Showing papers on "Machining published in 2022"
TL;DR: In this paper , the authors present a systematic scheme of drilling damage suppression from the overall drilling system, including the formation mechanism of damage at different hole positions, including exit push-out delamination, entrance peel-up delamination and fiber pull-out, and the suppression strategies are systematically reviewed from the following four aspects: drilling techniques and methods, drilling conditions, tool design, and multi-techniques integration.
143 citations
TL;DR: In this paper , the authors summarized an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature.
Abstract: Abstract Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.
109 citations
TL;DR: In this paper , a comprehensive quantitative assessment of processability based on tribological, thermal, and machined surface quality aspects for nano-enhanced biolubricant (NEBL) application in turning, milling, and grinding is presented.
Abstract: Abstract To eliminate the negative effect of traditional metal-working fluids and achieve sustainable manufacturing, the usage of nano-enhanced biolubricant (NEBL) is widely researched in minimum quantify lubrication (MQL) machining. It’s improved tool wear and surface integrity have been preliminarily verified by experimental studies. The previous review papers also concluded the major influencing factors of processability including nano-enhancer and lubricant types, NEBL concentration, micro droplet size, and so on. Nevertheless, the complex action of NEBL, from preparation, atomization, infiltration to heat transfer and anti-friction, is indistinct which limits preparation of process specifications and popularity in factories. Especially in the complex machining process, in-depth understanding is difficult and meaningful. To fill this gap, this paper concentrates on the comprehensive quantitative assessment of processability based on tribological, thermal, and machined surface quality aspects for NEBL application in turning, milling, and grinding. Then it attempts to answer mechanisms systematically considering multi-factor influence of molecular structure, physicochemical properties, concentration, and dispersion. Firstly, this paper reveals advanced lubrication and heat transfer mechanisms of NEBL by quantitative comparison with biolubricant-based MQL machining. Secondly, the distinctive filmformation, atomization, and infiltration mechanisms of NEBL, as distinguished from metal-working fluid, are clarified combining with its unique molecular structure and physical properties. Furtherly, the process optimization strategy is concluded based on the synergistic relationship analysis among process variables, physicochemical properties, machining mechanisms, and performance of NEBL. Finally, the future development directions are put forward aiming at current performance limitations of NEBL, which requires improvement on preparation and jet methods respects. This paper will help scientists deeply understand effective mechanism, formulate process specifications, and find future development trend of this technology.
107 citations
TL;DR: In this paper , the authors summarized an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature.
Abstract: Abstract Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.
104 citations
01 Jan 2022
TL;DR: In this paper , the deformation and removal mechanisms of gallium nitride (GaN) single crystals involved in the ultra-precision machining process are not well revealed and few investigations on the grinding of GaN crystals have been reported.
Abstract: Despite being the most promising third-generation semiconductor materials, the deformation and removal mechanisms of gallium nitride (GaN) single crystals involved in the ultra-precision machining process are not well revealed and few investigations on the grinding of GaN crystals have been reported, which hinders the development of high-efficiency and ultra-precision manufacturing of GaN components. Self-rotating grinding tests of GaN crystals were performed, and the results indicated that abrasive size had a significant influence on the surface morphology and roughness, in comparison with wheel rotational speed and feed speed. As the abrasive size decreased from 18 μm to 1.6 μm, the brittle fracture-dominated surface gradually changed to a full-plastic surface without brittle fractures and cracks. An ultra-smooth surface with a roughness of 1 nm in Sa was acquired using #8000 grinding wheels and a spark-out time of 10 min, which indicated that the machining technology of “grinding instead of polishing” of GaN crystals was achieved in this work. The plastic deformation mechanism of GaN crystals induced by ultra-precision machining was investigated using a cross-sectional TEM method and MD simulation, and both experimental and simulation results indicated that the plastic deformation involved in the scratching process was caused by the formation of polycrystalline nanocrystals, high-angle lattice misorientations, and close-to-atomic-scale defects, including stacking faults, dislocations and serious lattice distortions, along with a small amount of amorphous and phase transitions. There was an obvious delamination phenomenon in the plastic deformation zone. This research enhances the understanding of the deformation and damage mechanisms of GaN crystals involved in the ultra-precision machining process and is of significance for achieving the high-efficiency and high-accuracy manufacturing of GaN components.
104 citations
TL;DR: In this paper, the deformation and removal mechanisms of gallium nitride (GaN) single crystals involved in the ultra-precision machining process are not well revealed and few investigations on the grinding of GaN crystals have been reported.
