Development of Arrayed Structures Using Reverse EDM (R-EDM)

In recent years, reverse electric discharge machining (R-EDM) has been developed as a method for the fabrication of arrayed structures which find applications in the fabrication of fins and component assembly. In this study, the feasibility of R-EDM process in the fabrication of arrayed features of Ø 3 mm and height 2 mm on mild steel has been studied through response surface methodology (RSM) based experimentation. The influence of machining parameters i.e., peak current (Ip), pulse-on time (Ton) and flushing pressure (Fp) on some of the vital response characteristics like material removal rate (MRR), surface roughness (SR), taper, cylindricity error and micro hardness and surface morphology of the pillared structures has been investigated. Further, a hybrid optimization method i.e., principal component analysis (PCA) based grey relational analysis (GRA) technique, is utilized to obtain optimal parameter combination with an aim to improve machining conditions for fabrication of arrayed features during R-EDM process. Analysis of variance (ANOVA) results shows that Ip has significant effect followed by Ton on MRR and Ip has major contribution towards SR, taper and cylindricity error. Micro hardness has maximum value in heat affected zone (HAZ). The optimal parameter combination based on PCA based GRA is found to be Ip = 10 A, Ton = 100 µs and Fp = 0.3 kg/cm2 which was further ascertained using confirmatory tes

Aplikasi android pembelajaran abjad Bahasa Jepun (JingoCat Apps)

Bahasa asing menjadi salah satu bahasa yang perlu dipelajari oleh pelajar Ijazah Sarjana Muda di Universiti Tun Hussein Onn Malaysia (UTHM). Pelajar yang mempelajari Bahasa Jepun sebagai satu kursus bahasa ketiga mempunyai masalah menguasai perbendaharaan kata (leksikal), struktur bahasa serta tatabahasa. Faktor masalah ini berlaku adalah disebabkan, perbendaharan kata (leksikal) yang asing bagi pelajar, menyebabkan sukar untuk dihafal dan diaplikasi dalam latihan sama ada latihan komunikasi atau latihan untuk membuat ayat (Noor Aizah Abas, 2009). Kajian ini bertujuan untuk membangunkan satu aplikasi android pembelajaran abjad bahasa jepun aras satu dan dua kepada pelajar UTHM khususnya dan umumnya boleh digunakan kepada mana-mana pengguna yang berminat. Aplikasi ini merupakan pembelajaran awal dalam mempelajari abjad Jepun di samping memudahkan pelajar untuk menguasai huruf Hiragana dan Katakana melalui aplikasi pembelajaran mudah alih berasaskan multimedia. Aplikasi android pembelajaran abjad jepun tahap 1 dan 2 (JingoCat Apps) mempunyai tiga menu utama iaitu Learn, Game dan Review di mana setiap menu mengandungi pembelajaran yang berbeza kandungan. Reka bentuk maklumat adalah berdasarkan Teori Kognitif, Teori Behaviorisme dan Teori Konstruktivisme. Model reka bentuk produk adalah berdasarkan Model Hannafin dan Peck (1988) terdiri daripada fasa Analisis, Reka Bentuk, Pembangunan dan Pengulangan dan Penilaian. Oleh itu, semua fasa akan mengandungi proses penilaian dan menyemak semula setiap fasa. Reka bentuk yang terlibat dalam pembangunan aplikasi JingoCat adalah informasi, interaksi dan antara muka. Metodologi kajian melibatkan temubual berstruktur untuk menilai kebolehfungsian aplikasi android yang dibangunkan. Penilaian terhadap pakar yang terdiri daripada empat orang pakar iaitu dua orang pakar dalam bidang Multimedia Kreatif dan dua orang pakar dalam bahasa asing (Bahasa Jepun). Hasil dapatan menunjukkan, keseluruhan pakar bersetuju bahawa reka bentuk informasi, interaksi dan antara muka memenuhi keperluan dan bersesuaian. Kesimpulannya, aplikasi pembelajaran abjad Jepun JingoCat menjadi satu Alat Bahan Bantu Mengajar (ABBM) dan mudah digunakan oleh semua pihak yang memerlukan

