The residual stresses generated in the machined work piece have detrimental effect on fatigue life, corrosion resistance and tribological properties. However, the effect of cutting and vibration ...parameters on residual stresses in Ultrasonic Assisted Turning (UAT) has not been dealt with. The present paper highlights the effect of feed rate, depth of cut, cutting velocity and percentage intensity of ultrasonic power on residual stress generation. XRD analysis has been carried out to measure the residual stress while turning 4340 hardened steel using UAT. The experiments were performed based on response surface methodology to develop statistical model for residual stress. The outcome of ANOVA revealed that percentage intensity and feed rate significantly affect the residual stress generation. The significant interactions between process parameters have also been presented tin order to understand the thermo-mechanical mechanism responsible for residual stress generation.
This novel work presents the comparison of a newly developed ultra-high voltage electrostatic minimum quantity lubrication (EMQL) using a customized nozzle with the MQL technique as an alternative ...cooling/lubricating method in turning processes of 15–5 PHSS. The optimum voltage for EMQL within the range of 0–25 kV has been identified based on tribological performance. Besides, surface roughness has been measured to identify the impact of electrostatically charged mist for turning 15-5 PHSS. Finally, tool wear tests are performed for MQL and EMQL at optimized voltage. The EMQL at optimized electrostatic voltage resulted in 38% decreased tool wear as compared to conventional MQL for 2400 mm cutting length.
•A novel Electrostatic Minimum Quantity Lubrication (EMQL) setup is compared with MQL at various electrostatic voltage.•Electrostatic voltage is optimized based on results of droplet quality, tribological properties and surface roughness.•EMQL at optimized electrostatic voltage resulted in 38% decreased tool wear as compared to conventional MQL.
In this work, sustainable hybrid cryogenic MQL cooling/lubrication techniques viz. Ranque- Hilsch Vortex tube plus MQL (RHVT + MQL), liquid nitrogen plus minimum quantity lubrication (N2+MQL), and ...liquid nitrogen (N2) are presented for turning Ti–6Al–4V utilizing CVD coated carbide insert. The tool wear, surface roughness, micro-hardness, specific cutting energy, and chip morphology are considered under sustainable cooling conditions and compared with the dry condition. The outcome revealed that the N2+MQL reduced the tons of annual coolant consumption attaining smooth surface quality, minimum built-up-edges of chips, and tool wear. Besides, minimum specific cutting energy and surface hardness achieved under N2+MQL among all cooling conditions. This endeavor is peculiar integrating sustainability and machining perspective under advanced cooling techniques for industrial application of Ti–6Al–4V.
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•Turning of Ti–6Al–4V alloy under hybrid cryo-lubrications were performed.•Tribological aspects in terms of tool wear, surface roughness and micro hardness was evaluated.•Specific cutting energy and chip observations were investigated.•SEM of tools, tool profile and 3D machined surface were analysed.
Issues related to the machinability of difficult-to-machine materials such as Titanium and Nickel base superalloys are well explicated in the literature. In this regard, a novel study, applying ...ultrasonic vibration along with MQL and LCO2, is proposed to enhance the machinability of Ti-6Al-4V. In this regard, this article attempts to analyze machinability of Ti-6Al-4V in conventional and Ultrasonic Assisted Turning (UAT) under dry, wet, MQL and LCO2. The experiments are performed on an in-house developed ultrasonic assisted turning setup, keeping all the machining parameters constant. The main tool wear mechanisms observed are diffusion, adhesion, abrasion, and built-up edge formation in both cutting strategies. Moreover, the LCO2 and ultrasonic vibration significantly reduce specific cutting energy without compromising the surface roughness and tool life. Ultimately, the LCO2, along with ultrasonic assisted turning, promotes sustainability in the machining of Ti-6Al-4V.
•Novel combination of eco-friendly cooling and lubrication techniques i.e., MQL, LCO2 and ultrasonic vibration is used for machining Ti-6Al-4V.•Tool wear, power consumption, surface roughness and specific cutting energy are compared under dry, wet MQL and LCO2.•Comparative performance of Ti-6Al-4V is analysed in ultrasonic assisted and conventional turning.•The LCO2 considerably reduces the tool wear, specific cutting energy without compromising the surface quality.•The LCO2 along with ultrasonic assisted turning is attained the sustainability in machining Ti-6Al-4V.
