International Journal of Machining and Machinability of Materials, 2006
Int. J. Machining and Machinability of Materials, Vol. 1, No. 1, 2006 ... Effects of cryogenic co... more Int. J. Machining and Machinability of Materials, Vol. 1, No. 1, 2006 ... Effects of cryogenic cooling by liquid nitrogen jets on tool wear, surface finish and dimensional deviation in turning different steels ... Department of Industrial and Production Engineering, Bangladesh University of ...
In this study, an artificial neural network (ANN) based predictive model of average surface rough... more In this study, an artificial neural network (ANN) based predictive model of average surface roughness in turning hardened EN 24T steel has been presented. The prediction was performed by using Neural Network Tool Box 7 of MATLAB R2015a for different levels of cutting speed, feed rate, material hardness and cutting conditions. To be specific the dry and high pressure coolant (HPC) jet environments were explored as cutting conditions. The experimental runs were determined by full factorial design of experiment. Afterward the 3-n-1, 3-n-2 and 4-n-1 ANN architectures were trained by utilizing the Levenberg–Marquardt (LM), Bayesian regularization (BR) and scaled conjugate gradient (SCG) algorithms, and evaluated based on the lowest root mean square error (RMSE). The 3-10-1 and 3-4-2 ANN models, trained by BR, revealed the lowest RMSE. A good prediction fit of the models was established by the regression coefficients higher than 0.997. At last, the behavior of the surface roughness in respect of speed-feed-hardness for dry and HPC conditions has been analyzed. The HPC reduced surface roughness by the efficient cooling and lubrication whereas the higher hardness of material induced higher average surface roughness due to higher restraining force against tool imposed cutting force.
□ Residual stress is one of the critical characteristics for assessing the qualities and function... more □ Residual stress is one of the critical characteristics for assessing the qualities and functionalities of machined products in light of its direct effect on endurance limit, distortion, and corrosion resistance. Primary factors responsible for residual stresses distribution include mechanical effects, thermal effects, microstructure evolutions, and a combination of these mechanisms. This study investigates the effects of minimum quantity lubrication (MQL) on machining force, temperature and residual stress through a physics-based modeling method. Both the lubrication and cooling effects caused by MQL air-oil mixture contribute to changes in friction due to boundary lubrication as well as variations in the thermal stress due to heat loss. The modified Oxley's model is employed to predict the cutting force and temperature directly from cutting conditions. The predicted cutting force and temperature are then coupled into a thermal-mechanical model which incorporates the kinematic hardening and strain compatibility to predict the machining-induced residual stress under lubricated conditions. The proposed analytical method is experimentally verified by orthogonal cutting tests for AISI 4130 alloy steel in the context of forces, temperatures, and residual stresses.
In this paper, the performance of an uncoated tungsten carbide insert (SNMG 120408 TTS;P30 ISO sp... more In this paper, the performance of an uncoated tungsten carbide insert (SNMG 120408 TTS;P30 ISO specification; Wadia) was investigated during turning of AISI 1040 steel. The PSBNR 2525 M12 tool holder was used. Cutting tests were performed with constant depth of cut and at various cutting speeds and feed rates to investigate the performance of the tool under dry and cryogenic cooling conditions. The chips produced by the insert during experimental trials were examined to determine the secondary shear zone, chip thickness (a2), chip reduction coefficient (ζ) and chip contact length. The tool performs best under cryogenic cooling conditions, as lower cutting forces, very good surface finish could be obtained and chips with lowering the chip thickness (a2) could be produced that contributed to low chip strain and therefore to low residual stresses on the work piece as compared to dry condition.
International Journal of Machining and Machinability of Materials, 2006
Int. J. Machining and Machinability of Materials, Vol. 1, No. 1, 2006 ... Effects of cryogenic co... more Int. J. Machining and Machinability of Materials, Vol. 1, No. 1, 2006 ... Effects of cryogenic cooling by liquid nitrogen jets on tool wear, surface finish and dimensional deviation in turning different steels ... Department of Industrial and Production Engineering, Bangladesh University of ...
In this study, an artificial neural network (ANN) based predictive model of average surface rough... more In this study, an artificial neural network (ANN) based predictive model of average surface roughness in turning hardened EN 24T steel has been presented. The prediction was performed by using Neural Network Tool Box 7 of MATLAB R2015a for different levels of cutting speed, feed rate, material hardness and cutting conditions. To be specific the dry and high pressure coolant (HPC) jet environments were explored as cutting conditions. The experimental runs were determined by full factorial design of experiment. Afterward the 3-n-1, 3-n-2 and 4-n-1 ANN architectures were trained by utilizing the Levenberg–Marquardt (LM), Bayesian regularization (BR) and scaled conjugate gradient (SCG) algorithms, and evaluated based on the lowest root mean square error (RMSE). The 3-10-1 and 3-4-2 ANN models, trained by BR, revealed the lowest RMSE. A good prediction fit of the models was established by the regression coefficients higher than 0.997. At last, the behavior of the surface roughness in respect of speed-feed-hardness for dry and HPC conditions has been analyzed. The HPC reduced surface roughness by the efficient cooling and lubrication whereas the higher hardness of material induced higher average surface roughness due to higher restraining force against tool imposed cutting force.
□ Residual stress is one of the critical characteristics for assessing the qualities and function... more □ Residual stress is one of the critical characteristics for assessing the qualities and functionalities of machined products in light of its direct effect on endurance limit, distortion, and corrosion resistance. Primary factors responsible for residual stresses distribution include mechanical effects, thermal effects, microstructure evolutions, and a combination of these mechanisms. This study investigates the effects of minimum quantity lubrication (MQL) on machining force, temperature and residual stress through a physics-based modeling method. Both the lubrication and cooling effects caused by MQL air-oil mixture contribute to changes in friction due to boundary lubrication as well as variations in the thermal stress due to heat loss. The modified Oxley's model is employed to predict the cutting force and temperature directly from cutting conditions. The predicted cutting force and temperature are then coupled into a thermal-mechanical model which incorporates the kinematic hardening and strain compatibility to predict the machining-induced residual stress under lubricated conditions. The proposed analytical method is experimentally verified by orthogonal cutting tests for AISI 4130 alloy steel in the context of forces, temperatures, and residual stresses.
In this paper, the performance of an uncoated tungsten carbide insert (SNMG 120408 TTS;P30 ISO sp... more In this paper, the performance of an uncoated tungsten carbide insert (SNMG 120408 TTS;P30 ISO specification; Wadia) was investigated during turning of AISI 1040 steel. The PSBNR 2525 M12 tool holder was used. Cutting tests were performed with constant depth of cut and at various cutting speeds and feed rates to investigate the performance of the tool under dry and cryogenic cooling conditions. The chips produced by the insert during experimental trials were examined to determine the secondary shear zone, chip thickness (a2), chip reduction coefficient (ζ) and chip contact length. The tool performs best under cryogenic cooling conditions, as lower cutting forces, very good surface finish could be obtained and chips with lowering the chip thickness (a2) could be produced that contributed to low chip strain and therefore to low residual stresses on the work piece as compared to dry condition.
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Papers by Nikhil Ranjan Dhar