Page 24 - 3D Metal Printing Summer 2016

3D
Titanium
Titanium
Taking Off
Taking Off
FEATURE
Machining titanium into aerospace parts can create a buy-to-fly ratio upwards of 10 to 1, as machine shops turn expensive metal into chips. Often 3D metal printing makes more sense, but only as long as titanium-powder producers can meet the growing demand for powder that’s fit for metal printing. BY BRAD F. KUVIN, EDITOR
From bicycles to airframe and engine parts, from automotive structures to dental implants, additive manufacturing with titanium powders is taking off. Called a “miracle metal” in some circles for its unique combination of properties, titanium and its cast and wrought alloys offer designers solutions to often challenging combinations of requirements for strength, shape memory, corrosion resistance and biocompatibility.
At the same time, however, titanium alloys can prove quite difficult to fabricate and machine, and often are referred to as “difficult-to-machine” materials. Basic challenges fabricators face when machining titanium include chip-thickness vari- ability, heat stress, springback and buildup of residual stresses. Cutting tools can wear quickly and unpredictably, and high-quality machined surfaces can be difficult to acheve.
Better Buy-to-Fly
Solutions to overcome many of these challenges are available for fabricators, but at a high cost. So while machining of titanium can be a quite costly proposition, manufacturers do it all the time. This leads us to another issue that plagues the aerospace industry, and others manufacturing with titanium: the ‘buy-to-fly ratio’ that aircraft producers refer to is quite high. A fabricator might purchase 100 lb. of titanium, for example, and machine away 90 percent of it to make a part, turning expensive metal into chips for a buy-to-fly ratio of 10:1 (in this case).
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