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Metal matrix composite (MMC) is a combination of two or more materials using metal as a matrix. In this paper we used brass as the matrix and fly ash as for the particle. The fly ash used is fly ash which is produced from coal combustion in the Paiton power plant. Fly ash composition in the MMC are 5% and 10%. The MMC was produced with gas furnace. Heat tratment to MMC was done at 350 and 400 C.Hard testing process, tensile test and impack test are carried out at MMC before heat treatment and after heat treatment. From the test results showed an increase in hardness, tensile strength and impact test showed the heat treatment process at a temperature of 350 C. Heat treatment at a temperature of 400 C does not improve the mechanical properties of MMC

AbstractThe machinability information of Zr-based bulk metallic glasses (BMGs) are recently limited but essential to provide technological recommendation for the fabrication of the medical devices due to the material’s metastable nature. This study aims to investigate the material removal rate (MRR) and surface roughness under different current and pulse-on time of newly developed Ni- and Cu-free Zr-based BMG using sinking-electrical discharge machining (EDM). By using weightloss calculation, surface roughness test and scanning electron microscopy (SEM) observation on the workpiece after machining, both MRR and surface roughness were obtained to be increased up to 0.594 mm3/min and 5.50 μm, respectively, when the higher current was applied. On the other hand, the longer pulse-on time shifted the Ra into the higher value but lower the MRR value to only 0.183 mm3/min at 150 μs. Contrary, the surface hardness value was enhanced by both higher current and pulse-on time applied during machining indicating different level of structural change after high-temperature spark exposure on the BMG surface. These phenomena are strongly related to the surface evaporation which characterize the formation of crater and recast layer in various thicknesses and morphologies as well as the crystallization under the different discharge energy and exposure time.

The purpose of this study is to gain insights into the surface quality (smoothness) of sinking EDM machining products. Among other non-conventional machining processes, Electrical Discharge Machining (EDM) is the most commonly used process. EDM is a machining process that uses electric sparks created between a workpiece and a tool (electrode). As a manufacturing process, EDM is used for workpieces which have intricate contours and precise dimensions, and works by using electric discharges (sparks) applied in a rapid series of repetitive electrical discharges between the two electrodes, separated by a dielectric fluid, and subject to an electric voltage. Since the tool tends to wear easily and the mould material is very hard and tough, it is necessary to keep within appropriate EDM machining parameters, so that the smoothness of the mould lives up to expectations. Therefore, the parameters of sinking EDM process should be well established to produce the expected results, i.e. the smoothest surface quality and the maximum removal rate. Regarding the electrode materials used, conducting a further experiment is required to achieve the appropriate settings of pulse current, on-time, off-time, servo voltage, and gap width. This experimental study involved several factors: (a) electrode material, (b) magnitude of current, (c) on-time, and (d) quality of surface (smoothness). In this study, the gap between the electrode and the workpiece was controlled at a distance of 40 μm, and with an off-time of 5 seconds, the same dielectric fluid, the same flow speed and the same dielectric immersion, and using the workpiece (AISI P20M steel). Quantitative approaches (t test, one-way, and ANOVA) were applied to analyse the results of comparison test and to determine the best parameter in sinking EDM process.

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