Investıgatıon Of Surface Integrıty In Electrıcal Dıscharge Drıllıng Of Aerospace Alloys


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2017

Student: TOHID ABBASI

Supervisor: OĞUZHAN YILMAZ

Abstract:

In this study, surface integrity which was formed after electrical erosion of aerospace and aerospace alloys (EDM) was investigated. In the electrical erosion process, a workpiece with electrical conductivity is placed with the electrode in a way that they do not touch eachother by means of non-conductive dielectric fluid, and the desired geometry is created by removing the material in this way. In this study, two kinds of hard metal alloys, Ti-6Al-4V and Inconel 718, and 2 types of electrodes, copper and brass are used. Experiments in this thesis study were made using the same EEI processing parameters in order to make comparisons. The parameters used in the conducted experiments are discharge current as 12.5 A, dielectric fluid pressure as 100 bar, electrode rotation speed as 100 rpm, pulse on time as 25 μs and pulse off time as 12.5 μs. In this study, the diameters of drilled holes were measured with and it was detected that the smaller diameter electrodes formed wider holes. SEM photographs of Ti-6Al-4V alloy showed more surface cracks on the treated surfaces than Inconel 718 alloy. According to the surface roughness results, the surface roughness of Inconel 718 decreases in both electrodes compared to Ti-6Al-4V alloy.