ORIGINAL ARTICLE Stability of micro dry wire EDM: OFAT and DOE method Asfana Banu 1 & Mohammad Yeakub Ali 2 & Mohamed Abdul Rahman 1 & Mohamed Konneh 3 Received: 19 September 2019 /Accepted: 2 January 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020 Abstract Micro dry wire electrical discharge machining (μDWEDM) is an environmental-friendly machining process where gas is used as the dielectric fluid instead of liquid. In this process, certain modifications of wire electrical discharge machining (WEDM) are required during the machining operation for stable machining. In μDWEDM, the process is considered stable if the machining is continuous without any interruption due to wire breakage or wire lag. However, in the present state of the arts, stable and smooth machining process using μDWEDM remains a critical issue. Hence, the objectives of this research are to establish a stable μDWEDM process using two different experimental approaches: one-factor-at-a-time (OFAT) and design of experiment (DOE) method. The investigation was performed on a stainless steel (SS304) with a tungsten wire as the electrode using integrated multi- process machine tool, DT 110 (Mikrotools Inc., Singapore). Types of dielectric fluid, dielectric fluid pressure, polarity, threshold voltage, wire tension, wire feed rate, wire speed, gap voltage, and capacitance were the controlled parameters. The machining length of the microchannels was measured using scanning electron microscope (SEM) (JEOL JSM-5600, Japan). Analysis based on these two experimental approaches shows that stable μDWEDM process is achievable when the types of dielectric fluid, dielectric fluid pressure, polarity, threshold voltage, wire tension, wire feed rate, and wire speed remain as the fixed parameters while the capacitance and gap voltage remain as the controlled parameters. Keywords Dry EDM . DEDM . DWEDM . μDWEDM . OFAT . DOE . Plackett-Burman design 1 Introduction Electrical discharge machining (EDM) process has the ability to fabricate high-precision products for communication, aero- space, and automotive industries [1–6]. It is a thermal machin- ing process where the machined area of the workpiece is re- moved by the thermal energy created by the electrical spark [4, 7, 8]. The electrical sparking process is a repetitive and discrete process which is carried out in dielectric fluid [4, 7–9]. Dielectric fluid plays a significant role during the machin- ing process where it helps to improve the efficiency of the machining process, improve quality of the machined parts, and flush away the debris from the machining gap. Usually, the dielectric fluids are in the form of mineral oil–based liquid or hydrocarbon oils. However, these types of dielectric fluids have certain deficiencies that are related to fire hazard and environmental problems [9–12]. Therefore, the alternative to overcome this problem is to use gas dielectric instead of liquid dielectric during the machining process [3, 4, 9–11]. The idea of using gas instead of liquid as the dielectric fluid is not fully agreed by certain researchers because of the ero- sion effect. Normally, the erosion effect is small when the sparks are generated in the air due to the energy lost. Moreover, one of the key functions of the dielectric fluid is to restrict the spark generation where higher density of energy is achievable during the machining process. This mechanism is only applicable when the dielectric fluid is in the liquid form [13–15]. Normally, the dynamic plasma pressure rises and the bubble of vapour expands when the sparks are in the liquid * Mohammad Yeakub Ali yeakub.ali@utb.edu.bn 1 Department of Manufacturing and Materials Engineering, Faculty of Engineering, International Islamic University Malaysia, P.O. Box 10, 50728 Kuala Lumpur, Malaysia 2 Mechanical Engineering Programme Area, Faculty of Engineering, Universiti Teknologi Brunei, Tungku Highway, Gadong, Bandar Seri Begawan BE1410, Brunei Darussalam 3 Department of Mechanical and Maintenance Engineering, Faculty of Engineering, Fourah Bay College, University of Sierra Leone, Freetown, Sierra Leone https://doi.org/10.1007/s00170-020-04923-9 The International Journal of Advanced Manufacturing Technology (2020) 106:4247–4261 /Published online: 14 January 2020