Session: 03-04-02: Advanced Machining and Finishing Processes

Paper Number: 145972

145972 - Post-Processing of Additively Manufactured Ss316 Employing Die Sinking Edm 

Selective laser melting (SLM) stands out as an additive manufacturing (AM) technique enabling the production of highly complex, fully functional metallic parts using computer-aided design (CAD) models. Along with these advantages, SLM offers disadvantages such as poor surface roughness, unevenness, and average mechanical properties. Additionally, they often contain significant tensile residual stresses in the near-surface layers, leading to microscopic defects and cracks on the surface. Consequently, secondary processing of metallic AM components becomes crucial for attaining the desired surface quality and enhancing the mechanical properties of SLM printed parts. Numerous surface treatments were reported in the literature, both conventional (milling) and non-conventional (laser polishing, chemical polishing, abrasive finishing, and Surface Mechanical Attrition Treatment (SMAT)). However, these secondary surface treatments face challenges such as significantly extended processing time and complications in finishing complex shapes. Furthermore, their applicability is limited to certain materials. Although hybrid methods can impart good surface integrity and properties, they require complex and expensive setups for finishing. In this study, an unconventional technique, Die-sinking electro-discharge machining (EDM), has been proposed to improve the surface integrity of SLM-printed SS316. Electrical Discharge Machining (EDM) is an unconventional, non-contact machining technique in which the material is removed from the workpiece with the help of successive sparks between the workpiece (cathode) and tool (anode). Stainless Steel SS316, an austenitic chromium-nickel stainless steel containing deliberate amounts of molybdenum, exhibits enhanced general corrosion resistance. SS316 is preferred for pharmaceutical equipment, chemical and petrochemical processes, pulp and paper, and food industries. This study investigates the effect of process parameters (Ip, Ton, and Toff) on the surface integrity of SLM-printed SS316 employing die-sinking EDM. The brass electrode was used for machining to limit surface roughness and improve surface properties. The average surface roughness of SLM printed SS316 was 8.26μm. A thorough examination was undertaken to scrutinize the surface finish and morphology and evaluate the enhancement in surface integrity resulting from die sinking EDM. The results of experiments manifest that at higher levels of pulse current (25 A), pulse on time (80 μs), and pulse off time (90 μs), the surface roughness of the SLM printed specimens (SS316) was improved to 3.19μm.

Scanning electron microscopy (SEM) reveals larger crater size, more crater overlapping, and surface burns. The material removal rate evaluated for this particular pulse energy was 0.00409 mm³/s. After the surface treatment process, EDS analysis divulged the migration of a minimal amount of tool material to the SS316L workpiece surface.

Presenting Author: Asma Perveen Nazarbayev University

Presenting Author Biography: Dr. Asma Perveen is an Associate Professor in Mechanical & Aerospace Engineering department at Nazarbayev University (NU), Kazakhstan. Dr. Perveen earned her PhD from National University of Singapore (NUS) under Mechanical Engineering Department in 2012. After completion of her PhD, she worked as Research Scientist at Singapore Institute of Manufacturing Technology (SIMTech) for more than two years. She also worked as Visiting Research Scholar in University of Parma, Italy and Western Kentucky University, USA. Her research interests are on the areas of EDM, hybrid Machining processes, Additive Manufacturing, Polymer extrusion and non-conventional machining processes. She has served as technical committee member, Co-Convener, Convener, session chair for several conferences. She is currently serving as Reviewer and Editorial board member for several reputed journals. Apart from original research publications, she has also published several books chapters in different manufacturing research-oriented books published by Springer, Elsevier, Nova science etc.

Authors:

Shahid Ali Nazarbayev University
Didier Talamona Nazarbayev University
Asma Perveen Nazarbayev University