bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and FEM Study of Serrated Chip Formation in High Speed Turning Processes
Authors: Umer U. , Xie Li Jing , Askari Syed Jawid , Danish S.N. , Butt S.I.
Published: July 2011

The finite element method (FEM) has been used to model high speed turning processes with orthogonal cutting conditions. In most of the situations, continuous chip formation is used to analyze the turning process due to its stability and allowing many conditions to simplify the process. However with the increasing applications of high speed turning, serrated chip formation is becoming a more common phenomenon in metal cutting. Serrated chips usually occur in machining of difficult to cut materials at or above a threshold speed. An updated Lagrangian formulation has been used in this study which works with element deletion technique based on a failure criterion. The Johnson Cook strain-hardening thermal-softening material model is used to model serrated chip formation. In addition high speed turning experiments were conducted on AISI H13 tubes using PCBN to analyze serrated chip phenomenon. The chips were analyzed after surface treatment using scanning electron microscope. It has been found that the length of cuts in the chip increases with the cutting speed and the chip changes from serrated to discontinuous. Different process variables like cutting forces, chip morphology, stress, strain and temperature distributions are predicted at different process parameters using FEM. The results show cyclic variation in the cutting forces at high cutting speeds due to varying chip load.
Chemical Wet Etching of Silicon Wafers from a Mixture of Concentrated Acids
Authors: Ismail M.R. , Basirun Wan Jeffrey
Published: July 2011

Warpage on the backside of silicon wafer after thinning process is examined. The thinning process includes back-grinding (BG) and wet chemical etching (WCE). Results of wafer warpage were compared to sub-surface damage from Transmission Electron Microscopy (TEM) analysis and showed that sub-surface damage on the backside of the silicon 100 would induce high wafer warpage, and reduced wafer strength. Further studies from surface roughness and topography of each surface finish is obtained by Atomic Force Microscopy (AFM) and SEM show that low surface roughness is in accordance with smooth surface condition, which comes after the wet etching process.
Flank Wear Modeling in High Speed Hard Turning by Using Artificial Neural Network and Regression Analysis
Authors: Al Hazza Muataz H.F. , Adesta Erry Yulian Triblas
Published: July 2011

Predicting and modeling flank wear length in high speed hard turning by using ceramic cutting tools with negative rake angle was conducted using two different techniques. Regression model is developed by using design of expert 7.1.6 and neural network technique model was built by using matlab2009b. A set of experimental data for high speed hard turning of hardened AISI 4340 steel was obtained with different cutting speeds, feed rate and negative rake angle. Flank wear length was measured to train the neural network models and to develop mathematical model by using regression analysis. Predictive neural network models are found to be capable of better predictions tool flank wear within the range that they had been trained.
Machining Time Simulation in High Speed Hard Turning
Authors: Adesta Erry Yulian Triblas , Al Hazza Muataz H.F.
Published: July 2011

High speed hard turning is an advanced manufacturing technology that reduces the machining time because of two reasons; reducing the manufacturing steps and increasing the cutting speed. This new approach needs an economical justification; one of the main economical factors is the machining time. The machining time was breaking down into three main parts; productive time, non productive time, and preparation time. By using matlab Simulink, a new program was developed for machining time allowing the manufacturer to find rapidly the values of cutting time parameters and gives the management the opportunity to modify the processing parameters to achieve the optimum time by using the optimum cutting parameters. Table 1: Nomenclature d Depth of cut M T total machining time pmv t Total movement time D Work piece diameter h t handling time pch t Total Tool changing time f Feed rate tc t tool changing time pre t Total preparing time z e Engagement distance on Z-axis ch t Tool changing time per piece, prg t Programming time x e Degagement distance on X-axis am t Machine allowance time su t Set up time k Number of passes ao t Operator allowance time sum t Machine set up L Tool life a t Allowance time sut t Tool set up l Work piece length o t Tool movement at the rapid speed suw t Work piece set up N Spindle speed oA t From zero point to cutting point TH Tool hardness tool n No. of tool posts in the turret p t Total productive time o X tidy of the O t point o1 p Initial position of the turret. o Z = abciss of the O t point w Work piece weigh o2 p Position of the used tool c V Cutting speed c w Width of cutting speed r Rotation speed of the turret f V Feeding speed tool n no. of tool in the turret c t Cutting time o V Rapid speed speed r : Turret rotation speed
Effects of Process Parameters on Surface Finish in Cylindrical Grinding
Authors: Pal Pradip Kumar , Bandyopadhyay Asish , Rudrapati Ramesh
Published: July 2011

