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Metal AM Adoption Racing Ahead Of Capacity To Provide Qualified Workforce

Metal additive manufacturing has been in use long enough for users to have figured out best practices related to safety and part inspection, but challenges remain in terms of workforce, controllers and automation, and plant and process certification.
 
“At the rate of adoption in industry now, we’ve outstripped the capacity to provide a qualified workforce,” Tackett said.An aerospace swirler made with an EOS metal AM machine.

Jim Fendrick, vice president, North America, at SLM Solutions (Novi, MI), said: “One of the first things I get asked when I visit a vendor is do you know of any good technicians?”

The problem is widespread in manufacturing in general, as millennials and others that will make up the future workforce view manufacturing as old school, something their parents and grandparents made a living at. Training a qualified workforce will likely require collaboration between industry and academia, not to mention convincing the younger generations that manufacturing jobs are worth aspiring to.

Tackett’s UL colleague, Chris Krampitz, director of strategy and innovation for digital manufacturing technologies (Chicago, IL), agrees that assembling a workforce is a big challenge—and puts numbers to the problem: “When we look at the workforce that’s required for additive, we’re facing a large shortage. By 2025, we’ll see a worker shortage of 2 million across manufacturing (in the United States), and it’s even more difficult with additive because of specialization.”

There are at least two major problems with finding qualified workers for metal AM: skillset and the pool of potential workers.

Tackett noted it takes a very broad set of skills to work effectively in a metal AM operation. Workers need knowledge of and skills in computer science, metallurgy, coordinate measuring systems, mechanics, gas flow, heat and lasers, for starters.

“The list goes on and on,” he said.

Design is another skill that’s lacking in today’s metal AM operators, Krampitz added.

“In traditional manufacturing, you designed a part for injection molding; nowadays if you’re running a plastics additive machine and you design a part as you did for injection molding, you have no competitive edge,” Tackett said. “Now I can design purely for function.”

“Skillsets aside, there’s no pool of people to pull from,” he said. “When CNC machining came around, at least you had a pool of experienced machinists to pull from.”

Optimization on the Shop Floor

Also challenging is automating production to get the most out of a shop’s investment in machinery, and integrating metal AM into production work.

Andy Snow, senior vice president of development for EOS North America (Novi, MI), said one of the biggest challenges the metal AM industry as a whole faces is automation. His company’s solution has been to partner with other companies already expert in automation with the use of robotics, palletized chucks and other technology. A palletized chuck is a workpiece holder that transfers from one machine to another while maintaining critical reference points. By doing so, it ensures accuracy and increases efficiency.A look inside the build chamber of the SLM500, equipped with four lasers to make complete engines.

In June 2015, EOS partnered with GF Machining Solutions (Schaffhausen, Switzerland) to develop solutions for moldmakers. EOS’ machines are well suited for making metal inserts with cooling close to the surface, speeding up mold cooling and hastening the plastic injection cycle. GF will contribute software and link the EOS machines downstream with its EDM and high-speed milling tools, and measuring devices.

Other types of software are also needed.

When additive machines were used strictly for making quick prototypes, their manufacturers gave little thought to equipping them with the technology that would make it possible to connect them to each other, to other production machines, or to the Industrial Internet. Now that AM machines are moving to the factory floor, manufacturers will have to play catch up.

“One of the big things right now that is very desirable is to have process controls,” Krampitz said. “If something goes wrong, there’s nothing to bring it back. We need control loops so the machine can sense what’s going on with the part build and take corrective actions if necessary.”

Organizations like America Makes (Youngstown, OH) and companies such as 3DSIM (Park City, UT) are working on software for a logic controller for AM machines, Krampitz said.

Experts at the University of Louisville are also working on algorithms that would tell an operator there’s a problem, Tackett said.

“It’ll be six to eight months before we see that transition to machine manufacturers,” he said.

Tackett said the lack of feedback built into the machines makes them incapable of interfacing with the Internet of Things.

“We’re only right now at the phase of getting these machines smart enough to correct errors,” Tackett said.

In fact, SLM made its automated layer control system, formerly an add-on, into a standard feature on all of its models in 2015.

During a build, the machine takes a picture to detect and correct powder preparation and execution after each cycle. If it detects a problem such as a short feed, where the powder doesn’t spread over the entire build area, the machine takes corrective action. If it can’t correct the problem, if the machine is out of material, for example, the machine notifies the operator via text message.

“I’ve done it myself over the weekend,” said Fendrick, who’s made the 10-minute drive from his home to work to correct a problem detected by the automatic layer control system.

Melt pool monitoring is another quality feature SLM was testing in March, as this first issue of Smart Manufacturing went to press. With this feature, the machine will monitor and record the properties of the pool of molten metal at the powder bed. This information can be evaluated to look for variances that might affect the quality of the part. The next stage of development will be to use the information collected to actually control the process, Fendrick said.

Certification × 2

Operating a facility certified in metal production, and having certified processes with demonstrated repeatability in making parts for OEMs and regulators like the Federal Aviation Administration and Food and Drug Administration, can both borrow from precedents set with subtractive manufacturing. This model turbine assembly for GE was made with an SLM metal AM machine.

