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The aerospace industry can increase productivity by optimising conventional manufacturing methods or using new ones
18 Dec 2020
The aerospace industry is very interested in new alternative manufacturing methods. This interest is driven by the desire to produce components using superalloy 718 as efficiently as possible. Research by Jonas Holmberg, an externally employed doctoral student, has shown how conventional methods can be streamlined and how new alternative methods can further increase productivity.
At the start of December, Jonas Holmberg defended his doctoral thesis on strategies for manufacturing aircraft engine components. His research findings grew out of advanced studies and comparisons of conventional and alternative manufacturing methods. The results are also applicable to additive manufacturing. Jonas conducted these studies in collaboration with GKN Aerospace in Trollhättan.
“Conventional milling is the current technique for manufacturing aircraft engine components using superalloy 718. But this process is often time-consuming, involving relatively small depth of cut in order to prolong the lifetime of the cutting tools. Yet, methods exist that show promise for this type of manufacturing, which allows for significantly reduced manufacturing time, but they aren’t as well-tested.”
Three new methods compared
Aircraft engine components are often made using superalloy 718 – a high temperature alloy that sets extreme demands on the manufacturing.
“I examined both how conventional methods such as milling can be optimised and what is necessary for the alternative manufacturing methods to be able to meet the same high-quality requirements. I then compared the methods and identified the most suitable strategy for achieving optimal productivity when manufacturing aircraft engine components.”
Jonas has tested and compared three different manufacturing methods: abrasive water jet machining (AWJM), laser beam machining (LBM), and electrical discharge machining (EDM). The studies showed that two of them are most suitable.
“My research has shown that abrasive water jet machining and electrical discharge machining are the most promising when it comes to manufacturing aircraft engine components. Although the surfaces still need finishing to meet current requirements.”
Abrasive water jet most promising
“The results have shown that conventional rough milling methods can be optimised by ensuring suitable machining allowance, with the aid of a methodology developed during this research, for determining surface impact. However, to streamline manufacturing even further, alternative methods are necessary. Abrasive water jet machining has shown the greatest potential for this, since it can cut rapidly and is suitable for components with complex geometries.”
“One of my conclusions is that the best combination for increasing productivity is to use abrasive water jet or electrical discharge machining for milling, and then follow up with a surface treatment using conventional finishing milling. But there are also many other interesting options for finishing.”
Continuing with advanced studies
Jonas will continue his research of new manufacturing methods at the RISE Research Institutes of Sweden. Over the past twelve years he has worked here on a variety of research projects and assignments from industry in parallel with his doctoral studies.
“My doctoral studies have been a journey during which I have learnt new approaches and gained a deeper understanding of researching. The fact that my research has been evaluated by external parties has been incredibly beneficial – and naturally, it feels great that my research can benefit the aerospace industry and other manufacturing industries.”
Link to Jonas Holmberg’s thesis: “High volumetric machining strategies for superalloy gas turbine components”
Contact details: jonas.holmberg@ri.se, tel.: +46 70 780 60 72