Cylindrical grinding is an efficient and useful method of achieving good dimensional accuracy and fine finish. Very often one of the main objectives of grinding process is to obtain very good surface finish. The present investigation takes into account the effects of common grinding parameters on surface finish obtained in cylindrical grinding. The material selected is mild steel. The grinding wheel dimensions and its specification are kept in-varied. Grinding parameters like in-feed, longitudinal feed and work speed have been varied at several levels. Surface finish parameter (Ra) has been measured and noted for evaluation of surface finish, by using the instrument Talysurf. These data have been analyzed, interpreted and discussed in the context of varied conditions of cylindrical traverse cut grinding. Apart from identifying relationships between process parameters and surface finish through graphical presentations, a number of techniques (Full Factorial Design, Response Surface Methodology (RSM) and MATLAB) have been applied on the experimental data to arrive at some conclusive remarks. The paper effectively shows how selection of process parameters may yield desirable surface finish.
Polishing Force Modification near the Boundary of a Part Surface
Authors: Tam H.Y. , Hua M. , Zhang Lei
Published: July 2011

This paper reports on an investigation of the relationship between the polishing force and the contact characteristics as the polishing tool approaches the boundary of a part surface during polishing. It was previous established that, for fixed abrasives, when the polishing tool is on the inner surface, the relationship between the polishing force and the pressure at the contact is approximately Hertzian and the contact is a full ellipse. The contact cannot be a full ellipse as the tool touches the boundary. The same polishing force could yield rather different pressure distribution, and thus rate of material removal, within the contact region. A model is proposed to relate the force and the pressure distribution as the tool is close to the edge of a part surface. The model takes into account changes of the contact near the edge. Experimental results are also presented to validate the proposed method.
Influence of Electrode Cooling on Recast Layers and Micro Crack in EDM of Titanium
Authors: Abdulkareem Suleiman , Khan Ahsan Ali , Konneh Mohamed
Published: July 2011

Electrical discharge machining (EDM) process is a manufacturing method for shaping hard metals and formation of deep and complex shaped hole by spark erosion in electrical conductive materials such as metals, metallic alloys, ceramics etc. EDM process is achieved by a series of recurring electrical discharges between the electrode and workpiece in the presence of dielectric fluid. EDM unique feature of using thermal energy to machine conductive materials irrespective of material hardness has been its major advantage in the manufacture of aerospace, surgical, mould, die, automotive and as well as sport components. The effectiveness of EDM process depends among other factors on the thermal properties of the electrode material. The objective of this study is to study the influence of electrode cooling on recast layers and micro crack in EDM of titanium. The machining parameters investigated in the present study are current intensity (I), pulse on-time (Ton), pulse off-time (Toff) and gap voltage (V), which are of great interest for EDM researchers. The copper electrode is used to EDM titanium workpiece at room temperature and at sub-zero temperature using liquid nitrogen. The influence of cooling of copper electrode on recast layers and micro crack on titanium were investigated using scanning electron microscope (SEM) and has been reported in this study.
Investigation of Microholes Produced by Focused Ion Beam Micromachining
Authors: Hajar Nurul , Ali Mohammad Yeakub
Published: July 2011

This paper discusses the microfabrication of microholes using focused ion beam and investigation of geometrical integrity of microholes. Different combination of aperture size, probe current, acceleration voltage was applied for micromachining and optimized based on taper angle. Microholes with 3.0 μm of diameter were milled according to the optimized parameter using bitmap mode. The depth range of microholes was 1.0-5.5 μm. The hole’s depth and taper angle were investigated for characterization. Each of the microholes was cross sectioned for investigation. A relationship of taper angle (θ), depth and aspect ratio were plotted. Low aspect ratio (less than 1) would give the lower taper angle and hence better integrity. Acceleration voltage of 25 kV, probe current of 41.5 pA and aperture size of 4 nm produced lower taper angle for different aspect ratio.
Two Dimensional Quasi-Steady Molecular Statics Nanocutting Simulation for Cutting Copper Material with Point Defect
Authors: Lin Zone Ching , Ye Jia Rong
Published: July 2011

This article presents a quasi-steady molecular statics nanocutting simulation model for simulating orthogonal two dimension cutting copper materials with different point defects by using diamond cutters. The analyses of cutting action, cutting force, equivalent strain and equivalent stress are taken during nanocutting copper material with point defect. The two dimensional quasisteady molecular statics nanocutting model first assumes the trajectory of each atom of copper workpiece being cut whenever the diamond cutter goes forward one step. It then uses the Hooke- Jeeves search method to solve the force equilibrium equation of the Morse force in X and Y directions when each copper atom moves a small distance, so as to find the new movement position of each copper atom. Then, the displacement of the acquired new position of each atom combined with the concept of shape function of finite element method are employed to calculate the equivalent strain of the copper workpiece during nanocutting . By using the relationship equation of the flow stress-strain curve, the equivalent stress of the copper workpiece during cutting can also be calculated
Mechanochemical Reduction of MoO3 Powder by Silicone to Synthesize Nanocrystalline MoSi2
Authors: Ramezanalizadeh H. , Heshmati-Manesh Saeed
Published: July 2011