Tapping into an infrastructure of advisors knowledgeable about metal AM part certification and ISO approval for a metal AM shop is still tricky, though.

“A major challenge, the largest challenge, in the adoption of the technology is in certification,” said Krampitz. “The infrastructure of support and advice to do health, safety and environmental reviews, among others, is very, very young and not known by industry. But we’re seeing third parties emerging, like us, to fill those gaps.”

He advises getting help from: America Makes (Youngstown, OH), a public-private partnership that’s working to innovate and accelerate AM, with a focus on startups and small and medium shops; the Additive Manufacturers Users Group (Chatsworth, CA), which hosts an annual five-day conference; and SME, which hosts the annual RAPID conference.

UL also has information on its web site.

EOS’ Snow said his company provides continuous training to clients to help them get the most out of their machines. He advises users to work with their OEM to understand the technology better and learn how to optimize it.

One challenge for working with metal AM is establishing a process that yields the desired results of accuracy, surface finish, and material properties, and is repeatable, Fendrick said.

“This is not accomplished just through tuning the build parameters of the machine to the specific geometry, but also assuring all outside influences are controlled during the process,” he said. “Companies have successfully designed an entire process that has accomplished this, but it is a challenge.”

In other words, the challenge is to design an entire process that will produce 10,000 parts that are exactly alike.

“The machine parameters must be accessible to the customer to adjust the process to a specific geometry,” Fendrick said. “But there are many other outside influences that also must be considered in the design of the entire process.”

“As these manufacturing companies adopt AM and bring it in house, actually having a facility that’s certified to do additive is important,” said Ed Tackett, “The problem you have is that people have a lot of expectations about additive and if they don’t do it right then it tarnishes the whole AM for that company forever. It’s just frustrating in an emerging industry to see that happen.”An automotive heat exchanger made with an EOS metal AM machine.

While there may not be a plug-and-play infrastructure of resources to help, there are enough to at least start a conversation before going down that road, Tackett said.

He cautions there’s some urgency in becoming schooled in metal AM.

“The time to go into metal AM is now, before we lose the competitive advantage,” he said.
  

Metal Hazards

Experts recommend wearing heavy-duty personal protection equipment to keep operators safe from inhaling powdered metal or letting it get into eyes or cuts in the skin. They also advise monitoring oxygen levels around AM machines that are in a tight or enclosed space, to guard against accidental poisoning from the inert gases that can seep out of the machines.

Fire set off by a statically charged spark interacting with the powder is another risk that can be mitigated by wearing a fireproof lab coat, having a Class D fire extinguisher that can put out metal fires, and properly disposing of the machine’s filters.

Learning Every Day

Industrial CT scanning for inspection offers a look at parts that’s unparalleled, and related software shows whether a part veers from its CAD drawing.

“There are a lot of people who’ve never even heard of this technology, but it’s the only way in the world to see internal or full volumetric defects,” Ben Connors, manager of inspection services at North Star Imaging (Rogers, MN), said of his company’s industrial CT scanners. “There’s no other technology that can do what it does, and it’s advancing quickly all the time.”

North Star does inspection on thousands of parts every year for aerospace, automotive, medical and defense manufacturers.

Inspection with an industrial CT scanner can take from seconds up to a few hours, but it’s much faster compared with other methods. That’s because the inspector doesn’t have to cut up the part.

Cutting up the part can introduce other problems.Personal protective equipment (PPE), such as this powered air-purifying respirator Ed Tackett, directer of education programs at the UL Additive Manufacturing Competency Center at the University of Lo

“With some of the other methods, there’s a risk of changing the part when you cut it,” Connors explains. “And then some of the measurements can be brought into question.”

Also, the CT scan process is unaffected by defects in the part.

“You can see through the entire part volume and not be inhibited by defects,” he said. “Some other technologies can be inhibited or slowed down by certain defects.”

Some of the defects a CT scan can reveal include: voids; lamination; heat-related defects (specifically, contamination in the powder or issues with the laser); weld-related defects (lack of fusion of one layer to another); and powder that wasn’t melted, is misshapen or doesn’t build out completely.

CT offers yet another advantage: a variety of software on the market can compare the part’s CT scan to its CAD model.

“The cool thing about CT scanning is that you’re comparing the inside and the outside of that model,” Connors said.

CT scanning combined with AM also affects the feedback loop that leads to refinements in design and/or engineering. The CT scan’s picture into the inside of a part is also a powerful way to convey information to engineers and designers.

“When you combine 3D printing with scanning it makes that loop so much faster,” Connors said.

While North Star and Connors have lots of experience inspecting metal AM parts, he doesn’t have an answer on whether any one of the different methods of metal printing (powder with nozzle; extruded wire or powder bed) is associated with any particular quality problems in the parts produced.

“The different methods all have some degree of issue with bonding/lack of fusion/voiding from one layer to the next,” Connors said. “What is not clear at this point is the difference in defects from one process to another, but they all have some type of defect or anomaly.

“It’s still a new area and we are learning every day.”


Published Date : 4/15/2016

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