E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Special Issue "Machining—Recent Advances, Applications and Challenges"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 31 December 2018

Special Issue Editors

Guest Editor
Prof. Dr. Luis Norberto López de Lacalle

High Performance Manufacturing Group, Department of Mechanical Engineering, University of the Basque Country UPV/EHU, E-48013 Bilbao, Spain
Website | E-Mail
Interests: manufacturing; machine tools; gears; mechanical engineering; trasmissions
Guest Editor
Dr. Gorka Urbicain

Dept Mechanical Eng., University of the Basque Country
E-Mail
Interests: machine tools; modelling; chatter, dynamics

Special Issue Information

Dear Colleagues,

In 1907, the American engineer, F.W. Taylor, exposed the basis and fundamentals of modern machining concepts, such as the relationship between tool life and cutting speed, the economic optimization of the machining processes, and modern management of industrial companies, which along with previous developments of new grades of high-alloyed steels (HSS) for the production of cutting tools, promoted a rapid evolution of machining processes. In the 20th century, continuous advances happened one after the other, related to the invention of sintered carbide tools, coatings, the introduction of CNC in machine-tools, multitasking and multiprocess concepts, etc. At the start of this century, machining remains the key operation to achieve high productivity and precision for high-added value parts in several sectors. Continous research is performed and new ideas are constantly considered.

This Special Issue is open to new advances in machining aspects, involving:

  • High performance operations for difficult-to-cut alloys, wrought and cast materials, light alloys, ceramics, etc.
  • Cutting tools, grades, substrates and coatings. Wear damage.
  • New applications of machining in high-added value components, for aeronautics, automotive, windmill, energy, and other key sectors.
  • Heat in metal cutting: Heat sources, accuracy in machining, prediction and measurements of temperatures in the cutting zone.
  • New approaches in the tribology of the cutting process.
  • Advanced cooling in machining: Minimum quantity of lubricant, dry or cryogenics.
  • Modelling, focused on the reduction of risks, the process outcome, and to maintain surface integrity.
  • Vibration problems in machines: Active and passive/predictive methods, sources, diagnosis and avoidance.
  • Influence of machining in new concepts of machine–tool, and machine static and dynamic behaviors.
  • Machinability of new composites, brittle and emerging materials.
  • Sensor-assisted machining: Sensors and system architecture, intelligent/smart tools.
  • Machining economics and optimization: Advanced methods.
  • Assisted machining processes by high-pressure, laser, US and others.
  • Micromachining, challenges and applications.
  • Introduction of new analytics and decision making into machining programming.

Prof. Dr. Luis Norberto López De Lacalle
Dr. Gorka Urbicain
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access bimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • machining
  • machine-tools
  • cutting tools
  • machinability
  • modelling
  • tribology

Published Papers (17 papers)

View options order results:
result details:
Displaying articles 1-17
Export citation of selected articles as:

