Tool wear and workpiece overcut have been studied in electrical discharge machining process with rotational external magnetic field and rotational electrode. Experiments have been divided to three main regimes, namely, low-energy regime, middle-energy regime, and high-energy regime. The influence of process parameters were investigated on electrode wear rate and overcut. Results indicate that applying a magnetic field around the machining gap increases the electrode wear rate and overcut. Also, rotation of the tool has negative effect on overcut. 1. Introduction Materials such as tool steel, ceramic, metal matrix composite, and Inconel widely are used in die molding, aerospace, surgical and automotive industries. Machining of these materials by using traditional machining is difficult due to high wear and corrosion resistance, hardness, and toughness properties of them. Electrical discharge machining (EDM) is a nontraditional method which is used most commonly to machining of difficult-to-machine materials. Flushing the debris from the machining gap is one of the major challenges in EDM process. Accumulation of debris in gap space causes inactive pulses such as short and open circuit and arc. These types of discharges do not remove any material from the workpiece and damage the surface integrity of machined specimen. By considering these reasons, researchers focus on the methods which improve the flushing in EDM. Methods such as EDM with rotating tool electrode [1–6], ultrasonic vibration assisted EDM [7–10], and compaction of vibration and rotation of electrode [5, 11] were introduced to develop the flushing, the eroded particle in gap space and improve the machining performance. Few researches have investigated the effect of rotary tool on machining characteristics in EDM. Soni and Chakraverti [1] analyzed the effect of rotary electrode tool on the EDM of titanium alloy. They found that the rotary motion of the tool increases the MRR and electrode wear rate (EWR) in all levels of current and pulse on time. Mohan et al. [2, 3] conducted the experimental study on Al-SiC composite material. They showed that the rotary electrode improves the MRR and reduce the surface roughness. Kuppan et al. [4] investigated the effects of various rotational speed of electrode on inconel 718. Results show that the increasing of the rotational speed is effective factor in low discharge energy. Ghoreishi and Atkinson [5] studied the influences of vibration and rotation of electrode on machining characteristics in three levels of machining pulse energy. Saha and Choudhury
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