Abstract: Despite being the most promising third-generation semiconductor materials, the deformation and removal mechanisms of gallium nitride (GaN) single crystals involved in the ultra-precision machining process are not well revealed and few investigations on the grinding of GaN crystals have been reported, which hinders the development of high-efficiency and ultra-precision manufacturing of GaN components. Self-rotating grinding tests of GaN crystals were performed, and the results indicated that abrasive size had a significant influence on the surface morphology and roughness, in comparison with wheel rotational speed and feed speed. As the abrasive size decreased from 18 μm to 1.6 μm, the brittle fracture-dominated surface gradually changed to a full-plastic surface without brittle fractures and cracks. An ultra-smooth surface with a roughness of 1 nm in Sa was acquired using #8000 grinding wheels and a spark-out time of 10 min, which indicated that the machining technology of “grinding instead of polishing” of GaN crystals was achieved in this work. The plastic deformation mechanism of GaN crystals induced by ultra-precision machining was investigated using a cross-sectional TEM method and MD simulation, and both experimental and simulation results indicated that the plastic deformation involved in the scratching process was caused by the formation of polycrystalline nanocrystals, high-angle lattice misorientations, and close-to-atomic-scale defects, including stacking faults, dislocations and serious lattice distortions, along with a small amount of amorphous and phase transitions. There was an obvious delamination phenomenon in the plastic deformation zone. This research enhances the understanding of the deformation and damage mechanisms of GaN crystals involved in the ultra-precision machining process and is of significance for achieving the high-efficiency and high-accuracy manufacturing of GaN components.
104 citations
TL;DR: In this article , a comprehensive review and critical assessment of the existing understanding of electrostatic atomization MQL is provided, which can be used by scientists to gain insights into the action mechanism, theoretical basis, machining performance, and development direction of this technology.
Abstract: Metal cutting fluids (MCFs) under flood conditions do not meet the urgent needs of reducing carbon emission. Biolubricant-based minimum quantity lubrication (MQL) is an effective alternative to flood lubrication. However, pneumatic atomization MQL has poor atomization properties, which is detrimental to occupational health. Therefore, electrostatic atomization MQL requires preliminary exploratory studies. However, systematic reviews are lacking in terms of capturing the current research status and development direction of this technology. This study aims to provide a comprehensive review and critical assessment of the existing understanding of electrostatic atomization MQL. This research can be used by scientists to gain insights into the action mechanism, theoretical basis, machining performance, and development direction of this technology. First, the critical equipment, eco-friendly atomization media (biolubricants), and empowering mechanisms of electrostatic atomization MQL are presented. Second, the advanced lubrication and heat transfer mechanisms of biolubricants are revealed by quantitatively comparing MQL with MCF-based wet machining. Third, the distinctive wetting and infiltration mechanisms of electrostatic atomization MQL, combined with its unique empowering mechanism and atomization method, are compared with those of pneumatic atomization MQL. Previous experiments have shown that electrostatic atomization MQL can reduce tool wear by 42.4% in metal cutting and improve the machined surface R a by 47% compared with pneumatic atomization MQL. Finally, future development directions, including the improvement of the coordination parameters and equipment integration aspects, are proposed.
102 citations
TL;DR: In this paper , an attempt has been made to create curvilinear grooved micro textures on the rear surface of double helical micro end mill with diameter of about 800 μm by electrical discharge machining (EDM) method for lowering specific milling energy and forces.
92 citations
TL;DR: In this paper, an attempt has been made to create curvilinear grooved micro textures on the rear surface of double helical micro end mill with diameter of about 800μm by electrical discharge machining (EDM) method for lowering specific milling energy and forces.
92 citations
TL;DR: In this article , a comprehensive quantitative assessment of tribological characteristics based on force, tool wear, chip, and surface integrity in titanium alloy and nickel alloy machining was performed and the machining mechanisms under lubrication of non-toxic carbon group nano-enhancers were investigated.
89 citations
TL;DR: In this article , an ultrasonic vibration plate device enabling the longitudinal full-wave and transverse half-wave (L2T1) vibration mode for UVAG was proposed, and the characteristics of coupled vibration in different directions were analyzed on the basis of apparent elastic method and finite element method.
TL;DR: A theoretical basis and roadmap to further study or build MVCMFD-MTs using information from the machined surface texture is provided, and current challenges and potential research directions in nowadays intelligent manufacturing are discussed.