Research

Open AccessArticle Theoretical and Experimental Investigation of Surface Topography Generation in Slow Tool Servo Ultra-Precision Machining of Freeform Surfaces
Materials 2018, 11(12), 2566; https://doi.org/10.3390/ma11122566
Received: 21 November 2018 / Revised: 12 December 2018 / Accepted: 14 December 2018 / Published: 17 December 2018
PDF Full-text (13384 KB) | HTML Full-text | XML Full-text
Abstract
Freeform surfaces are featured with superior optical and physical properties and are widely adopted in advanced optical systems. Slow tool servo (STS) ultra-precision machining is an enabling manufacturing technology for fabrication of non-rotationally symmetric surfaces. This work presents a theoretical and experimental study
[...] Read more.
Freeform surfaces are featured with superior optical and physical properties and are widely adopted in advanced optical systems. Slow tool servo (STS) ultra-precision machining is an enabling manufacturing technology for fabrication of non-rotationally symmetric surfaces. This work presents a theoretical and experimental study of surface topography generation in STS machining of freeform surfaces. To achieve the nanometric surface topography, a systematic approach for tool path generation was investigated, including tool path planning, tool geometry selection, and tool radius compensation. The tool radius compensation is performed only in one direction to ensure no high frequency motion is imposed on the non-dynamic axis. The development of the surface generation simulation allows the prediction of the surface topography under various tool and machining variables. Furthermore, it provides an important means for better understanding the surface generation mechanism without the need for costly trial and error tests. Machining and measurement experiments of a sinusoidal grid and microlens array sample validated the proposed tool path generation and demonstrated the effectiveness of the STS machining process to fabricate freeform surfaces with nanometric topography. The measurement results also show a uniform topography distribution over the entire surface and agree well with the simulated results. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Experimental Determination of Residual Stresses Generated by Single Point Incremental Forming of AlSi10Mg Sheets Produced Using SLM Additive Manufacturing Process
Materials 2018, 11(12), 2542; https://doi.org/10.3390/ma11122542
Received: 13 November 2018 / Revised: 8 December 2018 / Accepted: 11 December 2018 / Published: 13 December 2018
PDF Full-text (6215 KB) | HTML Full-text | XML Full-text
Abstract
This paper focuses on investigating the residual stress values associated with a part fabricated by Selective Laser Melting technology (SLM) when this is subjected further to forces on single point incremental forming (SPIF) operation of variable wall angle. The residual stresses induced by
[...] Read more.
This paper focuses on investigating the residual stress values associated with a part fabricated by Selective Laser Melting technology (SLM) when this is subjected further to forces on single point incremental forming (SPIF) operation of variable wall angle. The residual stresses induced by the SLM manufacturing process on the fabricated AlSi10Mg metallic sheets, as well as those produced during their forming SPIF operation were determined by X-ray diffraction (XRD) measurements. Significant residual stress levels of variation, positive or negative, along the metallic sample were observed because of the bending effects induced by the SPIF processes. It is also shown how the wall thickness varies along the additive manufactured SPIFed part as well as the morphology of the melting pools as a function of the deformation depth. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Graphical abstract

