Abstract
Development of future aero engine components based on new design strategies utilising topological optimisation and additive manufacturing has in the past years become a reality. This allows for designs that involve geometries of “free form” surfaces and material combinations that could be difficult to machine using conventional milling. Hence, alternative manufacturing routes using non-conventional high energy methods are interesting to explore. In this investigation, the three high energy machining methods abrasive water jet machining (AWJM), electrical discharge machining (EDM) and laser beam machining (LBM) have been compared in terms of surface integrity to the reference, a ball nosed end milled surface. The results showed great influence on the surface integrity from the different machining methods. It was concluded that AWJM resulted in the highest quality regarding surface integrity properties with compressive residual stresses in the surface region and a low surface roughness with texture from the abrasive erosion. Further, it was shown that EDM resulted in shallow tensile residual stresses in the surface and an isotropic surface texture with higher surface roughness. However, even though both methods could be considered as possible alternatives to conventional milling they require post processing. The reason is that the surfaces need to be cleaned from either abrasive medium from AWJM or recast layer from EDM. It was further concluded that LBM should not be considered as an alternative in this case due to the deep detrimental impact from the machining process.
Highlights
1.1 Background and objectivesHigh speed milling with ceramic tools followed by different tempos using cemented carbide tools into a final geometry is the conventional manufacturing method of aero engine parts today
The results showed that a recast layer (RCL) of 5–9 μm was generated regardless of the settings, and further, it was observed that the surface roughness mainly was affected by the energy per spark
This measurement gives the possibility to parameterise the amount of deformation which showed that the milling resulted in the highest deformation compared to electrical discharge machining (EDM) and abrasive water jet machining (AWJM)
Summary
High speed milling with ceramic tools followed by different tempos using cemented carbide tools into a final geometry is the conventional manufacturing method of aero engine parts today This production route is often problematic and time consuming due to the materials’ high resistance to be machined. New and emerging technologies involving additively manufactured material, topologically optimised designs and fabrication of parts offer a more material resource efficient production compared to the traditional one where large castings are machined to final shape [2,3,4] For such manufacturing, conventional milling could be problematic because it involves machining of difficult geometries as well as materials that may have different properties. With high energy methods, this machining could be made possible in one setup
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