Additive opportunities expand

A printed utility vehicle at IMTS 2016, built by CI in cooperation with Oak Ridge National Labs.

Additive manufacturing has drawn interest from all areas of manufacturing. While various types of additive manufacturing (AM) processes are in use or are being developed, many fabricating shops are wondering if or how it fits into their business.

On the whole, the technology in all its permutations is finding its most valuable applications in the shops of original equipment manufacturers. However, those applications are becoming more varied all the time. And some of this development is being done by machine tool, welding, and robotics suppliers all fabricators know well.

Big Area Evolution

Cincinnati Incorporated (CI) began changing the additive discussion in 2014 when, in cooperation with Oak Ridge National Laboratory, it launched its Big Area Additive Manufacturing (BAAM) technology.

BAAM takes the 3-D printing of plastic to a large scale.

“Oak Ridge had funding to pursue large-scale 3-D printing, but the challenge it had was the development of a delivery system for it,” said Matt Garbarino, director of marketing communications for CI. “At the same time, our business development team had been looking at options to diversify our business.”

The cooperative R&D agreement that the two entered into in 2014 continues today.

BAAM essentially equips the delivery system that CI uses for its laser cutting tables – the frame and the drive system – with an extruder that can run 80 to 100 lbs. out of the extruder head per hour. Granules of plastic material (mixed to include whatever other type of material you wish to use, such as carbon fiber) are sucked into a dryer. That material is then preheated and run to the extruder head, which heats it up and deposits it on the build bed.

In September 2014 at IMTS in Chicago, CI printed out the body and chassis of a prototype car for Local Motors. It used an ABS carbon fibre plastic and took 44 hours to print. The car was assembled on the show floor and driven off it that same week.

Demonstrations of this sort have continued at various shows: the printing of a Shelby Cobra at the Detroit Auto Show; a 3-D printed house; and a 3-D printed excavator.

This detail of the running board of the printed utility vehicle shows the layered appearance of the part when it comes out of the machine prior to finishing processes.

Garbarino said that the most exciting aspect of the BAAM project right now is materials development, because the materials change depending on the application in question.

“Is it going to be used in a marine environment where there’s salt water and UV light? That will change your mix of materials. For instance, ABS carbon fibre doesn’t perform well in salt water and UV light, so you would want to use something other than that in the application,” he explained. He went on to note that while you always have a thermoplastic base, any number of fibres, such as carbon fibre, fibreglass, wood particles, and bamboo, can be added for certain properties. Each performs differently, and any number of permutations are available.

He was also quick to point out that when you are extruding at 100 lbs. an hour, the finish on the product isn’t going to be perfect. “There will typically be secondary or tertiary operations; either you machine it down or put a filler on the material,” Garbarino said.

And building a product with BAAM isn’t like cutting on a laser in that you can’t just transfer a file to the machine and push a button to let it go.

“We really have to prequalify companies that are interested in using the system,” said Garbarino. “You may have to produce a part in sections based on its geometry, or the structure might be such that there are certain angles and curves that if you were to try to print it the way it was designed, [the structure] would drop in on itself, so you would have to add support structures to print it. Some of that is a matter of developing a knowledge base and defining rule sets, and that’s not mature yet.”

BAAM is in a place not unlike powder bed AM machines for metals were six years ago when that technology began to grow. Garbarino noted that some companies with BAAM machines now are working on material development, as is the CI / Oak Ridge partnership.

And the relationship between an AM technology supplier and its customer is much more a partnership than it would be if the customer were buying a laser or a press brake.

“Once we understand the application and how we can support the customer and what they need to take on themselves, we can work with that and help them develop their process, with the support of Oak Ridge,” said Garbarino. “In this way we all learn through the process. It’s a very different business model.”

As for applications, CI is seeing the biggest traction in aerospace, where the technology can be used to make moulds for fibreglass projects. Like using additive metal processing for small moulds, the lead time to make the mould is short, the cost is comparatively low, and if the mould isn’t correct the first time, it is relatively inexpensive to scrap it and rebuild it.

“The savings one particular company is seeing are pretty compelling, and they are running that BAAM machine all the time,” said Garbarino.

Parts in the BAAM machine. Image courtesy of CI.

But the application opportunities are broad. An OEM building an agricultural vehicle, for instance, might want to build parts or shells for the vehicle. So there may be various applications in transportation, to name but one industry. The use of BAAM could allow a company to eliminate certain stamped or plastic formed parts.