Molybdenum disiliside is known as a ceramic material with attractive properties for high temperature structural applications. In this study, mechanical alloying was used to produce MoSi2 powder directly from molybdenum oxide. Mixture of MoO3 and Si powders with commercial purity were exposed to high mechanical activation in a planetary ball mill. The ball to powder mass ratio was selected to be constant at 33:1 and the rotation speed (cup speed) was 600 rpm during the milling operations. Crystallite sizes and structural evolutions during milling were investigated by Xray diffraction analysis. The morphology of the mechanically alloyed powders was evaluated with scanning electron microscope (SEM). From XRD results, it was observed that within 6 hours of milling MoO3 was reduced and fully converted to MoO2. After 17 hours of milling MoO2 also began to reduce and peaks of MoSi2 (both and phases) and Mo were detected. Further milling resulted in a gradual decrease in MoO2 peak intensities because of its continuous reduction. Peaks of MoO2 were also broadened due to refinement of MoO2 crystallite sizes. Scherrer and Williamson-Hall methods using XRD patterns were employed to calculate the mean crystallite size. Calculations indicated that in the sample ball milled for 50 hours, MoSi2 crystallite sizes were less than 100 nm.
Influence of Magnetic Field on Corrosion Resistance and Microstructure of Electrodeposited Ni Coatings
Authors: Ebadi Mehdi , Basirun Wan Jeffrey , Alias Yatimah
Published: July 2011

This paper focuses on the electrodeposition of nickel from a Ni Watts solution in the presence and absence of a permanent parallel magnetic field (PPMF) to the cathode surface. It was found that the difference between the mass deposition were enhanced in the presence of PPMF and absence of a PPMF (B = 4.4 T) with increase of current density ( m= 0.413 to 4.173 mg cm2 in 6 min). The thickness of deposited layers with PPMF was smaller than without PPMF, therefore higher density of electrodeposited layers can be brought upon by the application of PPMF. The corrosion behavior of samples was tested in the presence and absence of a PPMF (9T). The Polarization resistance was reduced in the presence of the PPMF. The deposited layers were characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Atomic force Microscopy (AFM).
Analysis of Microstructural Changes during Pulsed CO2 Laser Surface Processing of AISI 316L Stainless Steel
Authors: Chikarakara Evans , Naher Sumsun , Brabazon Dermot
Published: July 2011

In the present contribution, a 1.5kW CO2 laser in pulsed wave mode was used to study the effects of laser processing parameters at specific energy fluence. Cylindrical AISI 316L stainless steel samples rotating perpendicular to the laser irradiation direction were used for these experiments. A surface temperature prediction model was implemented to set the experimental process parameters. Laser processing of AISI 316L steel showed a strong correlation between melt pool depth and the residence time at specific fluence levels. At fixed energy fluence, increase in residence time resulted in growth of the melt pool depth. In the melted region, the microstructure was observed to be of more uniform composition and contain fewer impurities. To improve absorption level, samples were etched and roughened. These samples exhibited lower roughness levels compared to the un-treated samples. For a constant fluence level, samples with improved absorption displayed an increase in depth of melt pool at lower peak powers and higher residence time. As the laser beam interaction time increased, the surface roughness of the steel increased for the various pulse energy levels examined. While the structure of the surface was seen to retain a crystal arrangement, grain orientation changes were observed in the laser processed region.
Effects of Processing Parameters on Microstructures and Properties of TIG Melted Surface Layer of Steel
Authors: Mridha S. , Dyuti S.
Published: July 2011

In order to modify surface structure titanium powder was preplaced on steel surface and melted under TIG (tungsten inert gas) torch in a pure nitrogen environment which formed a resolidified layer of around 1 mm thickness. The preplaced titanium powder content was varied between 1.3 and 1.8 mg/mm2 and melting was conducted with energy inputs of 324 J/mm to 540 J/mm. The modified surface layer was analyzed in terms of microstructure, hardness, surface defects such as cracks and pores. The resolidified layer consisted of dispersion of TiN, Ti2N and TiN.88 dendrites in a ferrite matrix containing titanium. The modified layer showed some defects when melting were performed with low energy inputs. A maximum surface hardness of around 2000 Hv was developed in most of the tracks and this hardness corresponds to high concentration of TiN dendrites within the modified layer.
Wear Behavior of Modified Surface Layer Produced by TIG Melting of Preplaced Ti Powder in Nitrogen Environment
Authors: Dyuti S. , Mridha S. , Shaha S.K.
Published: July 2011

The formation of hard surface layer on steel provides a protective coating against wear, thermal loads and corrosion. In the present work a hard composite layer is formed on steel surfaces by preplacement of titanium powder and melted under nitrogen environment. Surface melting was conducted using TIG torch with different energy inputs. The microstructure and the morphology of the melt tracks were investigated using SEM and X-ray diffraction. The in-situ melting of titanium powder in nitrogen atmosphere produced dendritic microstructure of titanium nitride. The melt layer contained dispersed TiN, Ti2N dendrites highly populated at the surface compared to the deeper melt and gave a maximum surface hardness of around 1927 Hv. The wear property of the melt track was investigated using pin-on-disk tribometer at room temperature. The modified surface layer gave a low friction value of 0.12 and wear rate of 0.007895 ×10-4 compared to 1.648 × 10-4 mm3/N/m for the uncoated steel surface.
Coating Produced by Deposition of Nanoparticles Blended Wires
Authors: Al Askandarani A. , Hashmi M.S.J. , Yilbas Bekir Sami
Published: July 2011

