Every few years, there is a rush of enthusiasm regarding 3-D printing technologies (see for example http://www.economist.com/node/18114221.) Each time this topic comes around, I have the same set of questions and wonder if this is the time it will experience explosive growth and substitution for conventional fabrication technologies. My questions are usually around materials, precision/resolution and cost. What range of materials are suitable to this type of 3-D printing technology (plastics, metals, composites, etc.)? How precise is the “machining” and how reproducible are successive pieces? How much does it cost per piece (setup, first piece, first 10, 100, 1000, 10000, etc.) and how does this cost compare to conventional fabrication technologies? What are the technology trends for 3-D printing (cost, precision, materials) compared to the steady improvement in CAD/CAM?
Earlier 3-D printing technologies were dependent on the peculiar properties of particular classes of polymers or gels. The object formed by the printing was the right shape, but usually the wrong material. The subsequent step of creating a mold from the printed object and molding in the preferred material reduced the appeal of the 3-D printing process.
This most recent economist article, like many I’ve see over the years, is fully of vision and technology salesmanship, however, there are a couple of details that are more than just boosterism that may indicate that more widespread adoption will happen in a few years. The first is a material... titanium. Titanium has always been a problem material. Light, strong, creep and crack resistant, with a high melting temperature, it has been a preferred material for supersonic airframes since the days of the SR-71 Blackbird. However, it is difficult to machine (requiring an inert atmosphere and special tooling) and one fabrication technique for titanium has involved sintering... placing titanium powder in ceramic molds at very high temperatures until the powders fuse at the edges into a solid material. The quality of the piece is dependent on process trade secrets. My understanding is that there is a lot of art in the fabrication of titanium.
EADS engineers in Bristol, have been using lasers and/or electron beams to print 20-30 micron layers of titanium power into fused structures and then add layer by layer to make titanium parts. This sounds like a technology that could work for any powdered metal that you might want to fabricate. Aerospace parts using titanium or titanium alloys could be the breakthrough application for the technology.
The second detail is an interview with Dr. Neil Hopkinson at Loughborough University that discusses an ink-jet technology his team has invented that prints an infra-red-absorbing ink on polymer powder and then uses infra-red heating to fuse the powder layer by layer. This is sintering (at low temperatures) applied to polymers and should be useful for a variety of polymer compounds. Dr. Hopkinson thinks their process is already competitive with injection-molding at production runs of around 1000 items and expects it to be competitive on 10,000 to 100,000 item runs in about 5 years. This is the key economic comparison for adoption.
What do you think of 3-D printing? Is the time now, soon or much later in your technological crystal ball?
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