Open AccessArticle Drilling Process in γ-TiAl Intermetallic Alloys
Materials 2018, 11(12), 2379; https://doi.org/10.3390/ma11122379
Received: 26 October 2018 / Revised: 16 November 2018 / Accepted: 21 November 2018 / Published: 26 November 2018
PDF Full-text (2161 KB) | HTML Full-text | XML Full-text
Abstract
Gamma titanium aluminides (γ-TiAl) present an excellent behavior under high temperature conditions, being a feasible alternative to nickel-based superalloy components in the aeroengine sector. However, considered as a difficult to cut material, process cutting parameters require special study to guarantee component quality. In
[...] Read more.
Gamma titanium aluminides (γ-TiAl) present an excellent behavior under high temperature conditions, being a feasible alternative to nickel-based superalloy components in the aeroengine sector. However, considered as a difficult to cut material, process cutting parameters require special study to guarantee component quality. In this work, a developed drilling mechanistic model is a useful tool in order to predict drilling force (Fz) and torque (Tc) for optimal drilling conditions. The model is a helping tool to select operational parameters for the material to cut by providing the programmer predicted drilling forces (Fz) and torque (Tc) values. This will allow the avoidance of operational parameters that will cause excessively high force and torque values that could damage quality. The model is validated for three types of Gamma-TiAl alloys. Integral hard metal end-drilling tools and different cutting parameters (feeds and cutting speeds) are tested for three different sized holes for each alloy. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Multi-Objective Optimization for Grinding of AISI D2 Steel with Al2O3 Wheel under MQL
Materials 2018, 11(11), 2269; https://doi.org/10.3390/ma11112269
Received: 26 October 2018 / Revised: 5 November 2018 / Accepted: 7 November 2018 / Published: 13 November 2018
PDF Full-text (4663 KB) | HTML Full-text | XML Full-text
Abstract
In the present study, the machinability indices of surface grinding of AISI D2 steel under dry, flood cooling, and minimum quantity lubrication (MQL) conditions are compared. The comparison was confined within three responses, namely, the surface quality, surface temperature, and normal force. For
[...] Read more.
In the present study, the machinability indices of surface grinding of AISI D2 steel under dry, flood cooling, and minimum quantity lubrication (MQL) conditions are compared. The comparison was confined within three responses, namely, the surface quality, surface temperature, and normal force. For deeper insight, the surface topography of MQL-assisted ground surface was analyzed too. Furthermore, the statistical analysis of variance (ANOVA) was employed to extract the major influencing factors on the above-mentioned responses. Apart from this, the multi-objective optimization by Grey–Taguchi method was performed to suggest the best parameter settings for system-wide optimal performance. The central composite experimental design plan was adopted to orient the inputs wherein the inclusion of MQL flow rate as an input adds addition novelty to this study. The mathematical models were formulated using Response Surface Methodology (RSM). It was found that the developed models are statistically significant, with optimum conditions of depth of cut of 15 µm, table speed of 3 m/min, cutting speed 25 m/min, and MQL flow rate 250 mL/h. It was also found that MQL outperformed the dry as well as wet condition in surface grinding due to its effective penetration ability and improved heat dissipation property. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Fast Analytic Simulation for Multi-Laser Heating of Sheet Metal in GPU
Materials 2018, 11(11), 2078; https://doi.org/10.3390/ma11112078
Received: 3 October 2018 / Revised: 20 October 2018 / Accepted: 21 October 2018 / Published: 24 October 2018
PDF Full-text (10186 KB) | HTML Full-text | XML Full-text
Abstract
Interactive multi-beam laser machining simulation is crucial in the context of tool path planning and optimization of laser machining parameters. Current simulation approaches for heat transfer analysis (1) rely on numerical Finite Element methods (or any of its variants), non-suitable for interactive applications;
[...] Read more.
Interactive multi-beam laser machining simulation is crucial in the context of tool path planning and optimization of laser machining parameters. Current simulation approaches for heat transfer analysis (1) rely on numerical Finite Element methods (or any of its variants), non-suitable for interactive applications; and (2) require the multiple laser beams to be completely synchronized in trajectories, parameters and time frames. To overcome this limitation, this manuscript presents an algorithm for interactive simulation of the transient temperature field on the sheet metal. Contrary to standard numerical methods, our algorithm is based on an analytic solution in the frequency domain, allowing arbitrary time/space discretizations without loss of precision and non-monotonic retrieval of the temperature history. In addition, the method allows complete asynchronous laser beams with independent trajectories, parameters and time frames. Our implementation in a GPU device allows simulations at interactive rates even for a large amount of simultaneous laser beams. The presented method is already integrated into an interactive simulation environment for sheet cutting. Ongoing work addresses thermal stress coupling and laser ablation. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Using the Machine Vision Method to Develop an On-machine Insert Condition Monitoring System for Computer Numerical Control Turning Machine Tools
Materials 2018, 11(10), 1977; https://doi.org/10.3390/ma11101977
Received: 21 August 2018 / Revised: 11 October 2018 / Accepted: 11 October 2018 / Published: 14 October 2018
PDF Full-text (7487 KB) | HTML Full-text | XML Full-text
Abstract
This study uses the machine vision method to develop an on-machine turning tool insert condition monitoring system for tool condition monitoring in the cutting processes of computer numerical control (CNC) machines. The system can identify four external turning tool insert conditions, namely fracture,
[...] Read more.
This study uses the machine vision method to develop an on-machine turning tool insert condition monitoring system for tool condition monitoring in the cutting processes of computer numerical control (CNC) machines. The system can identify four external turning tool insert conditions, namely fracture, built-up edge (BUE), chipping, and flank wear. This study also designs a visual inspection system for the tip of an insert using the surrounding light source and fill-light, which can be mounted on the turning machine tool, to overcome the environmental effect on the captured insert image for subsequent image processing. During image capture, the intensity of the light source changes to ensure that the test insert has appropriate surface and tip features. This study implements outer profile construction, insert status region capture, insert wear region judgment, and calculation to monitor and classify insert conditions. The insert image is then trimmed according to the vertical flank, horizontal blade, and vertical blade lines. The image of the insert-wear region is captured to monitor flank or chipping wear using grayscale value histogram. The amount of wear is calculated using the wear region image as the evaluation index to judge normal wear or over-wear conditions. On-machine insert condition monitoring is tested to confirm that the proposed system can judge insert fracture, BUE, chipping, and wear. The results demonstrate that the standard deviation of the chipping and amount of wear accounts for 0.67% and 0.62%, of the average value, respectively, thus confirming the stability of system operation. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Graphical abstract