Hybrid micro-machining processes : a review

Micro-machining has attracted great attention as micro-components/products such as micro-displays, micro-sensors, micro-batteries, etc. are becoming established in all major areas of our daily life and can already been found across the broad spectrum of application areas especially in sectors such as automotive, aerospace, photonics, renewable energy and medical instruments. These micro-components/products are usually made of multi-materials (may include hard-to-machine materials) and possess complex shaped micro-structures but demand sub-micron machining accuracy. A number of micro-machining processes is therefore, needed to deliver such components/products. The paper reviews recent development of hybrid micro-machining processes which involve integration of various micro-machining processes with the purpose of improving machinability, geometrical accuracy, tool life, surface integrity, machining rate and reducing the process forces. Hybrid micro-machining processes are classified in two major categories namely, assisted and combined hybrid micro-machining techniques. The machining capability, advantages and disadvantages of the state-of-the-art hybrid micro-machining processes are characterized and assessed. Some case studies on integration of hybrid micro-machining with other micro-machining and assisted techniques are also introduced. Possible future efforts and developments in the field of hybrid micro-machining processes are also discussed

Machining Characteristics and Parametric Optimisation of Inconel 825 during Electric Discharge Machining

This paper presents the machining characteristics and parametric optimisation of Inconel 825 during die-sinking electrical discharge machining (EDM) process. This work considers seven input parameters out of which six are of three levels and one is of one level. Metal removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) have been considered as performance measures. Before carrying out physical experimental runs, the experiments have been designed using Taguchi’s L36 (21 × 36) orthogonal array (OA). In order to identify the significant input parameters, Analysis of Variance has been employed on the experimental data. Discharge current, pulse-on-time, tool material and tool electrode lift time are found as significant input parameters. The effects of these significant parameters on the performance measures have been presented using Taguchi\u27s technique. After machining, study of surface characteristics of the electric discharged machined surface has been carried out using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDXS) and X-ray diffraction (XRD). These studies help in obtaining the information pertaining to topography of the machined surface, material transfer from tool and dielectric to the machined surface, and presence of extra element and their different phases at the machined surface. It has been found from the research that Carbon, Oxygen, Iron, Nickel, Chromium and little amount of Molybdenum are transferred to the surface of work piece. Further, for the best yield of the process, the optimal combination of input parameters has been obtained and reported using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) as a multi-objective optimisation technique. Consideration of two different dielectric fluids and three different electrode materials is the novelty of the work

Surface Properties of SiCp/Al Composite by Powder-Mixed EDM

AbstractThis paper uses a kind of moderate volume fraction (40%) of SiC particle reinforced Al matrix composites (SiCp/Al) to research how the surface properties are affected in conventional EDM (EDM) and powder-mixed EDM (PMEDM). By means of environment scanning electron microscope (ESEM) and HIT friction and wear tester, surface micro-topography, elements and wear resistance were analyzed. Experiments and researches indicate that compared with EDM, the surface properties machined by using PMEDM are improved greatly. The PMEDM surface roughness decreases about 31.5%; corrosion resistance is better too; and wear resistance is twice of EDM. Powder-mixed EDM has promising applications in metal matrix composites machining field

Developments in the non-traditional machining of particle reinforced metal matrix composites

The non-traditional machining of particulate reinforced metal matrix composites is relatively new. However, researchers seem to pay more attention in this field recently as the traditional machining of particulate reinforced metal matrix composites is very complex. This research investigates different non-traditional machining, such as electro-discharge, laser beam, abrasive water jet, electro-chemical and electro-chemical discharge machining of this composite materials. The machining mechanism, material removal rate/machining speed and surface finish have been analysed for every machining process. This analysis clearly shows that vaporisation, melting, chemical dissolution and mechanical erosion are the main material removal mechanisms during non-traditional machining. The thermal degradation and the presence of reinforcement particles mainly damage the machined surface. The understanding of electro-discharge, laser beam and abrasive water jet machining is more developed than that of electro-chemical and electro-chemical discharge machining for particulate reinforced MMC