Special Issue "Advances and Trends in Non-conventional, Abrasive and Precision Machining 2021"

A special issue of Machines (ISSN 2075-1702). This special issue belongs to the section "Advanced Manufacturing".

Deadline for manuscript submissions: 15 November 2021.

Special Issue Editors

Prof. Dr. Mariusz Deja
E-Mail Website
Guest Editor
Gdańsk University of Technology, Faculty of Mechanical Engineering, Department of Manufacturing and Production Engineering, Poland
Interests: abrasive processes; lapping; grinding with lapping kinematics; rapid manufacturing and tooling; algorithms for computer-aided process planning
Special Issues and Collections in MDPI journals
Dr. Angelos P. Markopoulos
E-Mail Website
Guest Editor
National Technical University of Athens, School of Mechanical Engineering, Laboratory of Manufacturing Technology, Greece
Interests: precision and ultraprecision manufacturing processes; micromachining; nonconventional processes in macro; micro- and nanoscale; modeling
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The modern highly competitive industrial environment demands machining and production processes resulting in exceptional quality and precision. The general trend to design and manufacture more complicated mechanical components, along with the rapidly moving forward material science, raise the need to incorporate and develop new machining techniques in the manufacturing process. Nonconventional machining processes differ from conventional ones, as they utilize alternative types of energy, such as thermal, electrical, and chemical, to form or to remove material. Commonly, the energy source has high power density, while the process features prodigious accuracy, and the capability to produce and handle demanding shapes and geometries. Examples of nonconventional machining processes are electrical discharge machining (EDM), electrochemical machining (ECM), laser processing, and laser-assisted machining. Abrasive processes like grinding, lapping, polishing, and superfinishing are constantly developing and allow for obtaining a fine surface finish along with high efficiency.   

There is an increased scientific and commercial interest in in-depth understanding, and further development of the aforementioned nonconventional and precision machining processes. Research is moving forward through experimental studies, as well in the field of modeling and simulation, exploiting the increased available computational power. Multiphysics and multidisciplinary and multiscale modeling are powerful tools in the effort to optimize existing nonconventional precision machining processes, as well to develop novel ones. As their wider use by the industry swiftly grows, research has to be focused on them, not only due to the academic and scientific interest, but also for the possible financial gain.

This Special Issue aims at attracting researchers to present recent advances and technologies in the aforementioned fields, indicating the future trends for nonconventional precision machining processes.

Prof. Dr. Mariusz Deja
Prof. Dr. Angelos P. Markopoulos
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. Machines is an international peer-reviewed open access monthly 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

  • Laser processing/laser-assisted machining
  • High-density power machining
  • Electrodischarge machining
  • Electrochemical machining
  • Abrasive processes
  • Lapping/polishing/superfinishing
  • Ultrasonic machining
  • Water jet machining/abrasive water jet machining
  • Burnishing
  • Other nonconventional machining
  • Precision machining
  • Micro- and nanomachining
  • Machine tools
  • Modeling and simulation
  • Surface quality and integrity
  • Manufacturing systems
  • Nanomaterials

Published Papers (7 papers)

