Performance assessment of energy efficient and eco-friendly turning of Nimonic C-263: A comparative study on MQL and cryogenic machining

Nimonic C-263 is predominantly used in the manufacturing of heat susceptible intricate components in the gas turbine, aircraft, and automotive industries. Owing to its high strength, poor thermal conductivity, the superalloy is difficult to machine and causes rapid tool wear during conventional machining mode. Moreover, the unpleasant machining noise produced during machining severely disrupts the tool engineer’s concentration, thereby denying a precise and environment friendly machining operation. Hence, close dimensional accuracy, superior machined surface quality along with production economy, and pleasant work environment for the tool engineers is the need of an hour of the current manufacturing industry. To counter such issues, the present work attempts to compare and explore the machinability of two of the most popular machining strategies like minimum quantity lubrication (MQL) and cryogenic machining process during turning of Nimonic C-263 work piece in order to achieve an ideal machining environment. The machining characteristics are compared in terms of surface roughness (SR), power consumption (P), machining noise (S), nose wear (NW), and cutting forces (CF) to evaluate the impact of machining variables like cutting speed (Vc), feed (f), and depth of cut (ap) with a detailed parametric study and technical justification. Yet again, an investigation is conducted to compare both the machining strategies in terms of qualitative responses like chip morphology, total machining cost, and carbon emissions. The study revealed that cryogenic machining strategy is adequately proficient over MQL machining to deliver energy proficient and gratifying work environment for the tool engineers by reducing the cost of machining and improving their work efficiency.

Optimization of Process Parameters for Turning Hastelloy X under Different Machining Environments Using Evolutionary Algorithms: A Comparative Study

In this research work, the machinability of turning Hastelloy X with a PVD Ti-Al-N coated insert tool in dry, wet, and cryogenic machining environments is investigated. The machinability indices namely cutting force (CF), surface roughness (SR), and cutting temperature (CT) are studied for the different set of input process parameters such as cutting speed, feed rate, and machining environment, through the experiments conducted as per L27 orthogonal array. Minitab 17 is used to create quadratic Multiple Linear Regression Models (MLRM) based on the association between turning parameters and machineability indices. The Moth-Flame Optimization (MFO) algorithm is proposed in this work to identify the optimal set of turning parameters through the MLRM models, in view of minimizing the machinability indices. Three case studies by considering individual machinability indices, a combination of dual indices, and a combination of all three indices, are performed. The suggested MFO algorithm’s effectiveness is evaluated in comparison to the findings of Genetic, Grass-Hooper, Grey-Wolf, and Particle Swarm Optimization algorithms. From the results, it is identified that the MFO algorithm outperformed the others. In addition, a confirmation experiment is conducted to verify the results of the MFO algorithm’s optimal combination of turning parameters.

Effect of indirect cryogenic cooling on the machining accuracy and tool vibration in the turning of polysulfone

Cutting deformation and cracks are common problems during the machining of precise polymer parts. This paper aims to explore the effect of different conditions on the contour profile of machined surfaces and tool vibration. Turning experiments of polysulfone (PSU) were performed under three conditions: dry, conventional flood cooling, and indirect cryogenic cooling. Then the formation mechanism of machined surfaces contour profile under different cutting conditions was clarified by the Eyring equation from the perspective of molecular chains relaxation time. Furthermore, extension models of crazing and cracks were proposed through the microscopic morphology of machined surfaces and the discriminant formula of crazing generation to explain the differences in tool vibration. The results indicated that the indirect cryogenic cooling condition with the internally cooled cutting tool could significantly improve the machinability of polysulfone, and have an excellent performance on the contour profile of machined surfaces with and the inhibition of crazing. Compared with dry and conventional flood cooling, indirect cryogenic cooling could reduce the mean of the Contour profile (Ra) by 40.3% and 30.1% and the machining accuracy error by 41% and 83%. The indirect cryogenic cooling method proposed in this work provides a reference for the cryogenic machining for polymers.

An Experimental and Finite Element Approach for a Better Understanding of Ti-6Al-4V Behavior When Machining under Cryogenic Environment

Due to increasing demand in manufacturing industries, process optimization has become a major area of focus for researchers. This research optimizes the cryogenic machining of aerospace titanium alloy Ti-6Al-4V for industrial applications by studying the effect of varying the nozzle position using two parameters: the nozzle’s separation distance from the tool–chip interface and its inclination angle with respect to the tool rake face. A finite element model (FEM) and computational fluid dynamics (CFD) model are used to simulate the cryogenic impingement of cryogenic carbon dioxide on the tool–workpiece geometry. Experiments are conducted to evaluate cutting forces, tool wear, and surface roughness of the workpiece, and the results are related to the CFD and FEM analyses. The nozzle location is shown to have a significant impact on the cutting temperatures and forces, reducing them by up to 45% and 46%, respectively, while the dominant parameter affecting the results is shown to be the separation distance. Cryogenic machining is shown to decrease adhesion-diffusion wear as well as macroscopic brittle chipping of the cutting insert compared to dry turning, while the workpiece surface roughness is found to decrease by 44% in the case of cryogenic machining.

Cryogenic machining to enhance surface finish of a biomedical grade ultra-high-molecular weight polyethylene

In recent years, polymeric materials are being used at an increasing rate in the biomedical industry. In particular, Ultra-High-Molecular Weight Polyethylene (UHMWPE), a thermoplastic polymer characterized by high toughness, good chemical stability and self-lubricating properties, is an ideal candidate for the manufacture of bearing implants used in hip or knee replacements. Nevertheless, it is difficult to achieve a good level of surface finish when turning it, because of its high instability at increasing temperature. In the present study, cryogenic machining was applied instead of dry cutting to machine a biomedical grade UHMWPE at different cutting speeds. The surface finish was assessed in terms of surface roughness, crystallinity degree and hardness in correspondence of the surface. To correlate machinability results with the UHMWPE mechanical behaviour, uniaxial tensile tests were performed in a wide range of temperatures. The obtained results showed that the application of cryogenic machining was an efficient mean to increase the surface finish: in fact, smoother and harder surfaces were obtained regardless of the adopted cutting parameters.