The Performance of Brass Electrode on Material Removal for Aluminium Composite in EDM Die-Sinking

Abstract

Abstract. This paper investigates the performance of brass electrode on the removal of aluminium alloys LM6 (Al-Sil2) in an electrical discharge machining (EDM) die-sinking. The machining parameters such as pulse-on time, pulse-off time and peak current were selected to find the responses on the material characteristics such as material removal rate (MRR), electrode wear rate (EWR) and surface roughness (Ra). Brass with diameter of 10mm was chosen as an electrode. Orthogonal array of Taguchi method was used to develop experimental matrix and to optimize the MRR, EWR and Ra. It is found that the current is the most significantly affected the MRR, EWR and Ra while pulse on time, pulse off time and voltage are less significant factor that affected the responses. Percentage optimum value of MRR increases to 3.99%, however EWR and Ra reduce to 3.10% and 2.48% respectively. Thus, it shows that brass having capability to cut aluminium alloys LM6. IntroductionBrass is one of the electrical conductive materials. Today, however, brass is seldom used as an electrode in EDM die sinking due to its high wear rate but it still good for machining materials for high speed small hole machines because it exhibits higher degree of stiffness and easier to machine than copper [1]. Even though, brass already used as an electrode but it is still not tested for cutting aluminium alloys LM6. It is known that LM6 which aluminium containing 12% silicon has good resistance to corrosion and excellent cast ability [2]. It is widely used in many fabrication devices due to its characteristics properties such as applications for motor housings, manifolds, marine components and pumping cases. Further, LM6 is also appropriate where sometimes castings require to be welded.Usually in die tooling, when materials used is hard, it becomes better for die tooling, however it would be difficult to cutting using conventional cutting tools [3]. Therefore, some others electrode materials were tested against the aluminium alloys LM6 like copper tungsten [4], copper [5] and graphite [6] which has yielded a good experimental result. A special advantage of EDM die-sinking offers compared to conventional machine where materials removed without any contact between electrode and workpiece. As a result, problems of vibration and mechanical stress can be eliminated during machining process [7].Even though, the use of die-sinking EDM focused on the cutting material having conductivity of an electric, the process capability of cutting alloys materials, becomes more challenges regardless of their hardness and toughness [8]. The most advantage of EDM die-sinking machine is that it can cut electrical conductivity material, free from burrs especially for stamping die that can be produced by EDM die-sinking with accurate dimension, low cost and fast processes [9].