This study investigates the effects of electro-discharge parameters on the surface integrity in small-hole drilling. Discharge current, pulse on-time and pulse off-time were chosen as variable parameters. The gap voltage, dielectric flushing pressure, electrode rotation, electrode polarity and capacitance were taken as constant. Material removal rate, surface roughness, average white layer thickness, overcut and taper were taken as outputs for this study. Experiments were performed on DIN 1.2080 (X210Cr12) cold working tool steel, and ∅2 mm single-hole brass electrodes were used. The experimental results indicate that a compromise solution is required in selection of the electrical discharge machining parameters (i.e. discharge current, pulse on-time and pulse off-time) to maintain machining stability (melting–evaporation and removal of debris). As the stability is maintained during the process, dimensional accuracy increases and a better finish can be obtained with a reasonable machining time.

In this article, the effect of abrasive types on the abrasive flow machining process was investigated. Four groups of abrasive media were prepared with different types of abrasives: SiC, AL 2 O 3 , B 4 C and Garnet. An experimental study was performed on DIN 1.2379 tool steel. The specimens were cut using wire electrical discharge machining and finished with the abrasive flow machining process. The results show that the white layer that formed during wire electrical discharge machining was successfully removed by abrasive flow machining in a few cycles. Although the surface roughness improves with similar trends for all media groups, the results show that the media prepared with B 4 C and SiC have more surface improvement than the Al 2 O 3 and Garnet ones. The resulting average surface roughness (R a) values are comparable to the surface quality of those obtained from lapping and super-finishing. The material removal is directly related to the hardness of the abrasive.

Abrasive flow machining (AFM) is a manufacturing technique that uses the flow of a pressurized abrasive media to remove workpiece material. In comparison with other polishing technique, AFM is very efficient, suitable for the finishing of complex inner surfaces. In this paper, the effect of workpiece hardness on the AFM process has been investigated. An experimental study was carried out on AISI D2 tool steel hardened to 31, 45 and 55 HRC. The specimens were cut by using wire electro discharge machining (WEDM) and then finished with AFM. The results show that the white layer formed during WEDM is successfully removed by AFM in a few cycles. Although the surface quality is improved by AFM for all hardness groups, the results show that harder materials have more surface improvement than the softer ones.

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This study presents an experimental investigation of small hole electrical discharge machining of Al-Mg-Ti alloys. A series of drilling operations were carried out for exploring the effect of magnesium content. Holes of 2 mm diameter and 15 mm depth were drilled using tubular single-hole rotary brass electrodes. The rates of material removal and electrode wear, surface roughness, overcut, average recast layer thickness, taper height and angle were studied for Al-Mg-Ti alloys contain 2%, 4%, 6%, 8%, 10%, 12%, and 14% Mg. The results show that the material removal rate is increasing with increasing Mg content while the rate of electrode wear is almost unchanged. Due to decreasing the melting temperature of the Al-Mg-Ti alloy with increasing Mg content, more metal melts and vaporizes during electrical discharge machining drilling. Therefore, more overcut and taper, thicker white layer, and rougher surfaces were measured for higher Mg content.