In industry, many taper shafts are designed with tolerances of a few microns. To cut them in finish turning, paths of the tool in virtual machining should be accurately generated beforehand. For this ...purpose, the dimension errors and surface roughness of the virtually cut workpiece should be predicted. Unfortunately, the current tool path generation methods cannot accurately calculate the errors and the roughness, resulting in the taper errors larger than the part tolerance. Our research formulates equations of the effective turning edge to accurately calculate the dimension errors and the surface roughness, and then proposes a new approach to CNC programming for high-precision CNC turning. It lays a theoretical foundation of modeling parts in virtual turning and can generate tool paths to machine taper parts with high accuracy.
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It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication (MQL) technology. Nevertheless, for aeronautical ...difficult-to-machine materials, MQL couldn’t meet the high demand of cooling and lubrication due to high heat generation during machining. Nano-biolubricants, especially non-toxic carbon group nano-enhancers (CGNs) are used, can solve this technical bottleneck. However, the machining mechanisms under lubrication of CGNs are unclear at complex interface between tool and workpiece, which characterized by high temperature, pressure, and speed, limited its application in factories and necessitates in-depth understanding. To fill this gap, this study concentrates on the comprehensive quantitative assessment of tribological characteristics based on force, tool wear, chip, and surface integrity in titanium alloy and nickel alloy machining and attempts to answer mechanisms systematically. First, to establish evaluation standard, the cutting mechanisms and performance improvement behavior covering antifriction, antiwear, tool failure, material removal, and surface formation of MQL were revealed. Second, the unique film formation and lubrication behaviors of CGNs in MQL turning, milling, and grinding are concluded. The influence law of molecular structure and micromorphology of CGNs was also answered and optimized options were recommended by considering diverse boundary conditions. Finally, in view of CGNs limitations in MQL, the future development direction is proposed, which needs to be improved in thermal stability of lubricant, activity of CGNs, controllable atomization and transportation methods, and intelligent formation of processing technology solutions.
•A multi-layer perceptron model for straight-turn binary classification training using K-Fold cross validation is proposed.•A convolutional neural network-based model is proposed to proform turning ...classification between Omega turn and T turn.•The proposal of line and turn segmentation algorithms and turn type recognition algorithms provides new methods for estimating the efficiency of agricultural machinery operations.
GPS technology is an indispensable technique in “precision agriculture”. In the field of path planning, the evaluation of planned trajectories is based on GPS data. However, due to the unstructured operating environment, the existing methods for evaluating the efficiency of actual operating trajectories are not yet fully developed. In the context of agricultural machinery GPS trajectories, headland turning of the field is considered a non-working segment, which related to evaluation standard for trajectory planning efficiency in many studies. This paper proposes a processing method that evaluates GPS trajectories efficiency. A turning extraction algorithm based on changes in the angle of the agricultural machine’s driving direction is proposed. The turning parts of the raw GPS data are preliminarily extracted, and a method for constructing a turning extraction dataset is presented. Then a multi-layer perceptron model for straight-turn binary classification training using K-Fold cross validation is designed and applied, which can implement robust segmentation of agricultural machinery trajectory points in actual environment. Two methods for building different turning classification datasets are proposed, and turning classification is performed using two deep learning models. A convolutional neural network-based model classifies headland turnings by their normalized sequences’ visualization images, while a long short-term memory network-based model utilizes the trajectory point sequences. The CNN-based model performs relatively better than the LSTM-based model. Finally, some commonly used GPS trajectory efficiency evaluation standards in the field of agricultural machinery path planning are combined to evaluate the efficiency of actual GPS trajectories of agricultural machinery.
The present study illustrates the performance of three different cutting tool materials, namely: PCBN, TiN coated PCBN, and mixed aluminum ceramic (Al2O3+TiC) in the turning of medium hardened D2 ...tool steel (52 HRC). Formation of Cr–O tribofilms on the ceramic tool surface as a result of interaction with the workpiece material and environment (identified by X-ray Photoelectron Spectroscopy) leads to improvement of lubricating properties at the tool/chip interface. Obtained results revealed that the mixed alumina ceramic tool can outperform both types of PCBN under different machinability criteria.
•Mixed alumina ceramic tool gives longer tool life and lower cutting forces than PCBN.•Friction kinetics between each tool material and workpiece material control tool wear.•TiN coating on PCBN does not improve its performance.•Surface tribo-films formed on the worn surface were studied using X-ray photoelectron spectroscopy (XPS).
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