The Altemp HX is a nickel-based superalloy having many applications in chemical, nuclear, aerospace, and marine industries. Machining such superalloys is challenging as it may cause both tool and ...surface damage. WEDM, a non-contact machining technique, can be employed in the machining of such alloys. In the present study, different input parameters which include pulse on time, wire span, and servo gap voltage were investigated. The cutting velocity, surface roughness, recast layer, and microhardness variations were examined on the WEDMed surface. The genetic algorithm was used to optimize the cutting velocity and surface roughness, thereby improving the overall quality of the product. The highest recast layer values were recorded as 25.8 µm, and the lowest microhardness was 170 HV. Response surface methodology and artificial neural network were employed for the prediction of cutting velocity and surface roughness. Artificial neural network prediction technique was the most efficient method for the prediction of response parameters as it predicted an error percentage lesser than 6%.
This study investigates the effect of different heat treatment procedures on tensile, hardness, and fatigue properties of additively manufactured AlSi10Mg. Tensile properties were evaluated for ...different material conditions, i.e., as-built (AB), direct aging (DA), solution treatment (ST), and T6 heat treatment. It was observed that the as-built samples had the highest yield and tensile strength with limited ductility while increasing the peak heat treatment temperature improves the ductility but at the cost of strength. The microhardness also followed a declining trend with an increase in peak heat treatment temperature. An empirical correlation, validated by experimental data, was established to predict the properties based on peak heat treatment temperatures. Based on the observed test results, four material conditions were selected for evaluating the high cycle fatigue (HCF) properties, i.e., AB, SR, DA, and T6. The as-built samples displayed superior fatigue resistance while that of T6 heat treated samples were most deteriorated. The heat treatment-induced microstructural transformation influences the tensile, hardness, and fatigue properties of the SLM AlSi10Mg, mainly due to the disintegration of continuous Al–Si cellular network and the subsequent formation of discrete Si-particles at high temperatures. The interaction between microstructurally-controlled mechanical properties, associated heat treatment process and the intrinsic damage mechanisms was investigated in detail and discussed later in this study.
Nickel-based superalloys are classified under difficult to machine materials due to its higher affinity to tool materials and low thermal diffusivity. Wire electric discharge machining (WEDM) is a ...spark eroding technique for precise machining of such superalloys with complex machining geometries. Tapering in WEDM has many disadvantages like wire break, angular inaccuracies and dielectric distribution for better surfaces. In this paper, a unique method was developed and employed to achieve taper surface by tilting the workpiece using a slant type taper fixture for machining of tapered surfaces. Different aspects like cutting thickness, surface roughness, slant angle, surface crack density and width of cut were examined for five distinct cutting speed parameters at different angles, namely 0°, 15°, 30°, 45° and 60°. In the present research work, Hastelloy X was machined using zinc-coated copper wire and cutting speed was ranged between 0.16 and 2.49 mm/min. The slant angle was observed to be independent of cutting speed, and it was influenced by wire vibration, manufacturing imprecisions of slant fixture. It was found that as the cutting speed increases, surface crack density and surface roughness also increase. It was observed that both the parameters increased with the increase in the angle of cut from 0° to 60° although the cutting speed decreased.
The oblique/tapered machining is a unique method in wire electric discharge machining to get taper profiles difficult to machine materials. These profiles have many applications like dies, nozzles, ...inserts, cutting tools and other components. In the present study, a simple square profile is machined using a slant type fixture to achieve a tapered profile made of Hastelloy X. A simple square is machined at different slant angles to get a 0°, 15° and 30° tapered profiles. This paper aims to study the effects of the machining parameters like wire guide distance, wire offset, corner dwell time and cutting speed override on the area of machined profiles. Both scanning electron microscope and coordinate measuring machine were used to measure the areas of 1mm and 5mm. It is observed that as the wire guide distance and cutting speed override increases the area decreases. Whereas in case of wire offset, as offset increases the areas also increase and corner dwell time doesn't affect on the area. As the angle increased the area also increased leading to bigger taper profiles.
Abstract
Due to extensive mechanical load bearing capability under high temperature and pressure, Nickel based super alloys are widely incorporated in aerospace and aviation industries in various ...sections like chemical, fuselage, engine, combustor components, etc. Hastelloy-X is a Ni-based super alloy consisting mainly Ni, Cr, Fe, Mo and Co, which has good corrosion and heat resistance capacity. Since Hastelloy-X is a difficult-to-machine material, a non-conventional Wire Electric Discharge Machining is used. This work aims at machining characteristics study of WEDM of Hastelloy-X and prediction of major machining performances using Artificial Neural Network (ANN). At first, full factorial design of experiments was set using Minitab which includes four input machining parameters namely pulse-on time (T-on), pulse-off time (T-off), wire feed (WF) and servo voltage (SV); kept at three levels; high, medium and low. Total 81 experimental runs were performed. After machining on WEDM, machining performances MRR (material removal rate) and SR (surface roughness) were measured. There after the neural network is trained in nntool in MATLAB to predict the MRR and SR. The predicted model has mean absolute percentage error (MAPE) of 6.371% for MRR prediction and 5.92% for SR prediction while the MSE (Mean Square Error) was found to be 0.389 and 0.129 for MRR and SR respectively. The trained network has training, validation and testing regression coefficient (R) values of 0.9756, 0.9916 and 0.9662 respectively. And the overall R value was 0.97746. After prediction, the samples with extreme values of actual and predicted outputs were studied for other machining responses like recast layer, surface cracks and kerf width. Out-turn of this research can be utilized for machining hard to machine materials in a high precision WEDM for different applications.
