3D PRINTING
In fact, SLM made its automated layer control system, for- merly 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 ma- chine 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 auto- matic layer control system.
Melt pool monitoring, in which the ma- chine will monitor and record the properties of the pool of molten metal at the powder bed, is another quality feature SLM has been testing. This data can be evaluated to look for variances that might affect part quality. The next stage of development will be to use the information collected to actu- ally control the process, Fendrick said.
Certification × 2 Operating a facility certified in metal
production, and having certified pro- cesses 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. Tapping into an infrastructure of advisors knowledgeable about metal AM part certification and ISO approval for a metal AM shop is still tricky, though.
EOS’ Snow said his company provides continuous train- ing to clients to help them get the most out of their ma- chines. He advises users to work with their OEM to under- stand the technology better and learn how to optimize it. One challenge for working with metal AM is establishing
This model turbine assembly for GE was made with an SLM metal AM machine.
a process that yields the desired results of accuracy, surface finish, and material properties, and is repeatable. “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,” Fen- drick 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. “As these manufacturing companies adopt AM and bring it in house, actually having a facility that’s certified to do ad- ditive 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.” 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.
“A major challenge, the largest challenge, in the adop- tion 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.” 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.
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AdvancedManufacturing.org | May 2016 Metal Hazards
When working in AM, experts recommend wearing heavy-duty personal protection equipment to keep opera- tors 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 fire- proof lab coat, having a Class D fire extinguisher that can put out metal fires, and properly disposing of the machine’s filters.
Photo courtesy of GE
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