TL;DR: In this paper , a review of non-degradable and degradable metallic implant biomaterials such as stainless steel (SS), titanium (Ti), cobalt (Co)-based, nickel-titanium (NiTi), and magnesium (Mg)-based alloys is presented.
Abstract: There is a tremendous increase in the demand for converting biomaterials into high-quality industrially manufactured human body parts, also known as medical implants. Drug delivery systems, bone plates, screws, cranial, and dental devices are the popular examples of these implants - the potential alternatives for human life survival. However, the processing techniques of an engineered implant largely determine its preciseness, surface characteristics, and interactive ability with the adjacent tissue(s) in a particular biological environment. Moreover, the high cost-effective manufacturing of an implant under tight tolerances remains a challenge. In this regard, several subtractive or additive manufacturing techniques are employed to manufacture patient-specific implants, depending primarily on the required biocompatibility, bioactivity, surface integrity, and fatigue strength. The present paper reviews numerous non-degradable and degradable metallic implant biomaterials such as stainless steel (SS), titanium (Ti)-based, cobalt (Co)-based, nickel-titanium (NiTi), and magnesium (Mg)-based alloys, followed by their processing via traditional turning, drilling, and milling including the high-speed multi-axis CNC machining, and non-traditional abrasive water jet machining (AWJM), laser beam machining (LBM), ultrasonic machining (USM), and electric discharge machining (EDM) types of subtractive manufacturing techniques. However, the review further funnels down its primary focus on Mg, NiTi, and Ti-based alloys on the basis of the increasing trend of their implant applications in the last decade due to some of their outstanding properties. In the recent years, the incorporation of cryogenic coolant-assisted traditional subtraction of biomaterials has gained researchers' attention due to its sustainability, environment-friendly nature, performance, and superior biocompatible and functional outcomes fitting for medical applications. However, some of the latest studies reported that the medical implant manufacturing requirements could be more remarkably met using the non-traditional subtractive manufacturing approaches. Altogether, cryogenic machining among the traditional routes and EDM among the non-traditional means along with their variants, were identified as some of the most effective subtractive manufacturing techniques for achieving the dimensionally accurate and biocompatible metallic medical implants with significantly modified surfaces.
TL;DR: In this article , the effects of the laser power density on grinding force, stress distribution, material damage mechanism, subsurface damage depth, and abrasive wear were systematically studied, and the results demonstrated that dislocations, stacking faults, hexagonal-to-cubic phase transition, and amorphous transition were generated during both traditional grinding and laser assisted grinding processes.
TL;DR: In this paper , a novel study, applying ultrasonic vibration along with MQL and LCO2, is proposed to enhance the machinability of Ti-6Al-4V.
TL;DR: In this article , the authors present a comprehensive state-of-the-art review on the machinability of AMed titanium alloys fabricated by various AM techniques, in the light of investigations carried out to understand the cutting forces, surface finish and tool wear when machining/micro-machining AMed Ti.
TL;DR: In this paper , an iterative design methodology for improving the stiffness of laser powder bed fusion (LPBF) components is proposed, which is applied in a case study for finishing thin-walled bent ducts and a comparison for surface quality between stiffened and non-stiffened ducts.
TL;DR: In this paper , a predictive model for the LAG process was established, which has taken the combined effects of temperature-dependent mechanical properties of the material, statuses of grit-material micro interaction, and stochastic shapes and random distributions of abrasive grits into consideration.
TL;DR: In this paper , the machinability characteristics when milling novel material, Cu-B-CrC composites using Al/TiN coated carbide tools was examined. And the dominant effect of reinforcement ratio (Cu, B, CrC) was found to increase the surface roughness, tool wear, chip morphology and cutting temperatures.
Abstract: Ceramics-based composites are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. This makes composites completely different and paves the way for new applications that requires the utmost properties. Machining of such composites is of great importance to finalize the fabrication process with improved part quality; however, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine the machinability characteristics when milling novel material, Cu–B–CrC composites using Al/TiN coated carbide tools. Further, the influence of machining parameters along with the different weight ratios of the powders amounts used to fabricate the machined reinforced samples on output parameters namely surface roughness, tool wear, chip morphology and cutting temperatures was investigated. One of the key findings of the study is the dominant effect of reinforcement ratio (Cu, B, CrC) on machinability, which showed that 5% additive (2% B, 3% CrC) provides improved properties such as surface roughness, tool wear and cutting temperature. Cutting speed alterations play an important role in the machinability characteristics, i.e., increasing value increases flank wear and cutting temperatures and reduces surface roughness. Increasing feed rate increases the surface roughness meanwhile its effect shows changing behavior on the flank wear and cutting temperatures according to cutting speed and reinforcement ratio.