Open AccessArticle Comparison of Flank Super Abrasive Machining vs. Flank Milling on Inconel® 718 Surfaces
Materials 2018, 11(9), 1638; https://doi.org/10.3390/ma11091638
Received: 19 July 2018 / Revised: 3 September 2018 / Accepted: 5 September 2018 / Published: 6 September 2018
Cited by 1 | PDF Full-text (5617 KB) | HTML Full-text | XML Full-text
Abstract
Thermoresistant superalloys present many challenges in terms of machinability, which leads to finding new alternatives to conventional manufacturing processes. In order to face this issue, super abrasive machining (SAM) is presented as a solution due to the fact that it combines the advantages
[...] Read more.
Thermoresistant superalloys present many challenges in terms of machinability, which leads to finding new alternatives to conventional manufacturing processes. In order to face this issue, super abrasive machining (SAM) is presented as a solution due to the fact that it combines the advantages of the use of grinding tools with milling feed rates. This technique is commonly used for finishing operations. Nevertheless, this work analyses the feasibility of this technique for roughing operations. In order to verify the adequacy of this new technique as an alternative to conventional process for roughing operations, five slots were performed in Inconel® 718 using flank SAM and flank milling. The results showed that flank SAM implies a suitable and controllable process to improve the manufacture of high added value components made by nickel-based superalloys in terms of roughness, microhardness, white layer, and residual stresses. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Experimental Parametric Model for Adhesion Wear Measurements in the Dry Turning of an AA2024 Alloy
Materials 2018, 11(9), 1598; https://doi.org/10.3390/ma11091598
Received: 2 August 2018 / Revised: 29 August 2018 / Accepted: 30 August 2018 / Published: 3 September 2018
PDF Full-text (9827 KB) | HTML Full-text | XML Full-text
Abstract
Adhesion wear is the main wear mechanism in the dry turning of aluminium alloys. This type of wear produces an adhesion of the machining material on the cutting tool, decreasing the final surface quality of the machining parts and making it more difficult
[...] Read more.
Adhesion wear is the main wear mechanism in the dry turning of aluminium alloys. This type of wear produces an adhesion of the machining material on the cutting tool, decreasing the final surface quality of the machining parts and making it more difficult to maintain industrial tolerances. This work studies the influence of the cutting parameters on the volume of material adhered to the cutting tool surface for dry machining of AA2024 (Al-Cu). For that purpose, a specific methodology based on the automatic image processing method that can obtain the area and the thickness of the adhered material has been designed. This methodology has been verified with the results obtained through 3D analysis techniques and compared with the adhered volume. The results provided experimental parametric models for this wear mechanism. These models are analytic approximations of experimental data. The feed rate mainly results in low cutting speed, while low depths of cut presents a different behaviour due to the low contact pressure. The unstable behaviour of aluminium adhesion on the cutting tool produces a high variability of results. This continuous change introduces variation in the process caused by the continuous change of the cutting tool geometry. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Investigation of Cutting Temperature during Turning Inconel 718 with (Ti,Al)N PVD Coated Cemented Carbide Tools
Materials 2018, 11(8), 1281; https://doi.org/10.3390/ma11081281
Received: 15 May 2018 / Revised: 14 June 2018 / Accepted: 20 July 2018 / Published: 25 July 2018
Cited by 1 | PDF Full-text (5820 KB) | HTML Full-text | XML Full-text
Abstract
Physical Vapor Deposition (PVD) Ti1−xAlxN coated cemented carbide tools are commonly used to cut difficult-to-machine super alloy of Inconel 718. The Al concentration x of Ti1−xAlxN coating can affect the coating microstructure, mechanical
[...] Read more.
Physical Vapor Deposition (PVD) Ti1−xAlxN coated cemented carbide tools are commonly used to cut difficult-to-machine super alloy of Inconel 718. The Al concentration x of Ti1−xAlxN coating can affect the coating microstructure, mechanical and thermo-physical properties of Ti1−xAlxN coating, which affects the cutting temperature in the machining process. Cutting temperature has great influence on the tool life and the machined surface quality. In this study, the influences of PVD (Ti,Al)N coated cemented carbide tools on the cutting temperature were analyzed. Firstly, the microstructures of PVD Ti0.41Al0.59N and Ti0.55Al0.45N coatings were inspected. The increase of Al concentration x enhanced the crystallinity of PVD Ti1−xAlxN coatings without epitaxy growth of TiAlN crystals. Secondly, the mechanical and thermo-physical properties of PVD Ti0.41Al0.59N and Ti0.55Al0.45N coated tools were analyzed. The pinning effects of coating increased with the increasing of Al concentration x, which can decrease the friction coefficient between the PVD Ti1−xAlxN coated cemented carbide tools and the Inconel 718 material. The coating hardness and thermal conductivity of Ti1−xAlxN coatings increased with the increase of Al concentration x. Thirdly, the influences of PVD Ti1−xAlxN coated tools on the cutting temperature in turning Inconel 718 were analyzed by mathematical analysis modelling and Lagrange simulation methods. Compared with the uncoated tools, PVD Ti0.41Al0.59N coated tools decreased the heat generation as well as the tool temperature to reduce the thermal stress generated within the tools. Lastly, the influences of Ti1−xAlxN coatings on surface morphologies of the tool rake faces were analyzed. The conclusions can reveal the influences of PVD Ti1−xAlxN coatings on cutting temperature, which can provide guidance in the proper choice of Al concentration x for PVD Ti1−xAlxN coated tools in turning Inconel 718. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Numerical Simulation and Experimental Investigation of Cold-Rolled Steel Cutting
Materials 2018, 11(7), 1263; https://doi.org/10.3390/ma11071263
Received: 28 May 2018 / Revised: 13 July 2018 / Accepted: 20 July 2018 / Published: 23 July 2018
PDF Full-text (31782 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents results of the investigations on numerical computations and experimental verification concerning the influence of selected parameters of the cutting process on the stress state in bundles of cold-rolled steel sheets being cut using a guillotine. The physical model and, corresponding
[...] Read more.
The paper presents results of the investigations on numerical computations and experimental verification concerning the influence of selected parameters of the cutting process on the stress state in bundles of cold-rolled steel sheets being cut using a guillotine. The physical model and, corresponding to it, the mathematical model of the analysed steel sheet being cut were elaborated. In this work, the relationship between the cutting depth and the values of reduced Huber–Mises stresses as well as the mechanism of sheet separation were presented. The numerical simulations were conducted by means of the finite element method and the computer system LS-DYNA. The results of numerical computations are juxtaposed as graphs, tables, and contour maps of sheet deformation as well as reduced Huber–Mises strains and stresses for selected time instants. The microscopic tests revealed two distinct zones in the fracture areas. The ductile and brittle zones are separated at the depth of ca. 1/3 thickness of the cut steel sheet. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle A Consistent Procedure Using Response Surface Methodology to Identify Stiffness Properties of Connections in Machine Tools
Materials 2018, 11(7), 1220; https://doi.org/10.3390/ma11071220
Received: 30 May 2018 / Revised: 3 July 2018 / Accepted: 11 July 2018 / Published: 16 July 2018
Cited by 1 | PDF Full-text (4208 KB) | HTML Full-text | XML Full-text
Abstract
Accurate finite element models of mechanical systems are fundamental resources to perform structural analyses at the design stage. However, uncertainties in material properties, boundary conditions, or connections give rise to discrepancies between the real and predicted dynamic characteristics. Therefore, it is necessary to
[...] Read more.
Accurate finite element models of mechanical systems are fundamental resources to perform structural analyses at the design stage. However, uncertainties in material properties, boundary conditions, or connections give rise to discrepancies between the real and predicted dynamic characteristics. Therefore, it is necessary to improve these models in order to achieve a better fit. This paper presents a systematic three-step procedure to update the finite element (FE) models of machine tools with numerous uncertainties in connections, which integrates statistical, numerical, and experimental techniques. The first step is the gradual application of fractional factorial designs, followed by an analysis of the variance to determine the significant variables that affect each dynamic response. Then, quadratic response surface meta-models, including only significant terms, which relate the design parameters to the modal responses are obtained. Finally, the values of the updated design variables are identified using the previous regression equations and experimental modal data. This work demonstrates that the integrated procedure gives rise to FE models whose dynamic responses closely agree with the experimental measurements, despite the large number of uncertainties, and at an acceptable computational cost. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Effects of Cutting Edge Microgeometry on Residual Stress in Orthogonal Cutting of Inconel 718 by FEM
Materials 2018, 11(6), 1015; https://doi.org/10.3390/ma11061015
Received: 15 May 2018 / Revised: 12 June 2018 / Accepted: 13 June 2018 / Published: 14 June 2018
PDF Full-text (7417 KB) | HTML Full-text | XML Full-text
Abstract
Service performance of components such as fatigue life are dramatically influenced by the machined surface and subsurface residual stresses. This paper aims at achieving a better understanding of the influence of cutting edge microgeometry on machined surface residual stresses during orthogonal dry cutting
[...] Read more.
Service performance of components such as fatigue life are dramatically influenced by the machined surface and subsurface residual stresses. This paper aims at achieving a better understanding of the influence of cutting edge microgeometry on machined surface residual stresses during orthogonal dry cutting of Inconel 718. Numerical and experimental investigations have been conducted in this research. The cutting edge microgeometry factors of average cutting edge radius S¯, form-factor K, and chamfer were investigated. An increasing trend for the magnitudes of both tensile and compressive residual stresses was observed by using larger S¯ or introducing a chamfer on the cutting edges. The ploughing depth has been predicted based on the stagnation zone. The increase of ploughing depth means that more material was ironed on the workpiece subsurface, which resulted in an increase in the compressive residual stress. The thermal loads were leading factors that affected the surface tensile residual stress. For the unsymmetrical honed cutting edge with K = 2, the friction between tool and workpiece and tensile residual stress tended to be high, while for the unsymmetrical honed cutting edge with K = 0.5, the high ploughing depth led to a higher compressive residual stress. This paper provides guidance for regulating machine-induced residual stress by edge preparation. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle Influence of the Regime of Electropulsing-Assisted Machining on the Plastic Deformation of the Layer Being Cut
Materials 2018, 11(6), 886; https://doi.org/10.3390/ma11060886
Received: 27 April 2018 / Revised: 22 May 2018 / Accepted: 23 May 2018 / Published: 25 May 2018
Cited by 3 | PDF Full-text (629 KB) | HTML Full-text | XML Full-text
Abstract
In this article, the influence of electropulsing on the machinability of steel S235 and aluminium 6060 has been studied during conventional and electropulsing-assisted turning processes. The machinability indices such as chip compression ratio ξ , shear plane angle ϕ and specific cutting energy
[...] Read more.
In this article, the influence of electropulsing on the machinability of steel S235 and aluminium 6060 has been studied during conventional and electropulsing-assisted turning processes. The machinability indices such as chip compression ratio ξ , shear plane angle ϕ and specific cutting energy (SCE) are investigated by using different cutting parameters such as cutting speed, cutting feed and depth of cut during electrically-assisted turning process. The results and analysis of this work indicated that the electrically-assisted turning process improves the machinability of steel S235, whereas the machinability of aluminium 6060 gets worse. Finally, due to electropluses (EPs), the chip compression ratio ξ increases with the increase in cutting speed during turning of aluminium 6060 and the SCE decreases during turning of steel S235. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Graphical abstract

