New additive metal manufacturing technologies are increasingly challenging powder bed fusion by laser (PBFL), according to a recent report from Germany’s industrial consultancy Roland Berger. The report’s author, Bernhard Langefeld, believes these changes will increasingly affect production of medical equipment, aerospace parts, prototypes and small-lot production.
Langefeld says choosing additive manufacturing and selecting a specific technology depend on three basic factors: cost, part performance and lot size. PBFL costs have come down in recent years, but not nearly enough to match conventional production costs. Langefeld reckons that four-laser printers cut PBFL costs 40% from 2015 to 2017 and will reduce costs another 22% by 2019. Adding more lasers will increase speed and productivity, but lasers are the most complex part of a PBFL machine, so they add costs as well. One manufacturer plans to launch a 10-12 laser machine in 2020, which should test the net advantages of adding lasers.
Meanwhile, engineers are starting to look at other additive technologies.
First, powder bed fusion by electron beam, which uses the thermal energy of an electron beam to fuse regions of a powder bed.
Next is material jetting, in which droplets of molten metal or metal powder in a carrier liquid are selectively deposited.
Then there is material extrusion, which dispenses material through a nozzle to form a green part which is then sintered, or compacted, into the solid part.
Also under consideration is binder jetting, in which a liquid bonding agent is selectively deposited to join powder material and form a green part which is then sintered.
Finally, there is directed energy deposition using powder, which fuses powder material by melting, and directed energy deposition using wire, which fuses wire material by melting during deposition. The latter is similar to the patented rapid plasma deposition process Norsk Titanium is using to make structural titanium parts for the Boeing 787. Another Norsk partner, Spirit Aerosystems, expects 30% of the thousands of titanium parts it currently makes could be good candidates for plasma deposition.
Langefeld stresses that none of these alternatives will be best for all applications. “Choice of technology is always a tradeoff between lot size per part, part performance and cost,” he says.
The Berger consultant is also seeing progress in production of metal powder, critical to the economics and quality of additive manufacturing. Some firms, like the SMS Group, are now focusing on industry-scale high-purity metal powder production, while others will specialize in small-scale metal powder production for rapid prototyping of metal parts.
Langefeld stresses that fully exploiting the benefits of additive methods will require a software suite that seamlessly spans the entire additive cycle: design, optimization, production planning, print-file generation and programming the additive machines. Because predicting the characteristics of an additively manufactured part is difficult and depends on many factors, it will require very advanced simulation software.
Fortunately, Langefeld say both hardware and software firms involved in additive manufacturing are, through many mergers and acquisitions, starting to combine their capabilities.