metal-powder.net March/April 2014 MPR 41

additive manufacturing

Direct metal laser sintering could be ‘better than’ rapid investment casting for aerospace parts

Conventional design of the steel cast bracket (upper left) that was

environmentally assessed against the corresponding topology-

optimised design of the EOS titanium AM-made bracket (lower right

corner). Source: Airbus Group Innovations.

Waste produced as weighted by the “embodied” energy for each proc-

ess (in kWh). This way of presenting results conveys a stronger and

improved idea of the embodied cost of the material, non-organic wastes

for each alternative process, based upon their ability to be recovered

either by re-use or recycling. Source: Airbus Group Innovations.

Emissions of carbon dioxide through the static (i.e.,

manufacturing) phases of the different design options

(in kg CO2 eq.) Source: Airbus Group Innovations.

Take-down of the energy consumption for the different

processes benchmarked during the manufacturing

phase (in kWh). Source: Airbus Group Innovations.

According to an assess-ment carried out by EOS and Airbus, using direct metal laser sintering (DMLS) instead of rapid investment casting to create a aerospace part is more environmentally friendly and can cut costs.

The companies compared the lifecycle of a generic bracket benchmarking the DMLS process with a conven-tional casting process, and found that the use phase has by far the biggest impact in terms of energy consumption and CO2 emissions over the whole lifecycle of the bracket. CO2 emissions over the whole lifecycle of the nacelle hinges were reduced by nearly 40% via weight saving using DMLS, and the weight per plane could be reduced by up to 10 kilogrammes.

When using as an example a titanium bracket made using DMLS, the companies found that total energy consumption for creating the initial raw powder metal, then produc-ing the bracket in DMLS, was slightly smaller than the equivalent cast process steps (with the higher energy use of DMLS limited to the melt and chill cycle of its manufactur-ing profile and offset at the

same time by a significantly reduced build time).

Casting in this comparison also included the furnace oper-ation of burning a stereolithog-raphy (SLA) epoxy model, which uses more energy and generates greenhouse gases.

The DMLS process itself used only the material actu-ally needed to make the part – eliminating waste from sec-ondary machining and reduc-ing consumption of titanium by 25% over the cast application.

“DMLS has demonstrated a number of benefits, as it

can support the optimisation of design and enable subse-quent manufacture in low-volume production,” said Jon Meyer, additive layer manu-facturing research team lead-

er, in his final report. “In gen-eral, the joint study revealed that DMLS has the potential to build light, sustainable parts with due regard for the com-pany’s CO2 footprint.”

MPR0214_AM news 41 02-04-2014 10:56:13