Open AccessArticle ANN Surface Roughness Optimization of AZ61 Magnesium Alloy Finish Turning: Minimum Machining Times at Prime Machining Costs
Materials 2018, 11(5), 808; https://doi.org/10.3390/ma11050808
Received: 5 April 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
Cited by 3 | PDF Full-text (20483 KB) | HTML Full-text | XML Full-text
Abstract
Magnesium alloys are widely used in aerospace vehicles and modern cars, due to their rapid machinability at high cutting speeds. A novel Edgeworth–Pareto optimization of an artificial neural network (ANN) is presented in this paper for surface roughness (Ra) prediction of
[...] Read more.
Magnesium alloys are widely used in aerospace vehicles and modern cars, due to their rapid machinability at high cutting speeds. A novel Edgeworth–Pareto optimization of an artificial neural network (ANN) is presented in this paper for surface roughness (Ra) prediction of one component in computer numerical control (CNC) turning over minimal machining time (Tm) and at prime machining costs (C). An ANN is built in the Matlab programming environment, based on a 4-12-3 multi-layer perceptron (MLP), to predict Ra, Tm, and C, in relation to cutting speed, vc, depth of cut, ap, and feed per revolution, fr. For the first time, a profile of an AZ61 alloy workpiece after finish turning is constructed using an ANN for the range of experimental values vc, ap, and fr. The global minimum length of a three-dimensional estimation vector was defined with the following coordinates: Ra = 0.087 μm, Tm = 0.358 min/cm3, C = $8.2973. Likewise, the corresponding finish-turning parameters were also estimated: cutting speed vc = 250 m/min, cutting depth ap = 1.0 mm, and feed per revolution fr = 0.08 mm/rev. The ANN model achieved a reliable prediction accuracy of ±1.35% for surface roughness. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle The Effect of Weld Reinforcement and Post-Welding Cooling Cycles on Fatigue Strength of Butt-Welded Joints under Cyclic Tensile Loading
Materials 2018, 11(4), 594; https://doi.org/10.3390/ma11040594
Received: 7 March 2018 / Revised: 4 April 2018 / Accepted: 7 April 2018 / Published: 12 April 2018
PDF Full-text (71362 KB) | HTML Full-text | XML Full-text
Abstract
This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the
[...] Read more.
This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the shielded metal arc welding (SMAW) process with welding electrode E6013. The welding reinforcement was 1 mm and 3 mm, respectively; axial fatigue tests were carried out to determine the life and behavior in cracks propagation of the tested welded joints, mechanical characterization tests of properties in welded joints such as microhardness, Charpy impact test and metallographic analysis were carried out. The latter were used as input for the analysis by finite elements which influence the initiation and propagation of cracks and the evaluation of stress intensity factors (SIF). The latter led to obtaining the crack propagation rate and the geometric factor. The tested specimens were analyzed, by taking photographs of the cracks at its beginning in order to make a count of the marks at the origin of the crack. From the results obtained and the marks count, the fatigue crack growth rate and the influence of the cooling media on the life of the welded joint are validated, according to the experimental results. It can be concluded that the welded joints with a higher weld reinforcement have a shorter fatigue life. This is due to the stress concentration that occurs in the vicinity of the weld toe. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Graphical abstract