Wire electric discharge machining non-conventional process that removes materials by thermal erosion. Tapering in WEDM has many applications in machining accurate geometric profiles. In the present ...investigation, a slant type taper machining was performed to produce taper profiles with the help of the slant fixture. The machining parameters such as wire guide distance, corner dwell time, wire offset and cutting speed override was employed to find the variation in the taper profile area. A simple square profile of 1mm, 3mm and 5mm was machined at different slant angles namely 0°, 15° and 30°. It was observed that each parameter yielded different profile areas. The artificial neural network was used for the forecasting the areas of 1mm, 3mm and 5mm square for different parameters. The optimum artificial neural network model was experimentally validated and the errors were ranging from 0-10%.
Machining of polymeric composite is inevitable during assembly of components. In view of making holes on structural composites, drilling is essential and a study to optimize the machining parameters ...is very important. The present study has been made to investigate the defaces and cutting forces associated during drilling of natural fiber reinforced plastics. Plastic composite has been manufactured using chemically treated
vetiveria zizanioides
as the reinforcement and polyester as the matrix. The composite has been drilled several times on the basis of central composite design. Speed and feed rate of the spindle, point angle and diameter of the tool are considered as the input parameters. Deface of each hole during entry and exit, thrust force and torque have been measured as the output parameters. A fuzzy model has been created and a comparative study between the central composite design and fuzzy model is made. The design has been optimized with the objective of minimizing the output parameters and a set of confirmatory experiments have been conducted. The central composite model has been validated by comparing it with the fuzzy model and confirmatory runs. The comparison presented only a minimal error and hence the modeling by central composite design and fuzzy are consummate.
Wire electric discharge machining (WEDM) is nonconventional machining that provides machining solutions irrespective of the material hardness. In the present study, a simple profile was machined on ...Microfer 4722 at different slant angles using to know the effect of machining parameters. A unique method of obtaining taper components was employed by slant type taper fixture to avoid the disadvantages of the conventional method. The profiling speed, profile roughness, profiling error (Corner error), recast layer thickness, micro-hardness, microstructural and metallurgical changes of the machined component were investigated. As the taper of the component increases the profile roughness, corner error increases although profiling speed decreases. It is observed that recast layer thickness decreases as the taper of the component increases. A contrasting phenomenon is observed in the case of hardness at the WEDM surface. The metallurgical changes like the addition of Cu, Zn and O in the nickel-based alloy after machining from WEDM at different slant angles are highlighted. It is observed that residual stress decreased as the slant angles increased from 0° to 30° during slant type profiling.
Wire electro-discharge machining (WEDM) is a widely used machining process for machining of difficult to cut materials, which are used in precision profile applications like dies, metal stampings, ...and gas turbine parts. In the present research work, a new slant type taper fixture was used to obtain angular machining of triangular shape slots of sides 1mm, 3mm and 5mm machined both in 0° and 30° as slant angles on Hastelloy X. The corner radius and corner errors were investigated for different machining parameters like corner dwell time (CDT), offset distance (WO), wire guide distance (WGD) and cutting speed override (CSO) using L16 orthogonal array for both the slant angles. SEM micrographs indicated that corners were with lower radii at 30° than in 0° slant profiles, at lowest and highest cutting speeds. The main effects plot showed that the corner radius increases with the increase in wire offset and wire guide distance parameters. The increase in corner dwell time has an adverse effect on the corner radius. The triangles were machined at different cutting speeds from 0.47 to 1.51 mm/min with various parameters; it was observed that as the corner radius decreases the corner error also reduces. However, the corner radius and corner error can be minimized by selecting an optimized cutting parameter.
In the present study, taper cutting is performed with the aid of a uniquely designed fixture. This is attempted to avoid the difficulties in tapering using wire electric discharge machining like wire ...break, dimensional error, guide wear, non-uniform flushing and low surface quality. An investigation of output parameters was made during taper machining using a fixture. The cutting rate (CR) and surface roughness (SR) were considered for response surface optimization (RSM) as they were important response parameters that indicate the quality of a machined component. It is observed that servo gap voltage and pulse act contrastingly on the output parameters. For achieving a trade-off of input parameters with output responses, RSM optimization is selected during taper profiling. There were 3-5% variations for both CR and SR when compared to experimental and RSM optimal values. The tapered profile slots of different angles like 0°, 15° and 30° were machined on Pyromet-680 using optimal machining parameters. The effect of different profiling parameters like wire distance between guides (WD), dwell time (DT), profile offset (PO) and cutting speed override (CO) on output responses like CR and SR was analyzed. Adaptive neuro-fuzzy interference system (ANFIS) and artificial neural network (ANN) models have been established for the prediction of the output responses. The validation is performed by experimentation, and the prediction errors ranged from 0 to 5% for both the responses CR and SR in ANFIS models. So ANFIS models proved to be the most efficient as there is an improvement of 45-50% in prediction compared to ANN models.
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