Cobalt chromium gets the credit. “The material built well, with a nearly 100% dense part, no cracking and it held tolerances,” says Greg Morris. “That really was the spark that got things moving. Our customers found they had an alloy they could work with in the real world.”
Morris is CEO of the family-owned Morris Technologies Inc. (MTI) in Cincinnati, which got started using stereo lithography to prototype plastic parts in 1994. The company expanded into computer numerical control machining. But its transition into producing solid metal parts for prototypes began in 2003 when it imported the German-made EOS M-250 extended direct metal laser sintering (DMLS) machine.
The U.S. is now the leader in additive manufacturing, which includes DMLS and uses 3D modeling software to build up a part in thin, horizontal cross sections, one layer at a time. This “additive” process makes the part without waste and offers the opportunity to produce complex geometries in a single piece. An equivalent casting might require 7-10 separate parts, says Morris. It also will be heavier.
“In aerospace, there are some complex geometries that cannot be made with an investment casting,” he says. DMLS has limits; it is not yet applied to high-temperature applications, he notes. But it is used in combustion-chamber parts, blades, blisks, tubing and stators.
Aerospace is among the most aggressive users of the process and provides the bulk of MTI's revenue, which is centered in aircraft engines but also includes industrial gas turbines, medical devices and rapid prototyping for research institutions.
“In the early years, the alloys were not super-robust,” Morris recalls. “They couldn't hold high temperatures and had stress issues.” But within two years of acquiring its first machine, MTI had moved up to a more advanced version and was working with cobalt chromium alloys. Applications using other alloys—titanium, stainless steel and aluminum—soon followed.
“Two years after we first began playing with cobalt chrome, we understood the technology was going to be formative,” Morris says. One consequence is the formation of Rapid Quality Manufacturing (RQM) as a manufacturing sister company, leaving MTI to handle prototyping and product development.
One of additive manufacturing's characteristics is surface roughness. RQM developed MicroTek Finishing, a micromachining process using five-axis cutting tools so roughness can be reduced, even on interior walls. Polishing varies from industry standard RA scales of 2-4, which are so highly polished they work for knee implants, to RA 300, which is equivalent of 60-grit sandpaper.
While engine makers constitute its core development and production business, Morris regards collaboration with researchers at nearby Wright-Patterson AFB, Oak Ridge National Laboratory, Lawrence Livermore National Laboratory and www.morristech.com).'s , as important for the company's development. MTI is spending about 3-4% of its annual revenue—nearly $750,000—on R&D. Some is process-oriented, such as work on low-oxygen production. But the majority is product focused. A current effort required proprietary modifications to its DMLS machines as it experimented with a new Aluminum 6061 (to learn more, go to
The alloy is of interest because of its high-temperature characteristics. The industry already has a 6061T6 suitable for extrusions and plate applications, but no equivalent for casting. MTI wants to fill that gap with DMLS and has attracted enough interest for beta testing in airframe component, engine manifold and space propulsion applications.
Morris has found that what the company does attracts smart, creative people. “The coolness of the technology—lasers, electron beams—really stimulates people,” he says. “Reality is getting close to science fiction in a lot of this stuff.”
Major production rates remain a frontier, so RQM's production runs remain small. The expectation is that another 2-3 years will be needed before significant production starts.
“I think there's a fair probability that we will see additive metals interest and demand outstrip the ability of the supply chain to keep up,” he says. “There's still a very large knowledge transfer that needs to happen. But that happens with machining, too. In aerospace, the vast majority of people have heard of additive manufacturing.”
But he worries that tax increases and more regulation will stifle the business environment.