Iowa Gov. Kim Reynolds helped cut the ribbon on the opening of Collins Aerospace’s expansion of its additive manufacturing center in West Des Moines, Iowa, yesterday. The $14 million expansion adds 9,000 sq ft to the center, which will enable Collins to explore development of additive manufacturing production for commercial and military aircraft engine components, supplementing manufacture of engine components already underway for industrial turbine engines. The West Des Moines facility specializes in design and production of engine components.
Collins began additive manufacturing at the site in 2016 with a single-laser machine that was used for research and development of the process. The latest machine installed in the facility is a 12-laser SLM Solutions NXG XII 600 that can manufacture complex components—basically anything that could fit inside a 600-cu-mm cube.
The machine builds parts by laying down a 60-micron-thick layer of metal powder, generally aluminum but it varies depending on the part. The 12 lasers sinter (weld) points on each layer, corresponding to the requirements of the design, and this is done layer by layer, thousands of times. One part might require as many as 1,800 layers. Once done, the part is moved out of the machine so the next part can be made, then the finished part goes to a depowdering station for removal of all the tiny powder particles by agitation and vibration. The captured powder is tested and cleaned of contaminants and placed back into rotation for reuse.
After depowdering, the part goes into a Jayco cleaning machine, which uses Simple Green soap and water to clean the part. Next is final shaping using an electrical discharge machining tool to remove excess metal, followed by heat treating.
Various types of testing are next, including material testing and checking the powder distribution. Some parts are tested to destruction using a torsion-testing rig, in which case portions of the metal can also be examined for inclusions, density, and porosity before freezing the design. Next is non-destructive testing using fluorescent penetrant inspection and x-ray and computerized tomography scanning. Finally, quality control technicians use coordinate measuring machines, which measure dimensions with physical probes, and a 3D scanning system that does dimensional checking with light.
Compared to traditional metal casting, forging, and machining processes (also called subtractive manufacturing), additive manufacturing can reduce part count by up to 75 percent because it can replicate complex designs without needing mechanical fastening of separate pieces and extensive machining and finishing processes. The ratio of metal versus scrap for traditional manufacturing is about 20 to one, where additive manufacturing, thanks to the ability to capture and reuse a lot of the powder, is one to one or 1.5 to one, although powder is more expensive than raw metal. But in any case, additive manufacturing eliminates most of the time spent corralling scrap metal, storing it, and sending it for energy-intensive recycling.
Another additive manufacturing benefit is a great reduction in lead time. Some components require casting and forging lead times from various manufacturing suppliers of six months to a year, but making the same component using additive manufacturing reduces the time to just weeks, the limiting factor usually being the availability of the metal powder. The SLM machine can make parts 24/7.
Typical parts that Collins is making at the West Des Moines facility are turbine engine nozzles. The company isn’t making rotating turbine parts yet, but that could be in the facility’s future as there is room to add more SLM machines in the expansion and also space available to add another 10,000 sq ft.
The facility is certified under the National Aerospace and Defense Contractors Accreditation Program, one of only eight in the U.S. to receive that certification.
“From supporting the backlog in commercial aircraft to enabling future platforms, and reducing carbon emissions to providing supply chain relief, additive manufacturing is poised to play an integral role in the future of the aerospace and defense industry,” said Renee Begley, West Des Moines site lead for Collins Aerospace. “Additive manufacturing has the potential to help us reduce weight, complexity, lead time, and cost in the parts we supply, and this expansion represents an investment in our business to help deliver those benefits to our customers.”