Gas shield electric arc coating of carbon steel surface is considered in relation to repair applications. Two types of wires are incorporated in the experiments including standard and nano-particle blended. The coating structure and the metallurgy are examined using the Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). The microhardness of the resulting coating is measured and compared with the results obtained from the conventional wire. It is found that fine structures are formed in the coating due to the presence of nanoparticles. In this case, microhardness increases significantly in the coating.
TiO2 Foam: Characterization and Cell Adhesion
Authors: Hazan Roshasnorlyza , Sreekantan Srimala , Khalil Adilah Abdul , Nordin Ira Maya Sophia , Mat Ishak
Published: July 2011

In recent years, it has been proposed that the new era of implants design should be focused on the use of the new generation of biocompatible materials or reengineers the currently available materials. The objective of this research was to study cell-metal interactions using highly porous TiO2 foam. To obtain the porous TiO2 foam, polymeric foam replication methods might be one of the most effective methods. Surface chemical composition, morphology and phase are investigated by field emission scanning electron microscope (FESEM) and X-Ray Diffraction (XRD). In vitro cellular response of cells has been studied on TiO2 foam. In the investigations of the cellular responses of cells, two aspects were considered: the number of growing cells and their morphological features. It was clear that rough surface morphology was important factor for better cell-metal interaction. Surface topography can affect the cell migratory significantly and adhesion behavior on implant surfaces.
3D Modelling and Analysis Flow of Air Conditioner Outdoor Fan for Cost Reduction
Authors: Choi Seung Hyun , Kim Jae Yeol
Published: July 2011

Spread of household air conditioning system is continued to be increased. Along with the spread, the acknowledgement on product quality by the customer is increasing. Therefore, not only basic performances like cooling and power consumption but also design and noise level of in-house and external unit become the important factors. Axial fan in the external unit of air conditioning system is for ventilation and air supplying unit, and the related products have been widely adopted as household electronics, automobile engine, big sized blower in factory, tunnel, and subway. In this study, commercial 3-winged propeller fan from S company is modified to 2-winged fan for the cost reduction. Using 3D modelling, the fan shape is modified, and analysis flow is adopted to provide the way to reduce cost while maintaining the same wind capacity.
Effect of Draw Bead Height on Wall Features in Rectangular Deep-Drawing Process Using Finite Element Method
Authors: Thipprakmas Sutasn
Published: July 2011

Concave/convex wall features are usually generated in the deep-drawn parts with complicated geometry, especially the difficult-to-deep draw materials. The application of the draw bead could reduce the concave/convex wall features. However, it is difficult to determine the suitable draw bead geometry and its position to obtain a straight wall. In this study, the effects of draw bead height were investigated using the finite element method (FEM) and experiments. The application of the draw bead and the effects of its height on the concave/convex wall features could be theoretically clarified on the basis of principal stress distribution. The application of draw bead led to the decrease in tensile stress in the direction of punch movement and also increased in the tensile stress distributed to the corner zone; therefore, the concave wall feature decreased. In addition, this feature decreased as the draw bead height increased. However, the application of a very large draw bead height resulted in a convex feature. The FEM simulation results were validated by experiments in the following two cases, i.e., without and with draw bead formations. With reference to the material thickness distribution, the FEM simulation results showed a good agreement with experimental results.
Effect of Moulding Sand Properties on Cost Effective Hybrid Rapid Casting Solution for Zinc Alloy
Authors: Singh Rupinder , Lal T.
Published: July 2011

The purpose of the present experimental investigations is to study the effect of moulding sand properties on reducing the shell wall thickness of mould cavity for cost effective, hybrid rapid casting solution of zinc alloy. Starting from the identification of component/benchmark, technological prototypes were produced, with three different moulding sands (dry, green and molasses), at different shell wall thickness of mould cavity using hybrid rapid prototyping technique (combination of three dimensional printing and conventional sand casting). Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the castings produced. Some important mechanical properties were also compared to verify the suitability of the castings. The study suggested that for the shell thickness, having value less than the recommended one is more suitable from dimensional accuracy and economic point of view, for all three moulding sands. Further best shell wall thickness of the mould cavity for different moulding sands, for the selected component/benchmark has been highlighted for rapid casting solution of zinc alloy.
Conceptual Design of Aluminium Metal Matrix Composite Brake Rotor System
Authors: Maleque M.A. , Rahman M.M. , Hossain M.S.
Published: July 2011

