Florida-based KW Micro Power, which designs and manufactures high power density Auxiliary Power Units (APUs) for commercial aviation and military applications, has worked with nTopology, New York City, New York, USA, and Velo3D, Campbell, California, USA, to redesign the housing of an aerospace-grade compact turbogenerator using metal Additive Manufacturing.
KW Micro Power offers a range of micro generator products, each optimised for different uses. For landbound applications weight is not considered a big concern, but for APUs on board an aircraft or drone, lightweighting is said to be crucial.
By utilising nTopology’s software and Velo3D’s Sapphire metal Laser Beam Powder Bed Fusion (PBF-LB) AM machine, the engineering team were able to reduce the generator housing weight by 44% — from approximately 10.4 kg down to 5.9 kg using Aluminum F357.
“I think this is like the renaissance of engineering,” stated Enrique Enriquez, president of KW Micro Power. “In the past, we were always working from the outside. Now, we can control every aspect of the geometry of our designs and their microstructure.”
The design for AM process opened new opportunities for KW Micro Power, allowing the team to convert the empty shell into a conformal cooling channel, improving the thermal management of its high power density generator. The result was a 33% drop in maximum operating temperatures, while the external temperature of the generator dropped by 86% and down to 27°C, making it safe to the touch. Fuel was used as the heat transfer medium, preheating it from room temperature to 55°C and increasing the efficiency of the combustion process.
As a bonus, the original CNC machined housing can now reportedly be manufactured in a single piece with Velo3D’s metal AM technology. To achieve this result, the team removed unnecessary material by creating a hollow shell with a variable wall thickness. The entire process is said to have required only a few simple design blocks in nTopology software, was performed almost instantaneously without errors, and took less than a day’s work before the part was ready to manufacture.
Zachary Murphree, VP of Sales at Velo3D, commented, “This component is a testament to what can be achieved by aggressive engineering companies that leverage next-generation design and manufacturing tools.”