Open AccessArticle Characteristics of the Arcing Plasma Formation Effect in Spark-Assisted Chemical Engraving of Glass, Based on Machine Vision
Materials 2018, 11(4), 470; https://doi.org/10.3390/ma11040470
Received: 6 February 2018 / Revised: 19 March 2018 / Accepted: 20 March 2018 / Published: 22 March 2018
PDF Full-text (36219 KB) | HTML Full-text | XML Full-text
Abstract
Spark-assisted chemical engraving (SACE) is a non-traditional machining technology that is used to machine electrically non-conducting materials including glass, ceramics, and quartz. The processing accuracy, machining efficiency, and reproducibility are the key factors in the SACE process. In the present study, a machine
[...] Read more.
Spark-assisted chemical engraving (SACE) is a non-traditional machining technology that is used to machine electrically non-conducting materials including glass, ceramics, and quartz. The processing accuracy, machining efficiency, and reproducibility are the key factors in the SACE process. In the present study, a machine vision method is applied to monitor and estimate the status of a SACE-drilled hole in quartz glass. During the machining of quartz glass, the spring-fed tool electrode was pre-pressured on the quartz glass surface to feed the electrode that was in contact with the machining surface of the quartz glass. In situ image acquisition and analysis of the SACE drilling processes were used to analyze the captured image of the state of the spark discharge at the tip and sidewall of the electrode. The results indicated an association between the accumulative size of the SACE-induced spark area and deepness of the hole. The results indicated that the evaluated depths of the SACE-machined holes were a proportional function of the accumulative spark size with a high degree of correlation. The study proposes an innovative computer vision-based method to estimate the deepness and status of SACE-drilled holes in real time. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Figure 1