Composite materials have become a popular material substitution for automotive, sports, medical, aerospace and other engineering fields due to their light-weight, high strength and/or stiffness of fibres. In this paper, a conceptual design approach has been presented to develop aluminium metal matrix composite (AMC) automotive brake rotor system. A systematic and stepby- step approach of full design is shown for better understanding of the design concept of automotive brake rotor. The methodology of conceptual stage, computer aided design (CAD) and evaluation systems are discussed for illustrating and selecting the best concept. A total of six (6) concepts for both surface rejuvenates feature and ventilated cooling fins are explained. It was found that the Concept 6 for surface rejuvenates feature and Concept 1 for ventilated cooling fins are the best combination for aluminium metal matrix composite brake rotor application.
An Elasto-Plastic Finite Element Analysis of the Radial Compression of Aluminium Tube between Rigid Plates
Authors: Chen Tsung Chia
Published: July 2011

This study aims to clarify the process conditions of the radial compression of aluminum tube. It provides a model that predicts not only the correct punch load for compression, but also the precise final shape of products after unloading, based on the compression properties of the material and the geometry of the tools used. An elasto-plastic incremental finite-element computer code, based on an updated Lagrangian formulation, was developed to simulate the radial compression of aluminum tube. In particular, selective reduced integration was adopted to formulate the stiffness matrix. The extended r-minimum technique was used to deal with the elasto-plastic state and contact problems at the tool-metal interface. A series of simulations were performed to validate the formulation in the theory, leading to the development of the computer codes. The whole deformation history and the distribution of stress and strain during the forming process were obtained by carefully considering the moving boundary condition in the finite-element method. Results in this study clearly demonstrated that the computer code for simulating the radial compression of aluminum tube was efficient.
Speciation of Mercury in Environmental Water Samples with Seasonal Change
Authors: Rahman M.M. , Mohd Yusof Alias
Published: July 2011

Mercury concentrations and speciation were determined in surface water samples taken from rivers in the vicinity of industrial area, in Johore Malaysia. Samples were collected from the same sites before and immediately after rainfall. The aim of this study is to assess the influence of seasonal change in river water on the concentration of mercury (Hg) species. Trace concentrations of mercury in water samples were determined by a method involving a simple and rapid procedure involving the flow-injection inductively coupled plasma mass spectrometry (FI-ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS) techniques. Mercury vapor, generated by sodium borohydride as the reductant, was stabilized by potassium dichromate (K2Cr2O7), then released by controlled heating and detected by FI-ICP-MS. Methyl mercury (II) was preconcentrated using the ammonium pyrolidindithiocarbamate (APDTC)-chloroform extraction procedure and the chloroform extract was introduced into the graphite tube. The absolute detection limits were found to be 0.204 μg L-1 and 0.273 μg L-1 for total mercury and methyl mercury respectively, with thevariability being lower than 5% relative standard deviation (RSD) at the 5 μg L-1 level. Because of the high stability of MeHg (II)-APDTC complexes, it is possible to evaporate the extract in order to obtain a crystalline powder to be dissolved with a few micro liters of chloroform enacting MeHg (II) and Hg (II) can be detected at sub-nanogram levels.
Finite Element Method for Predicting the Cohesive Strength of DLC Film on 316L Stainless Steel by Four Point Bend Test and Validation with Experimental Results
Authors: Morshed Muhammad M. , Daniels Stephen M. , Hashmi M.S.J.
Published: July 2011

The mechanical performance of DLC coatings on 316L stainless steel deposited by a saddle field fast atom beam source has been evaluated using the four point bend (FPB) test. Two different deposition parameters, pressure and current were varied when depositing the films. Load-displacement measurements were carried out during the bend test to determine the load corresponding to crack initiation. This load designated as the cohesive strength of the coating which is also called the cracking resistance of coating and provides a measure of the strength of the coating. The cohesive strength of the coating was calculated based on elementary beam theory. Scanning Electron Microscopy (SEM) was used to determine the location of the crack. Finite element analysis was used to predict the stress distribution across the coating thickness. The experimental work on FPB tests has been used to support the numerical (finite element) model for the determination and prediction of film cohesive strength. It was observed that at lower deposition current, the cohesive strength increases with increased deposition pressure whereas, for higher deposition current, these values do not increase with increasing deposition pressure. The model takes into account the film’s Young’s modulus, thickness and deposition pressure and current, and has shown that it is capable of predicting film cohesive strength when combined with a theoretical formulation for brittle fracture. It has been observed that the maximum stress develops at the outer surface of the film and propagates through the film-substrate interface. This result has only been validated for films with higher Young’s modulus compared to that of the substrate material.
Synthesis of High Fracture Toughness of Hydroxyapatite Bioceramics
Authors: Tan Chou Yong , Singh Ramesh , Tolouei R. , Sopyan Iis , Teng Wan Dung
Published: July 2011

