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As the part is printed, it will be


supported by lattice structures of the same material. Once printing is complete, the supports are removed by hand and/or CNC machin- ing. Research has shown objects created by powder bed fusion, with proper heat treatment, can exhibit physical and mechanical proper- ties similar to cast parts, though further studies are ongoing. “Te main difference is the grain


structure,” said Bry Ewan, product manager of metals, Stratasys Direct Manufacturing, Valencia, Calif., a service provider of additive and


advanced manufacturing including 3-D printing. “If you cut a DMLS part in half, the internal grain structure will look different when compared to a cast part. But if you’re using an alloy that can be cast, the part will behave just like its cast or forged cousin.” Similar to binder-based metal


printing methods, powder bed fusion has made significant inroads in the aerospace, medical and oil/ gas industries. (See the sidebar for a case study involving a hinge for the Airbus A320.) GE Aviation recently announced plans to invest $50 million to introduce high volume addi-


DIRECT METAL PRINTING TAKES FLIGHT


When EADS, the European Aeronautic Defense and Space Co. (since renamed Airbus Group), Leiden, Netherlands, was investigat- ing ways to improve manufacturing components in the Airbus A320 jet airliner, the DMLS process seemed an especially appropriate process to manufacture nacelle hinge brack- ets for the jet aircraft because the process allowed for design freedoms that could meet the industry’s empha- sis on weight reduction. EADS emphasized quality, costs and environmental effects when choosing a manufacturing process and creating an optimized design. EADS conducted tests that compared DMLS-produced titanium brackets with investment cast steel versions by measuring energy consump- tion over the entire lifecycle. DMLS proved a good fit because its


operational performance is an estimated 100 times more important than the part’s manufacturing phase. The optimized design decreased energy consumption over the whole life cycle of the brackets by almost 40%, despite the DMLS manu- facturing process requiring significantly more energy.


Next, the components’ operational phases were evaluated. Energy consump- tion decreases slightly when moving from rapid investment casting to the EOS plat- form but the real advantage of DMLS is that the process decreased raw material consumption by as much as 75%. “I see tremendous potential in DMLS technology for future aircraft generations, when it comes to both development and manufacturing,” said Jon Meyer, EADS research team leader.


The study from EADS focused on a single comparison between DMLS and investment casting manufacturing


process without dealing with scalability. However, the study showed a number of impressive results including:


Optimized design of the engine cowl- ing hinge allowed EADS to demonstrate the potential to reduce weight per plane by approximately 22 lbs. (10kg). The weight savings could reduce the CO2 emissions contributed by the door hinges by almost 40% over the life of the part.


Consumption of raw materials was reduced by 25% compared to rapid investment casting.


“DMLS has demonstrated a number of benefits, as it can support the optimization of design and enable subsequent manufacture in low volume production,” said Meyer. “In general, the joint study revealed that DMLS has the potential to build light, sustainable parts with due regard for the company’s CO2 footprint.”


tive manufacturing to its facility in Auburn, Ala. Tis facility will produce the 19 fuel nozzles in its LEAP jet engine via powder bed fusion. Te facility expects to increase annual pro- duction from 1,000 to 40,000 by 2020. “We spent years proving out this


technology for a critical component in the heart of the engine,” said Greg Morris, general manager, GE Aviation, of the nozzles, which will reduce weight by 35% and parts from 18 to one. “Now we are well posi- tioned to apply this technology to other components in the same harsh environment which could prove to


DMLS reduced part weight and improved fuel efficiency in the Airbus A320 jet.


The conversion from casting reduced CO2 emissions. May 2015 MODERN CASTING | 47


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