Open AccessArticle On the Cutting Performance of Segmented Diamond Blades when Dry-Cutting Concrete
Materials 2018, 11(2), 264; https://doi.org/10.3390/ma11020264
Received: 18 January 2018 / Revised: 5 February 2018 / Accepted: 7 February 2018 / Published: 9 February 2018
Cited by 3 | PDF Full-text (5850 KB) | HTML Full-text | XML Full-text
Abstract
The objective of the present study is to analyze and compare the cutting performance of segmented diamond blades when dry-cutting concrete. A cutting criteria is proposed to characterize the wear of the blades by measuring the variation of the external diameter and the
[...] Read more.
The objective of the present study is to analyze and compare the cutting performance of segmented diamond blades when dry-cutting concrete. A cutting criteria is proposed to characterize the wear of the blades by measuring the variation of the external diameter and the weight loss of the blade. The results exhibit the cutting blade SB-A, which has twice the density of diamonds and large contact area, exhibits less wear even though the material removal rate is higher compared with the other two cutting blades. Additionally, the surface topography of the different blades is evaluated to examine the impact of wear depending on the surface profile and the distribution of the diamonds in the blade’s matrix. Large number of diamonds pull-out are found in blades type SB-C, which additionally shows the worst wear resistant capability. As a conclusion, the cutting efficiency of the blade is found to be related to the density of embedded diamonds and the type of the surface profile of the cutting blade after reaching the stop criteria. Full article
(This article belongs to the Special Issue Machining—Recent Advances, Applications and Challenges)
Figures