The sinterability of magnesium oxide (MgO) doped hydroxyapatite (HA) ranging from 1 to 10 wt% when sintered at 1150°C was investigated in terms of phase stability, bulk density, Young’s modulus, Vickers hardness and fracture toughness. The addition of up to 1 wt% MgO as sintering additive was found to be beneficial in promoting the densification of HA. Further addition of MgO in the HA matrix would deteriorate its densification properties. Similar results were observed for its stiffness and Vickers hardness. Nevertheless, the fracture toughness of HA was greatly enhanced by the incorporation of 5 wt% MgO. An increased toughness of up to 35% was obtained for the MgO-doped HA when compared to the undoped HA. This improvement is associated to the smaller grain size of the doped sample as compared to the undoped HA.
Characterization of Globular Microstructure in NMS Processed Aluminum A356 Alloy: The Role of Casting Size
Authors: Akhlaghi Farshad , Farhood Amir H.S.
Published: July 2011

Semi-solid processing (SSP) technology, due to its ability to provide near-net-shape components with properties far exceeding those of other casting technologies is considered as an alternative for forgings and investment castings. Conventional semi-solid forming, involving the use of heated billets, melt stirring or using cooling slopes require many processing steps and supplementary equipments. This article describes Narrow Melt Stream (NMS), as an alternative process for semi-solid processing of aluminum alloys that eliminates capital cost expenditures, reduces the number of steps required, and hence reduces the costs of making components with a globular structure. However, the applicability of this technique in producing globular structures in the large molds has not been explored. In the present study the results of a systematic investigation on the effects of mold size on the size and morphology of the globular structures formed by NMS processing of Al 356 alloy is reported. For this purpose, five different series of molds were employed. Each series consisted of three molds with identical volumes but different casting moduluses. By using these molds, the effects of casting modulus at constant casting size as well as the effect of casting volume on the size and shape factor of the globular structures in aluminum A356 samples prepared by NMS technique is reported.
Casting of Net Inserted Aluminum Alloy Composite Strip
Authors: Nakamura Ryoji , Haga Toshio , Takahashi Kenta , Kumai Shinji , Watari Hisaki
Published: July 2011

The net-inserted metal matrix composite strip could be cast by a twin roll caster at only one process. The net could be inserted in the strip or lower surface of the aluminium alloy strip. The matrix was Al-12mass%Si, and inserted net was made from SUS304 stainless steel. The diameter of the wire of the net was 0.29mm, and distance between the wires was 0.98mm (#20). The roll speed was 30m/min. The net was not reacted with the matrix, and there was not gap between the matrix and the net. The mechanical property of the net-inserted composite strip was affected by the direction of the wire of the net. When the angle of the wire against the tensile direction was 45 degrees, elongation of the composite became better than that of the matrix from 14% up to 23%. This reason was improvement of the local contraction of the composite strip. The net-inserted composite strip could be cold rolled. The reduction of the net was smaller than that of the strip. The reduction of the wire at rolling direction was larger than that of the wire at lateral direction.
Roll Casting of Al-40%Sn-1%Cu Alloy Strip
Authors: Nakamura Ryoji , Haga Toshio , Kumai Shinji , Watari Hisaki
Published: July 2011

In this study, the roll casting of Al-40%Sn-1%Cu alloy was tried by an unequal diameter twin roll caster. The unequal diameter twin roll caster could continuously cast the strip. The casting load of the roll was small to prevent the flow out of the Sn. The roll-load was 0.1kN/mm(unit width). The roll casting of 400mm-width strip of 8mm-thick was tried, and it was attained. The gravity segregation of Sn did not occur. The as-cast strip could be cold rolled down to 1mm. However, this strip had much porosity. The rapid solidification was useful to prevent the porosity. The copper roll was better than steel roll to increase cooling ability. The copper roll was suitable to prevent the porosity. The temperature of solidified metal was important factor which influenced the porosity. The 4mm-thickness strip with little porosity was could be cast at the speed of 30m/min.
Al-4.5 Cu-3.8 Fe In Situ Composites: Effect of Rolling on Microstructure and Wear Properties
Authors: Shaha S.K. , Kurny A.S.W. , Hasan Mahbub , Dyuti S.
Published: July 2011

Al based MMCs have attracted a lot of attention particularly for their desirable combination of high stiffness and low specific gravity. In the present study, Al-4.5Cu-3.8Fe in-situ composites were manufactured by using solidification process. During solidification Al-Fe intermetallic was formed in a matrix of Al-Cu alloy. The composite was hot rolled at different degree using a two high rolling mill. Subsequently the composites were characterized by SEM, XRD, hardness measurement and wear testing. Wear testing was conducted on a pin-on-disk machine by applying 10 KN load. After the wear tests, the worn surfaces of the composite specimens were examined under an optical microscope. According to experimental results, as cast in-situ composites exhibited the highest wear rate. The hardness increased and wear rate decreased with the extent of rolling. The presence of reinforcing Al3Fe phase and fragmentation of those particles during hot rolling are suggested to contribute to the better wear resistance of the composites. The extent of abrasive wear was largest in the case of as cast composites, as evidenced by deep grooves on the worn surface and highest weight loss.
Effects of Testing Temperature and Sliding Speed on the Wear Behavior of a Low Alloy Gas Nitrided Steel
Authors: Emami Mohammad , Ghasemi H.M. , Rassizadehghani J.
Published: July 2011