TL;DR: Wang et al. as mentioned in this paper proposed a framework based on feature normalization, attention mechanism, and deep learning algorithms for tool wear monitoring and multi-step prediction, and the results showed that the proposed model has great advantages in efficiency and robustness compared with other data-driven models.
TL;DR: In this study, the Self Organizing Map tool as a non-supervised Neural Network is used to visualize the data and SOM combinations with vector quantification and projection are used to identify or rank the wear machinability parameters on the new composite filament printed under different FDM conditions.
Abstract: In general, visual clusters are preferred over large data sets; this is an attempt to take advantage of cluster techniques to reduce the mathematical complexity of small data sets. To identify the possibility of implementing the clustering technique in a small dataset, the wear observations of PLA/Cu composite samples printed using the Fused Deposition Model (FDM) is taken into consideration. In this study, the Self Organizing Map (SOM) tool as a non-supervised Neural Network (NN) is used to visualize the data. Here, SOM combinations with vector quantification and projection are used to identify or rank the wear machinability parameters on the new composite filament printed under different FDM conditions. The competitive layer in SOM will classify the given parameters of the wear machine (vectors) at any number of dimensions may be into several groups of layer neurons. The limitation of SOM is map size which cannot exceed 1000 units of training. However, for the small data set under consideration, the extent of these limits will not affect performance. The SOM algorithm developed for the study of wear provides the outlet within the acceptable range. In addition, the linear regression analysis is carried out for the output response to measure the wear characteristics of the machining observation.
TL;DR: In this paper , a Longitudinal-Torsional Ultrasonic Assisted Milling (LTUAM) is introduced for machining of a high strength titanium alloy Ti-6Al-4V.
TL;DR: An improved integrated estimation method is proposed based on the long short-term memory (LSTM) network and particle filter (PF) algorithm to predict the stochastic tool wear values and it can be seen that the availability and sustainability of micro cutting tool have been improved and the prediction accuracy could be increased.
TL;DR: In this article , the authors provide a technology overview of metal additive manufacturing (AM) techniques that can be utilized in a wide range of applications, including constructing electrical machines, and the impact of the material forms on printing speed and quality are studied.
Abstract: Metal additive manufacturing (AM) has been growing remarkably in the past few years. Thanks to the advantages of unmatched flexibility and zero material waste, this clean technology opens the door for new design solutions with greater material efficiency, which are not possible through conventional machining techniques. In this paper, we provide a technology overview of metal AM techniques that can be utilized in a wide range of applications, including constructing electrical machines. Different techniques of metal AM are discussed and compared. Additionally, the impact of the material forms (powder/wire) on printing speed and quality are studied. Based on the industrial and technical literature, this paper provides a comprehensive review of metal AM in the fabrication of electrical machines and their applications. This includes the current state of the art and associated benefits of AM in these applications.
TL;DR: In this article , a 3D finite element modelling (FE) simulation was performed with AdvantEdge software and the prediction models were developed for evaluating the cutting forces and cutting temperature while machining AA2024-T351 alloy under dry, liquid nitrogen (LN2) and carbon dioxide (CO2) conditions.
TL;DR: The limit of applicability of the correlation between the ratio of hardness to elastic modulus (H / E ) of coating systems and their wear resistance has been explored in this article .
Abstract: The limit of applicability of the correlation between the ratio of hardness to elastic modulus ( H / E ) of coating systems and their wear resistance has been explored. Experimental approaches to determine accurate H / E values by nanoindentation are discussed and best practice recommendations summarised. Small-scale tribo-testing has been used to simplify complex wear conditions, and the role of contact severity and damage tolerance studied to determine why and when coating optimisation strategies are effective. Case studies show the importance of relatively low coating elastic modulus in reducing tensile stresses in sliding/abrasive contact. This may be a key factor in why coating design for optimised H / E and resistance to plastic deformation , H 3 / E 2 , can be more effective than aiming for extremely high coating hardness since that is typically accompanied by high coating stiffness. The influence of substrate ductility and load support on the damage tolerance of the coating system in impact tests has been investigated by testing at different contact size. Results show that mechanical and microstructural factors should not be considered in isolation. The role of coating microstructural design and temperature on optimising coating performance in high speed machining is investigated.
TL;DR: In this article , the performance of eco-friendly spray-based approach employing vegetable oils to precision machine nickel based superalloy Inconel 718 was compared with dry machining mode.