'Subtractive' Industries Are Coming to Terms with Additive Manufacturing

GE said additive manufacturing enabled a single-piece fuel nozzle design that got rid of 20 components that would have required assembly.   GE said additive manufacturing enabled a single-piece fuel nozzle design that got rid of 20 components that would have required assembly.

Additive manufacturing is on a roll. Also known as 3D printing, AM has been around for three decades, but it has finally begun an entrenched march into mainstream manufacturing. The advent of part-making platforms that combine "subtractive" machining capabilities with printing technology is the latest and most promising step to date for additive manufacturing, serving as efficient, hybrid means of fabricating and finishing parts in one setup.

AM's continuing evolution toward becoming a mass-production technology was in abundant evidence at the International Manufacturing Technology Show in Chicago back in September. The presence of hybrid printing-machining systems at IMTS gave attendees a look at potentially one of the most important directions manufacturing will take in coming years. While the much-publicized laser-sintering construction of a completely 3D printed body for a one-off electric car over a span of 44 continuous hours acted as a show centerpiece for AM's continuing long-term aspirations, all over the show there were presentations, technical discussions, and exhibits of "real-world" parts and applications being produced with additive manufacturing right now -- and by small manufacturers in some cases.

Timeframes in the AM realm are still associated with custom or low-run orders and not mass production. But in the slowness of AM processes -- especially for large single parts -- manufacturers are seeing a counterbalancing payoff in the ability to "design for process." AM is enabling the realization of complex parts and molds and tooling, in addition to one-off replacement parts and the requisite detailed prototypes for which the technology has been known since its beginnings.

Baklund R&D LLC, a 14-person tool and die maker and precision machine shop in Hutchinson, Minn., has dove into 3D printing for both internal use and expanding its revenue streams; the shop uses it to grow jigs and tooling plates, among other functions. "My guys are thinking differently with parts. They sit down and talk about it," said president Jon Baklund. "You think about how you design a part to reduce stress, and it opens up creativity," he noted of AM.

Already, the reshaping of the way parts are thought up and designed is occurring at both small and large manufacturers. GE's use of AM to put 19 printed fuel nozzles into each of its LEAP jet engines is a much-talked-about example at the elite end of the design spectrum. The LEAP fuel nozzles are up to 25 percent lighter and five times more durable than traditionally manufactured nozzles, GE claimed, due to the elimination of complex assemblies with 20 components with design-optimized single pieces.

"The best economic benefit is when designing to the process, eliminating assembly articles in a part," said Alex Fina, general manager of RTI Directed Manufacturing, a laser sintering facility in Austin, Texas, that provides rapid prototyping and short-run rapid manufacturing services. "Aerospace complexity is a really good fit for AM."

As highlighted by GE, the aerospace market is a pivotal one for AM's success. The use of advanced metal powders such as titanium and alloys allows fabrication of parts, including high-pressure turbine blades, on an as-needed basis, in rapid-manufacturing-based repair applications.

Elsewhere, AM is being used to create tool and die inserts with conformal cooling channels that reduce part stress and molding cycle times for injection molded parts, as with the case of Linear Mold & Engineering, in Livonia, Mich. "We grow water lines, layer by layer, for the inserts in the mold that follow the part, not the mold, to solve molding hot spots in the parts," said Lou Young, new business development director. "We've merged the moldmaking shop with AM."

"Injection mold inserts are one of the coolest applications of AM," noted Andrew Snow, senior vice president of North America for AM equipment maker EOS, adding that lightweighting applications in aerospace -- with a recent Airbus door hinge being an example -- and growing internal part features are expanding areas, as well. "AM is a design-driven technology, not a manufacturing-driven one like we learned, and this will float down from the Tier Ones to the job shops."

The global market is small but growing, and could reach $8.5 billion by 2020, according to projections from one source, controls giant Siemens, which has collaborated with DMG Mori on hybrid manufacturing equipment.

While the aerospace industry naturally continues AM work with large, highly complex structural parts for low-quantity runs, AM is ironically ideal for making extremely small parts on a mass scale. One example is dental coping, the substrate that connects a cap or crown to a tooth. Several hundred of these, each with individual dimensions, can be fabricated on a machine overnight.

Hybrid manufacturing machines like the LASERTEC 65 3D from DMG Mori can increase the output of additive manufacturing processes. Hybrid manufacturing machines like the LASERTEC 65 3D from DMG Mori can increase the output of additive manufacturing processes.

Since AM remains for now a specialty technology, equipment suppliers see hybrid manufacturing as a way of fine-tuning the efficiency and economy of the process, as well as promoting synergies with machining that could drive applications. The reality is, additive manufacturing is not yet a net-shape process and requires finish machining. "Subtractive and additive have to co-exist, there's no way around it," EOS' Snow remarked.

Recent hybrid manufacturing equipment introductions by Mazak, DMG Mori, Matsuura, and Flexible Robotic Environment (FRE) show that machinery suppliers are interested in AM and will refine it to broaden end-use potential.

DMG Mori, for example, showed the LASERTEC 65 3D at IMTS, a hybrid machine that combines laser deposition welding with 5-axis milling. It has a metal-powder nozzle that speeds deposition by a factor of 10 compared with building parts up in a powder bed. The reported deposition rate is a robust 1 kg (2.2 lb)/hr. The milling system can be used to machine a part to final dimensions once the laser welding is done, or interspersed with the welding process to finish areas that might not be accessible once AM is completed.

An important aspect of the machine's operation is automation. The machine and process are controlled by the company's CELOS real-time adjustable control platform and Siemens' Sinumerik 840D software. Company videos show how quickly and accurately the hybrid platform switches from laser welding to milling and back again.

Automation, in fact, is an important enabling technology in hybrid manufacturing -- not only within the machine via automatic tool changers and alternating AM/milling operations but in the adjacent area. One way to increase throughput will be to link hybrid manufacturing with lights-out production. Developing machines and support systems that give hybrid manufacturing platforms the ability to operate 24/7 on an unsupervised basis will be an important step towards increasing output.

FRE, which specializes in automated systems, recently introduced its 6-axis VDK6000 Robotic Work Center. The system, essentially a large work cell, integrates AM, machining, and in-process quality operations, e.g., laser scanning for reverse engineering and ultrasonic inspection. The company said the idea behind the Robotic Work Center is to clamp a part in place once and perform different operations on it until it is finished.

The democratization trend in automation will doubtlessly influence the acceptance of hybrid manufacturing by machine shops. As more techniques become available to speed AM operations and integrate them seamlessly within hybrid manufacturing centers, a growing number of shops will find that the technology, while a specialty, is vital to competitiveness and their bottom line.

"Everyone is thinking about this technology," said Alex Chausovsky, senior principal analyst for industrial automation at IHS. "Speed still needs to be worked out, and there are cost and size limitations, but is there an opportunity? What am I going to do with it?" he said about AM piquing manufacturers' interest.


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