Another possible application that has been discussed is building moulds for windmill propellers on-site to avoid the transportation challenges involved in their production.

On the machine tool technology end of the BAAM development, CI is thinking carefully about its delivery system. “The drive system is faster than the process can deliver,” said Garbarino. “It is overkill for where the technology is right now. So is that the right drive system? We used it because we had it on our lasers and was quick to market. That’s one area in which we may be exploring some changes.”

The frame is another consideration. The machine has a laser frame, which limits the print envelope. CI now offers three different machine sizes, but Garbarino believes the process could still be opened up more for bigger applications.

Big Metal Melt

Wolf Robotics is a relatively new subsidiary of Lincoln Electric. As Project Manager Jason Flamm explained, the company’s newly developed large-scale metal additive manufacturing process takes advantage of the strengths of the subsidiary and its parent company.

“3-D printing is taking a deposition process and applying it to the end of a motion system,” said Flamm. “You use software tools to automatically generate path motion in the form of a shape or geometry. Lincoln Electric has been in the deposition business for more than 100 years. Wolf Robotics’ expertise is robotic automation systems and welding processes.”

Wolf has specialized, more particularly, in more complex custom systems integration and applications.

It was back in 2014 that Wolf Robotics was approached to start doing some robotic 3-D printing – an application for Lockheed Martin for polymer-based printing. Wolf used a robotic arm to deposit the material. After that project, the company went back to its roots to try the same process in metal.

At FABTECH® 2016 the company demonstrated an application using an arc welding process to deposit the metal wire.

The Wolf Robotics additive system mid-build. Image courtesy of Wolf Robotics.

“Most work we have done has been on the arc welding platform, but we do have an America Makes project right now that involves direct energy deposition using a laser application,” said Flamm. “Some materials are easier to deposit with a laser, such as titanium, but a laser is of course much more expensive. The arc welding system is more economical, whereas the laser has a slightly higher deposition rate.”

Flamm sees a great deal of opportunity for AM in low-volume spare parts production.

“It’s an alternative to some types of castings for which customers have a hard time finding foundries to do that work for them,” said Flamm. “It’s effective for prototypes or one-off parts for legacy equipment. It could also be useful for the tooling industry for projects where the long lead times of regular tooling don’t fit the short-run needs for certain applications.”

At ConExpo this year, Wolf Robotics printed a stick for an excavator that was 7 ft. tall and weighed about 400 lbs. It was actually installed on the machine and was moving dirt during the show. The stick required about five days of printing (not all of it on the show floor). A trenching bucket was also printed for display at the show.

As a metal additive process, this process is probably the least cost-prohibitive, with its own niche applications. At this point, Flamm noted, the company is still very much in the development stages in terms of understanding the most effective and economical applications for the technology.

Powdered Metal Innovations

Metal powder AM is performed in two different ways depending on your requirements: It can involve adding structures to an existing substructure, a process known as laser metal deposition; or it can involve building a full part from scratch in a small enclosure, which some refer to as laser metal fusion.

Laser metal deposition machine tools have been developed by the likes of DMG MORI and TRUMPF. DMG MORI’s system is a combination of a milling machine and an additive machine. TRUMPF’s system essentially started as a laser cladding machine in the late 1990s, but as Frank Geyer, additive manufacturing product manager at TRUMPF, noted, more and more now it’s getting used for structural buildup of parts. The company’s largest machine has a working envelope about the size of a car, but it also has created a system called the TruLaser Cell 3000 that allows you to cut, weld, and deposit metal on smaller parts.

Although, like many additive applications, structural buildup has been most enthusiastically adopted by the aerospace sector, Geyer considers that it has great potential for use in automotive part development as well.

“I think it’s interesting for when you want to create common parts,” said Geyer. “You might have a component that you can make common across several platforms in its base geometry. The base geometry is the same but you have certain vehicles that have higher load capabilities, and the base part can be added to according to needs. Typically right now a common part would match the highest load capacity required of all the vehicles. This changes that equation, and could be much more cost-effective.”

A sample part built in TRUMPF's AM machine. Image courtesy of TRUMPF.

The technology is also suitable for part repair and, of course, cladding.