Graphical abstract

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Author(s): Helena Fernandes and Luis Norberto López de Lacalle
Title:
A consistent procedure using response surface methodology to identify stiffness properties of connections in machine tools

Author(s): Antonio Sánchez Egea and Luis Norberto López de Lacalle
Title:
Enhancement of the surface properties when combining friction stir welding and ball-burnishing application

Author(s):Stephen T Newman
Affiliation:University of Bath, UK

Author(s):Erhan Budak
Affiliation:Sabancı University, Turkey

Author(s): Gorka Urbicain
Title: Experimental study on advanced finisning of gamma-TiAl

Author(s): A. Iglesias*, G. Gonzalez*, J.Munoa* and Z. Dombovari
Title: Optimal design of variable pitch cutters for chatter avoidance in face milling operations
Affiliation: Dynamics & Control Department, IK4-IDEKO, Elgoibar, Basque Country, Spain

Author(s): Batista, Moisés
Proposed work: machining of metal matrix composite materials or about tool wear of aluminium alloys
Affiliation: Universidad de Cadiz, Faculty of Engineering, Cadiz, Spain

Author(s): Jose Luis Cantero Guisandez 
Title:Hybrid composite-metal stacks drilling with different mínimum quantity lubrication leves
Affiliation:University Carlos III de Madrid, Madrid, Spain

Author(s):Jorge Posada
Title:Fast Analytic Simulation for Multi-Laser Heating of Sheet Metal in GPU
Affiliation:
Vicomtech, Spain

 


 
Back to Top