its applications have been for thick-walled mechanical testing purposes.

“This gave us a chance to see how delicate a shape we could produce,” he continued. “We started with the cube but also a wide flange beam, a propeller, and other shapes. We wanted to observe what was possible playing with variable parameters. Having seen what has been created in plastic, we were sure many of the same forms could be reproduced using WAAM in metal.”

Macor and McElhone used the Mastercam add-on APlus by CAMufacturing Solutions Inc. to develop their WAAM toolpaths, alongside off-line robotic programming tools (Octopuz) for a FANUC robot. A Lincoln Electric welding system used in the tests employed the company’s Surface Tension Transfer (STT) process on an ER70S-6 welding wire. STT is a patented controlled short-circuit transfer GMAW process that uses Lincoln’s Waveform Control Technology.

“Using the Lincoln technology, it gives us increased control over the weld puddle,” said Macor. “The machine also knows to compensate when there’s a change in voltage or amperage.”

“Working with Mastercam’s software, we were trying to prove out their technology and build upon it,” said McElhone. “Building a cube is a useful test because it’s difficult to construct a part using WAAM without moving it because you are fighting gravity. We were able to do so in four months of research.”

Conestoga students Jackson Macor and Scott McElhone demonstrated how precise WAAM technology can be through research they performed as part of their thesis work during their final year of school. A precise cube was the ultimate proof of their capabilities.

The goal of the research was to be able to leave the setup unattended overnight and for the team to return to the office to a perfectly completed cube without having to manipulate the part in any way during that time.

“In a way, it’s simplifying the technology,” said Macor. “Having to manipulate a part complicates setup and makes the production of larger parts problematic. With our toolpath set, that is no longer an issue. You could build a much larger cube using our toolpath designs, and it should run the same way.”

The secret to the print was partially determining the correct angle at which to approach it.

“Initially we tried to start welding directly on the corner, but robot movement around that was an issue,” said Macor. “We had to adjust the robot speeds around corners because in some situations it was going too fast through the corners, causing issues with the finish.”

Ultimately, the robotic programming was the most challenging element of the project for the pair.

“Other concerns like the angle of the torch head and travel speed had to be worked out through trial and error to get the right thickness and proper delivery, but the software was the biggest challenge because we weren’t as experienced with it,” said McElhone. “What might take us 20 minutes to program now required about 10 hours of development in the early stages of the project.”

Eventually, the two were able to produce the cube with a wall thickness of just 3 mm.

“What’s nice about weld beads that thin is that it provides a nice surface finish,” said McElhone. “In one of our completed samples, the finish was basically smooth to the touch.”

They also observed interesting changes in the material properties as the cube was built.

“What we found is, even though we're using a regular wire, you're getting grain refinement,” said Macor. “Grain refinement is huge in the welding industry. An ER70S-6 welding wire has 70 KSI of tensile strength. The ductility is around 12 to 15 per cent. When you print, as you're going layer by layer, at layer 20, layer 15 is actually being heated up rapidly and then cooled rapidly, causing a tempering effect. With a 70-KSI wire, now we're getting between 25 and 30 per cent ductility, which is ridiculous.”

The production of a hollow, wide flange beam suggests the possibility of creating structural parts that can carry tremendous amounts of weight using less material.

Macor and McElhone estimate the key applications for WAAM will be in castings and forgings, which take a long time to produce and are affected by poor material properties.

“With WAAM, we can produce a similar product to castings with high ductility and way better properties with a much faster turnaround time,” said McElhone. “Realistically a company could print on-site, not having to rely on shipped castings.”

The production of a hollow, wide flange beam suggests the possibility of creating structural parts that can carry tremendous amounts of weight using less material.

“With a portable printing setup, it would also be possible to build such products on-site in areas where people can’t enter—for instance a nuclear facility,” noted Macor.

“The key outcome, though, is that we’ve shown that you can produce parts using this technology without constantly watching its progress,” said McElhone. “In the past, companies using WAAM would watch the process and simply grind out errors as they happened. Newer technology allows you to produce without that wasted processing time.”

Although Macor and McElhone were impressed by what they were able to create with the use of robots, they feel that truly precise work using WAAM ideally would use some type of gantry-style build structure.

“As precise as robots can get, it can’t compare to what is possible in a setup similar to a mill or lathe,” said Macor. “We can produce parts with 3-mm walls. The precision of a gantry-style setup would help refine the look of such a part.”

But that is a comparatively minor point. Ultimately, this research shows that even delicate structures now can be programmed and created with the right tools.

“It’s a cost-effective technology compared to other additive manufacturing methods,” said McElhone. “The turnaround times are fast and the properties of the material excellent, and you can basically do it at home or anywhere out in the field.”

Editor Robert Colman can be reached at [email protected] .

Toronto, M1R 0A1 Canada

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Robert Colman has worked as a writer and editor for more than 25 years, covering the needs of a variety of trades. He has been dedicated to the metalworking industry for the past 13 years, serving as editor for Metalworking Production & Purchasing (MP&P) and, since January 2016, the editor of Canadian Fabricating & Welding. He graduated with a B.A. degree from McGill University and a Master’s degree from UBC.