Effects of wear testing temperature and sliding speed on the wear behavior of nitrided and untreated 31CrV3 steel were investigated. The specimens were tested at wear testing temperatures of 25°C and 500°C under a normal load of 15N at a sliding speed of 1m/s. The increase in the wear temperature from 25°C to 500°C led to a decrease in the wear rate and coefficient of friction of the nitrided steel samples. At 25°C, the wear resistance of the nitrided steel improved by 2.3 times compared to the untreated specimen. There was about 57 times improvement in wear resistance as the wear temperature increased to 500oC for the nitrided specimen. Scanning electron micrographs showed that the formation of compact and protective oxide layers on the worn surface of the nitrided steel was responsible for the improvement in the tribological behavior of nitrided steel at elevated temperatures. The effect of sliding speed on the wear of the samples was further tested at 500oC under a normal load of 15N at sliding speeds of 0.5 and 1.5m/s. The results showed that there was higher wear resistance at lower sliding speeds.
Effect of Addendum Parameters to the Formability of Aluminum AL 6303
Authors: Afzeri  , Shahdan M.S. , Qasim H. Shah
Published: July 2011

Procedure of die design is mostly based on iterative try and error to obtain final design with good stamping formability. The stamping formability of sheet metal part is possible to be improved by adding addendum features at die model. In this paper discusses the effect of drawbars toward the formability of stamping process of aluminum AL6063. Effect of addendum size is evaluated Finite Element Simulation to prevent wrinkling and tearing. Simulation model is constructed by designing a simple die, punch and binder using variety drawbar diameters. The model further evaluated using LS-Dyna software interfaced by forming tool of LS-Prepost. Formability of the model is evaluated through yield stress, major strain and minor strain data. From the result of evaluation obtained that without draw beat, major/minor strain is above FLD while the formability is improved by applying 5 mm draw bead diameter.
Research on Multi-Steps Tube-Compression of Thin-Wall Parts with Variable Diameter by Viscous Pressure Forming
Authors: Wang Zhong Jin , Li Ji Guang , Gong Hai Lan
Published: July 2011

Tube-compression is one of the usual forming methods for variable diameter parts. Due to the influence of compression instability, buckling and wrinkling are prone to occur in tube-compression process, especially for the thin-wall parts, which restricts the diameter reduction ratio limit. In this paper, the viscous pressure forming (VPF) method is proposed for the problems in tube-compression. Utilizing the mechanical property and easily achieved loading mode of viscous medium, the buckling in the tube-compression process can be delayed and wrinkles caused by buckling can be eliminated, so as to increase the diameter reduction ratio limit. The multi-steps forming can divide the large total deformation into much small deformation, thus the small deformation can be controlled in the range of buckling and wrinkling. The process has the more ability to improve material’s forming capability than one-step forming. The deformation of the multi-steps tube-compression process by VPF is analyzed by finite element method (FEM). The variation of length-to-diameter and wall thickness after each step forming has influence on the next step compression. This forming method can also be used in tube-compression of high strength materials and can realize precise plastic forming of parts with high strength, thin-wall and large diameter variation ratio.
Formation of Globular Microstructure in A380 Aluminum Alloy by Cooling Slope Casting
Authors: Saklakoğlu Nurşen , Gencalp S. , Kasman Şefika , Saklakoğlu İ.E.
Published: July 2011

Thixoforming and related semi-solid processing (SSP) methods require thixotropic materials. One of the many SSP techniques is the cooling slope (CS) casting process, which is simple and has minimal equipment requirements, and which is able to produce feedstock materials for semisolid processing. When the feedstock is reheated to the semisolid temperature range, non-dendritic, spheroidal solid particles in a liquid matrix suitable for thixoforming are obtained. In this study, equipment for the CS technique was first established, and then the effects of the pouring temperature and inclined slope angle on the microstructures of A380 aluminum alloy (ISOAlSi8Cu3Fe) were studied. Optimum parameters for thixoforming experiments were selected, and it was found that the microstructure produced by the inclined plate depended on its angle and the pouring temperature.
Aluminium Metal Matrix Composite: Improving Wear Performance through Treatment
Authors: Maleque M.A. , Karim M.R. , Yassin N.
Published: July 2011

