September 03, 2012
Credit: MORRIS TECHNOLOGIES
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.