Abstract
The heat generated during EDM melts the work material and thereby allows large amounts to be removed, but an unfavorable surface of a recast layer (RCL) will also be created. This layer has entirely different properties compared to the bulk. Hence, it is of great interest to efficiently remove this layer and to verify that it has been removed. The main objective of this work has been to study the efficiency of grit blasting for removal of RCL on an EDM aero space shaft. Additionally, x-ray fluorescence (XRF) has been evaluated as a nondestructive measurement to determine RCL presence. The results show that the grit-blasting processing parameters have strong influence on the ability to remove RCL and at the same time introduce beneficial compressive stresses even after short exposure time. Longer exposure will remove the RCL from the surface but also increase the risk that a larger amount of the blasting medium will get stuck into the surface. This investigation shows that a short exposure time in combination with a short grit-blasting nozzle distance is the most preferable process setting. It was further found that handheld XRF equipment can be used as a nondestructive measurement in order to evaluate the amount of RCL present on an EDM surface. This was realized by analyzing the residual elements from the EDM wire.
Highlights
In aerospace engine applications, structural parts often have large and complex geometries
It was observed that blasting with longest nozzle distance and longest exposure time has resulted in the largest amount of erosion
The surface residual stress measurements were performed at different grit-blasting positions on the front side of the shaft according to Fig. 2
Summary
Structural parts often have large and complex geometries. This layer becomes hard and brittle which cause microcracking of the surface layer (Ref 2, 3) with a typical thickness of the RCL of [10-20] lm. In the study by Li et al (Ref 4), the surface integrity of the RCL was investigated where a W-EDM surface of Inconel 718 was evaluated in terms of surface roughness, microhardness and chemical composition by energy-dispersive spectroscopy. In order to qualify grit blasting as a postprocess for EDM, the effects of the process parameters on the work piece with respect to surface integrity need to be fully understood, which has been the main objective with this investigation. A secondary objective was to investigate if chemical analysis of the surface can be used in order to qualify whether the surface is free from RCL or not
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