The main objectives of the present study are to develop/manufacture SiC reinforced aluminium matrix composite (SiCp/AMC) with different reinforcement combinations using stir casting method and investigate the effects of heat treatment on wear performance. AMCs were prepared using 20 vol% SiC with three different reinforcement combinations into aluminum matrix. Stir casting is a primary process of composite production whereby the reinforcement ingredient material is incorporated into the molten metal by stirring. The reinforcement combination consists of 20% (single particle size), 7% and 13% (double particle size) and 5%, 5% and 10% (triple particle size). The triple particle size (TPS) composite consist of SiC of three different sizes viz., coarse, intermediate and fine. The solution heat treatment was carried out on cast specimens at 540 0C for four hours followed by precipitation treatment. The wear test was carried out using a pin-ondisc type tribo-test machine under dry sliding condition. The wear morphology of the damaged surface was also studied using optical microscope and scanning electron microscope (SEM) in this investigation.
Quantitative Stereology for Roughness Morphology of Aluminum Alloy
Authors: Salehudin N.E. , Jalar Azman , Daud Abdul Razak
Published: July 2011

Average roughness is an increasingly important method in material sciences. The searching for a possible correlation between average roughness and impact energy are current interest. This paper present the results of an experimentally study made on the correlation between the average roughness and the impact energy in aluminum alloy by using scatted diagram. The impact energy of aluminum alloy was obtained by using Charpy Impact Test. The micrographs of fractured aluminum alloy were analyzed with the IFM (Infinite Focus Measurement) profile to determine the parameter of average roughness. The result shows the relationship maybe established between average roughness and impact energy.
An Investigation of Mechanical Non-Sinusoidal Oscillation of Continuous Casting Mold
Authors: Zhang Xing Zhong , Zhu Hong Tao , Tieu A. Kiet , Xie Hai Bo , Du Xiao Zhong , Li Xian Kui , Dou Chun Xia
Published: July 2011

In this paper, a new technique to set up non-sinusoidal oscillations of the mold in continuous casting is presented. The waveform functions of this non-sinusoidal oscillation technique and operational parameters are analyzed and the design to realize the non-sinusoidal oscillation of mold is presented. It is anticipated that this technique will be widely applied as it has many advantages such as lower investment and maintenance cost, simple equipment which is easy to manufacture and maintain.
Simulation and Fabrication of Automobile Parts in Semi-Solid Process
Authors: Kim H.H. , Kang Chung Gil
Published: July 2011

Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.
A Study on Magnetostrictive Sensor for Detecting the Weld Defects
Authors: Seo J.H. , Kim Il Soo , Kang B.Y. , Shim J.Y. , Jeong J.W. , Kim J. S.
Published: July 2011

Industries such as gas, oil, petrochemical, chemical, and electric power have generally employed for the operation and used to enlarge the equipment or structures that require a high capital investment. In order to meet these requirements, the industries are increasingly moved toward saving the experimental verifications and computer simulation. Therefore industries to reduce the maintenance costs without compromising operational safety have been forced on finding better and more efficient methods to inspect their equipment and structures. It was motivated to meet the industrial needs and to secure and maintain the institute's technical initiative and leadership in the development of this new and exciting technology. Also, the system with many sensors could be detected the weld defects, and was useful for real-time monitoring. This paper is focused on the development of the real-time non-contract monitoring system as an efficient tool for the experimental study of weld defects based on the relationship between the measured voltage and input parameters. The monitoring technology involves the use of Ms S (Magnetostrictive Sensors) for the generation and detection of the guided waves. The developed system was employed to the experimental study in order to fine the weld defects for steel object with artificial defects used in the welding field.
The Effect of Heat Treatment Parameters on Microstructure and Toughness of Austempered Ductile Iron (ADI)
Authors: Abedi Amir , Marashi S.P.H. , Sohrabi K. , Marvastian M. , Mirbagheri S.M.H.
Published: July 2011

In this investigation, the effect of heat treatment parameters on the microstructure and impact energy as a measure of toughness of the austempered ductile cast iron (ADI) was studied. Yblocks were casted from ductile cast iron with following composition: 3.2% C, 2.5% Si, 1.09% Ni, 0.87% Cu, 0.5% Mo and 0.16%Mn. Charpy specimens (un-notched) were machined from the straight part of Y-blocks. All of specimens were heat treated with different conditions. Some of them were austenitized at 900°C for 60 min and then austempered at 250, 300, 350 and 400°C for various durations. Then, hardness test, impact test, optical microscopy and X-ray diffraction (XRD) were performed on the heat treated ductile iron samples. The results reveal the highest impact energy (105 J) for the sample austenitized at 900°C and austempered at 350°C for 150 min. The microstructure of this sample consisted of 28% austenite and broad ferrite needles.
Research on Crack Healing in Slab during Hot Rolling
Authors: Yu Hai Liang , Liu Xiang Hua
Published: July 2011

The elongation and the strength of rolled steel are severely affected by cracks in production. Reduction of cracks is important for the improvement of slab quality. In this paper, a series of experiments on internal crack healing in slab during rolling was carried out on the experimental rolling mill. The crack shape and the fracture morphology of the crack healing zones were observed by using the scanning electron microscope, and the shear strength of crack healing zone was tested through the tensile testing machine. With increase of the reduction ratio during rolling, the crack healing degree increases.