Powder bed AM (laser metal fusion) – building a part from scratch in a small build space – has probably received the most media attention in the past few years because of its enthusiastic adoption by the likes of GE for aerospace production. It has also been adopted in medical and dental applications for its value in creating customized one-off structures, which are ideal for building implants or dental work.

SLM Solutions, under a different name, was one of the early developers of the technology in Europe. As Jim Fendrick, vice president of SLM Solutions North America, said, in many ways it’s now a very mature technology.

“Lasers for this application really haven’t changed since fibre optics were introduced,” said Fendrick. “You have limited scan fields with the lasers, which is why everyone developing systems is fixated on that 280- by 280-mm-square build environment. That is the scan area of the laser with the current designs, and your incident angles start getting too big on the outside edges; beyond that size you can’t control part quality. You also can’t increase the speed of the laser to increase your productivity. You can use a higher-powered laser for some materials like aluminum, which can take more power, but typically your steels and alloys can’t absorb energy fast enough to make a more powerful laser an effective means of increasing productivity.”

Because of the technology’s maturity in many ways, companies are having to be creative about differentiating themselves in the market.

SLM now has machines with multiple lasers to speed processing time and/or increase the part size a company is able to produce in one machine. Its SLM 280, a standard-sized bed, comes with either one or two lasers, depending on your production speed needs. Its SLM 500, which has a larger bed, comes standard with two lasers, or you can get two additional lasers.

The company has also improved the way weld fumes are evacuated from the chamber; according to Fendrick this can have a great effect on surface finish. He noted that the surface finish on parts from these machines is “typically similar to a high-quality investment casting. These are basically shop floor investment casting machines.”

The robustness of laser metal fusion machines is also a challenge. Every company in the industry is working toward making them more like machine tools in durability. That’s where TRUMPF feels like it has an edge. The company built its first laser metal fusion machine, called the TrumaForm, about 14 years ago but couldn’t find a large enough market for the technology. It re-entered the market in 2014 with Italian company SISMA in a joint venture and has since released the TruPrint 1000 (for jewelry and other very small components) and the TruPrint 3000.

“We approach our designs as a machine tool builder,” said Geyer, implying that the machines have to be efficient and productive. Two aspects of the company’s product design are particularly geared to speeding up processing: its supply cylinders and unloading process.

“Typically, if I want to build a complicated part, I have to oversupply powder to ensure that every time I put a layer on, I have all the voids and structures covered with an even layer,” said Geyer. “But to do that, I might need more powder than one cylinder can hold. With complicated builds it’s not uncommon for a machine to run out of powder mid-build. We have added a second cylinder to ensure that this doesn’t happen.

This turbine, 16-in. long by 20.5-in. wide, highlights several laser-based manufacturing applications: The main body has been built up on the TruPrint 3000 using laser metal deposition; on the body, several golden-coloured tracks have been deposited. The letters LMD and the TRUMPF logo were engraved through laser ablation. The wave-cut end of the turbine was laser cut, as were the wing structures. Image courtesy of TRUMPF.

“The majority of machines we see require you to unload the part off a plate in the machine,” Geyer continued. “But most standard-sized machines have a preheat temperature of 200 degrees C, which means you have to wait a couple of hours before you can even touch the part. In our machine we have what we call an external powder handling unit, so when a job is done, you seal the cylinder it’s in, put a lid on the cylinder, and take the entire cylinder out. It can be placed in an unpacking station to cool down, and meanwhile you can get another part into the machine.”

The TRUMPF system also allows you to vary the laser spot size on-the-fly, depending on the feature type being presented.

Powdered metal additive machines of this type will likely remain geared to small-run parts of all kinds in many shops, but some companies are dedicated to automating the production process and encouraging high-volume production. Aerospace, medical, dental, jewelry, tool and die moulds, and other complex components are the heart of this market. SLM’s Fendrick noted that some automotive firms have purchased machines from his company, but they are geared toward prototyping work.

You can expect to see more applications for AM among your clients and, if you are working for an OEM, on your shop floor. Each new AM development creates a broader reach for the technology.

Editor Robert Colman can be reached at rcolman@canadianfabweld.com.

Cincinnati Incorporated, 513-367-7100, www.e-ci.com

SLM Solutions, 248-243-5400, www.slm-solutions.us

TRUMPF Canada Inc., 905-363-3529, www.us.trumpf.com

SLM Solutions' dual-laser AM machine in action. Image courtesy of SLM Solutions.