Applied Mechanics and Materials Vols. 799-800

Abstract: This paper investigates optimized design of Electro Discharge Machining process parameters on HCHCr i.e. DIN 17350-1.2080 Die steel. This process is one of the most widely applied non-traditional machining processes. To determine the optimal EDM conditions in several industrial fields. Taguchi method has been utilized to optimize only a single performance characteristic. To overcome this limitation, the Grey Relational Analysis theory has been used to determine grey relational grade as performance index to determine the optimal combination of the parameters such as peak current (I), pulse duration (Ton), voltage (V) to evaluate multiple performance characteristic such as metal removal rate and surface roughness simultaneously. Moreover, the Principal Component Analysis is applied to evaluate the weighting values corresponding to metal removal rate and surface roughness performance characteristics so that their relative importance can be properly defined. The analysis reveal that Grey Relational Analysis coupled with Principal Component Analysis can effectively be used to obtain the optimal combination of EDM process parameters. The obtained optimal machining conditions were Peak current at 15A, pulse on time at 250μs, Voltage at 85V. It is also observed that magnetic field in spark zone have improved metal removed rate and surface finish.

Abstract: In drilling and boring process, the relief in clamping stress causes deformations that cause variations in the geometry of the drilled hole. In automobile industry, when such holes are used to hold gear systems or rods in place, this variation in geometry leads to poor fitting and subsequent failure. To avoid this, high level accuracy is required which is both expensive and time-consuming. Therefore, a high percentage of such drilled parts are rejected in industry. The present paper addresses this problem by characterizing the variations in hole geometry as a function of clamping force, hole diameter, hole eccentricity (distance of hole-center from center of drilled face) and angular position of hole with respect to clamp location. The analysis result quantifies the comparative effect of each aforementioned factor on hole geometry variation. Taguchi Method based Design of Experiments using L25 orthogonal array has been used for performing the parametric design to arrive at the best settings of the 4 parameters. The optimal settings minimize ovality and displacement of the hole-center, and thus increase hole-fitting and its reliability against manufacturing variability.

Abstract: A new configuration of chromizing process was developed by separating Cr powder from NH₄Cl. FC220 gray cast iron specimens were chromized in this new experimental setup at 450, 550, 650,750, 850 and 950°C during 13 hours in order to study the possibility of chromizing at “low” temperature. The chromized specimens were examined using Scanning Electron Microscopy (SEM), macro-hardness, micro-hardness, compression test and salt spray test. The results shows that the specimen chromized at 650°C gives the best compromise between the corrosion resistance and the hardness of the FC220 with 1.73 ڌm of thickness of the chromized layer. However, after 13 hours of the process, the hardness of the FC220 specimens decreased considerably from 93 HRB to 64.2 HRB (31%).

Abstract: Roll to roll process is one of the famous printing techniques that are possible to create graphic and electronic device on variable substrate by using conductive ink. Graphene is an example of material that can be used as printing ink which usually used in producing micro-scale electronic devices. Here, it is proposed that extending roll to roll printing technique into the multiple micro-scale printing fine solid line onto substrate by using graphene as a printing ink. Flexography is a high speed roll to roll printing technique commonly used in paper printing industry. And this study elaborates the feasibility of graphene as a printing ink use in combination of flexography and micro-contact or micro-flexo printing for micro fine solid line. This paper will illustrates the review of graphene in producing multiple micro-solid lines printing capability for the application of printing electronic, graphic and bio-medical.

Abstract: The accuracy and clogging of microchannels are important for assessing the quality of lab on chip (L-O-C) devices. The clogging affects the fluid mixing efficiency and influences the bonding of substrate. In this paper, inexpensive and quick method for microchannel fabrication in polymethyl methacrylate (PMMA) while reducing the thermal damage is introduced. Accordingly, the substrate was covered with a thin layer of water during CO₂ laser ablation. The effect of water cooling on the clogging formation, heat affected zone and the microchannel geometry in terms of depth and width is investigated. Clogging formation mechanism in the intersection of Y-channel is studied to improve its quality for microfluidics applications. During the experimental work, the CO₂ laser power was varied from 2.4 to 6 W at scanning speed from 5 to 12.5 mm/s. The results showed that covering the PMMA substrate with a thin layer of water prevented clogging formation and reduced the heat affected zone.

