Microanalysis of debris formed during rotary EDM of titanium alloy (Ti 6A1 4V) and die steel (T 215 Cr12)

The present investigation attempts to focus on the influence of EDM energy input on the structure and composition of the debris that forms during machining. An indigenously prepared ZrB2-Cu composite and mild steel plate were used as tool and workpiece (WP) material for the present study. The machining was carried out in a kerosene medium. The composition analysis of different debris particles was investigated by SEM/EDS. At low EDM energy input the SEM micrographs of WP debris showed formation of smaller size particles with few satellites. The SEM micrographs of high EDM energy input showed formation of hollow spheres, with dents, larger population of satellites, surface cracks and burnt core structures.

Microanalysis of debris formed during electrical discharge machining (EDM)

Hydrogenation of nanocrystalline Zr–Fe–H powder

In this bipartite study, waste products of die-sink electro discharge machining (die-sink EDM) are investigated. EDM is based on an erosive character of discharges leading to material removal and molten material congeals in the dielectric. The aim is to show a theoretical suitability of these particles for a further usage as a secondary, recycled material in additive manufacturing (AM). Due to the energy- and cost-intensive process of gas atomization for AM powders, there is a need for alternative concepts for particle generation. The first part deals with an intensive review of references from the literature regarding particle size and circularity using image analysis. Secondly, real waste streams were investigated after washing and cleaning processes for oil removal via laser diffraction, dynamic image analysis, SEM with energy dispersive X-ray spectroscopy (EDX) as well as optical emission spectroscopy (ICP OES), categorized within the literature and compared to commercial AM powders. In general, it could be shown that, in principle, recycled particles fulfill main requirements for an AM usage regarding size and shape. Reference powders show median particle sizes of 30 µm to 34 µm and circularities of 0.90 to 0.93, whereas eroded particles exhibit an x50 value of 27 µm and circularity of 0.90, too. However, chemical purity, mainly caused by carbon contamination (5.4 wt% in eroded powder compared to 0.4 wt% in reference powder), must be improved before printing via AM machines. Additionally, several separation techniques have to be applied to remove undesired elements (alumina).

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Suitability of Eroded Particles from Die-Sink Electro Discharge Machining for Additive Manufacturing—Review, Characterization and Processing

Influence of Liquid Composition and Discharge Energy on Process Productivity, Composition and Properties of Particles Produced by Electric Discharge Erosion of WC–5TiC–10Co Alloy

When two electrodes are immersed in close proximity in a dielectric fluid, connected to a pulsed power source, and the field strength in the gap is sufficiently high, a spark is produced as a result of the breakdown of the dielectric. In the present study, fine particles of various metals have been prepared by spark erosion in various dielectrics. Instead of the usual tool/workpiece arrangement used in electrodischarge machining, two electrodes with pieces of charge between them were employed to increase the powder production rate by at least two orders of magnitude. Powders of alloys, semiconductors, and compounds have been prepared, and it is shown that spark erosion can maintain a high production rate at low power consumption if the electrode/charge arrangement is used. PM/0479

J. L. Walter

Papers

Preparation of Powder by Spark Erosion