PSI - Issue 10

E.L. Papazoglou et al. / Procedia Structural Integrity 10 (2018) 235–242 E.L. Papazoglou et al. / Structural Integrity Procedia 00 (2018) 000 – 000

241

7

Fig. 7. Cross section of EDMed surface for I P 24 A and T on 75 μ s (Discharge energy 54 mJ)

Fig. 8. Cross section of EDMed surface for I P 24 A and T on 100 μ s (Discharge energy 72 mJ)

Fig. 9. Cross section of EDMed surface for I P 27 A and T on 300 μ s (Discharge energy 243 mJ)

Fig. 10. Cross section of EDMed surface for I P 12 A and T on 500 μ s (Discharge energy 180 mJ)

1

th WL

3.57 E  

(7)

3



 0.34

WL

148 I T   

(8)

th

P on

with WL th in μ m, E in mJ, I P in A and T on in μ s. 4. Conclusions

The present experimental research aims to investigate the correlation between EDM parameters and machining results, for a common and widely used tool steel, namely AISI O1. The machining parameters, which have been used and changed over the experimental procedure, are the pulse current I P and the pulse-on time T on . The material removal ratio has been calculated, the surface roughness has been measured through two common used parameters Ra and Rt and finally microscope observations were carried out to determine the quality and morphology of the white layer, which is a featureless layer of recast material. From the described research procedure, the following conclusions can be drawn:  The increase of the mean machining power results a higher MRR, with the between them correlation being almost linear, while the increase of the nominal pulse discharge energy does not necessarily mean a higher MRR.  The MRR strongly depends on the combination of the machining parameters, i.e. I p and T on , for which there is an optimum combination, for the highest MRR and machining efficiency, keeping always in mind an existing limitation of the current density.  The surface roughness, i.e. Ra and Rt, depends on the machining parameters and particularly on the discharge energy. This dependence can be expressed through semi-empirical correlations, making possible a prediction of