Abstract: The tensile test operating in a SEM chamber was applied to investigate the adhesion behaviour of the oxide scale on AISI 441 stainless steel used as interconnect in solid oxide fuel cells (SOFCs). The samples were prepared by aligning the final polishing directions parallel and perpendicular to the tensile loading. The samples were oxidised in water vapour and synthetic air at 800 °C. Changing the final polishing direction from parallel toperpendicular to the loading direction caused the spallation ratio to be increased and reduced the strain initiating the first spallation. Adhesion energiesof scales on the studied samples were in the range of 159-384J.m^–2.

Abstract: The problem of punching tools resistance increasing is investigated. Methods for intermetallic coatings synthesis are investigated. Mathematical model of vacuum ion-plasma deposition process allowing predicting coatings composition basing on intermetallic system Ti-Al was developed. Experimental verification confirmed the adequacy of the computer model. The technology hardening punching tools with wear-resistant coatings deposition based on intermetallic Ti-Al system on pre-nitriding surface in vacuum was developed. Production tests of the hardened punching tools were carried out.

Abstract: Nitride coatings were deposited by vacuum arc plasma, in an atmosphere of argon and nitrogen using different deposition conditions of part location and configuration, angle between plasma flow and processing surface. The coating thickness, part dimensions and surface roughness were measured before and after coating deposition. The type of part poor shape precision after coating deposition by vacuum arc plasma was defined. An impact of coating deposition by vacuum arc discharge on the part dimensional and form accuracy was revealed. The effect of parts location on dimensional and radial surfaces form accuracy was induced. The effect of coating surface polythickness on part dimensional and form accuracy for parts with different stiffness was defined. The impact of part location area and parts quantity on coating thickness, surface roughness, dimensional and form accuracy of part was revealed. The coating thickness distribution law, parts quality class and accuracy degree after vacuum ion plasma coating deposition were assigned.

Abstract: Residual stress occured in welding process generally causes reduction in the strength of welded joints, shortens the fatigue life, and brings about the distortion of the workpiece. In this research, finite element analysis (FEA) model of the butt-joint tungsten inert gas (TIG) welding process with the application of birth-death technique was presented. The material used in this research was AISI 304 stainless steel. The FEA model was constructed on a simulation software, ANSYS. The predictive residual stress from a welding condition obtained from the FEA model was verified by the value measured from X-ray diffraction (XRD) machine. Effects of four welding process parameters: efficiency, welding speed, arc current, and arc voltage on residual stress at the center of the welded joint and at the heated affected zone (HAZ) were investigated. The welding conditions were generated by varying these four main effects according to the Taguchi design of experiment technique (L8 orthogonal array). In general, compressive residual stress is beneficial to the strength and fatigue life of welded joints. For the Taguchi method the larger is better constraint was used; larger means higher magnitude of compressive residual stress. The predictive residual stress results obtained from the FEA model were consistent with the values obtained from the XRD measurement. The result suggested that the most significant effect was the arc current, followed by the arc voltage, welding speed, and the efficiency. The response optimizer in MINITAB software showed the optimal magnitude of compressive residual stress values of about 52 MPa obtained at the arc current of 126 Ampere, arc voltage of 17 Volts, welding speed of 110 mm/min, and the efficiency of 80%.

Abstract: This paper presents an investigation of research objectives on the effect of tilt angle on microstructure and mechanical properties of dissimilar aluminum alloy sheets between AA5083 and AA6061, 5mm plates by using Friction Stir Welding (FSW) process in butt joint. The base materials of AA5083 and AA6061 were located on the retreating side (RS) and advancing side (AS), respectively. The welding process and the welding parameters such as tool pin profile, tool rotation speed, welding speed and tilt angle influenced the mechanical properties of the Friction Stir Welding joints significantly. For this experiment, the Friction Stir Welding materials joined under five different tilt angles (from 0^oto 4^o) with 86mm/min of welding speed and 910 rpm of tool rotation speed which were set similarly. Microscopic examination on the weld samples showed significant variation in the microstructure especially in the region of heat-affected zone (HAZ), weld nugget or dynamically recrystallized zone (DXZ) and in the base metal.