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Research

Article
On-Machine Measurement and Error Compensation for 6061 Aluminum Alloy Hexagonal Punch Using a Turn-Milling Machine
Machines 2021, 9(9), 180; https://doi.org/10.3390/machines9090180 - 25 Aug 2021
Viewed by 199
Abstract
For machining parts with complex shapes, consisting of computer numerical control (CNC) machine tools, different CNC machine tools will be used according to the machining method. If the workpiece is removed for off-machine measurement after machining, when the size is incorrect, it will [...] Read more.
For machining parts with complex shapes, consisting of computer numerical control (CNC) machine tools, different CNC machine tools will be used according to the machining method. If the workpiece is removed for off-machine measurement after machining, when the size is incorrect, it will need to be returned to the CNC machine tool for secondary machining. In this case, the workpiece surface quality and machining accuracy will be affected, which is very time-consuming. On-machine measurement and complex machine center is a key to solve this problem. In the recent researches that the touch probe was integrated on three or five axis machine for error compensation and shape construction based on on-machine measurement, but turning-milling machine was rare. In addition, the most types of parts were thin-walled parts or thin web parts. In this study, a contact measurement system is integrated into a CNC combined turning-milling machine for on-machine measuring. Macro-programming is used to design the machining path of A6061-T6 aluminum alloy hexagonal punch, and the action of probe measurement is added to the machining path. As the measured data exceed the tolerance range, the calculated data are fed back to the controller for machining improvement by compensation. The finished hexagonal punch is measured in a 3D coordinate measuring machine and the error is compared. The experimental results show that the contact probe needs to be corrected before machining, and the size of the corrected workpiece can reach the tolerance range of ±0.01 mm. The size error of rough machining is larger than that of fined machining, and the size error of rough machining will increase with the length of the workpiece. Full article
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Article
Study on the Importance of a Slicer Selection for the 3D Printing Process Parameters via the Investigation of G-Code Readings
Machines 2021, 9(8), 163; https://doi.org/10.3390/machines9080163 - 11 Aug 2021
Viewed by 373
Abstract
The work deals with the investigation of the variation of the selected 3D printing process properties that originate from the choice of a slicer. Specifically, the main aim of the present study was to assess the induced changes of the kinematic and geometric [...] Read more.
The work deals with the investigation of the variation of the selected 3D printing process properties that originate from the choice of a slicer. Specifically, the main aim of the present study was to assess the induced changes of the kinematic and geometric properties considered by the slicer for the printing process making use of the G-code readings. The paper provides adequate definitions and formulas required to characterize the slicer’s configuration. Next, the selected cases of the process parameters’ changes were studied, primarily taking into account varying layer height and infill. The authors performed a detailed analysis regarding the geometric implications at the mesoscale due to the slicer’s settings. Appropriate modifications of the slicer’s properties were also proposed and verified, making it possible to match the geometric and kinematic characteristics of the printed part. Full article
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Article
Evaluation of the Ability to Accurately Produce Angular Details by 3D Printing of Plastic Parts
Machines 2021, 9(8), 150; https://doi.org/10.3390/machines9080150 - 29 Jul 2021
Viewed by 366
Abstract
3D printing is a process that has become widely used in recent years, allowing the production of parts with relatively complicated shapes from metallic and non-metallic materials. In some cases, it is challenging to evaluate the ability of 3D printers to make fine [...] Read more.
3D printing is a process that has become widely used in recent years, allowing the production of parts with relatively complicated shapes from metallic and non-metallic materials. In some cases, it is challenging to evaluate the ability of 3D printers to make fine details of parts. For such an assessment, the printing of samples showing intersections of surfaces with low angle values was considered. An experimental plan was designed and materialized to highlight the influence of different factors, such as the thickness of the deposited material layer, the printing speed, the cooling and filling conditions of the 3D-printed part, and the thickness of the sample. Samples using areas in the form of isosceles triangles with constant height or bases with the same length, respectively, were used. The mathematical processing of the experimental results allowed the determination of empirical mathematical models of the power-function type. It allowed the detection of both the direction of actions and the intensity of the influence exerted by the input factors. It is concluded that the strongest influence on the printer’s ability to produce fine detail, from the point of view addressed in the paper, is exerted by the vertex angle, whose reduction leads to a decrease in printing accuracy. Full article
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Article
Simulation of the Circulating Motion of the Working Medium and Metal Removal during Multi-Energy Processing under the Action of Vibration and Centrifugal Forces
Machines 2021, 9(6), 118; https://doi.org/10.3390/machines9060118 - 17 Jun 2021
Viewed by 401
Abstract
The rotational motion of the medium granules under the influence of an impeller installed in the bottom of a cylindrical reservoir is considered. The dependencies of the circulation velocity of the abrasive granules, as well as the dependence of the pressure in the [...] Read more.
The rotational motion of the medium granules under the influence of an impeller installed in the bottom of a cylindrical reservoir is considered. The dependencies of the circulation velocity of the abrasive granules, as well as the dependence of the pressure in the circulation flow of the granules on the radius of the vibrating machine cylindrical reservoir for different speeds of the impeller rotation are obtained. Furthermore, the velocities of the abrasive granules at various distances from the center of the cylindrical reservoir of the vibrating machine have been determined. The amplitudes of the tangential and radial components of the velocity of movement of pseudo-gas from abrasive granules are obtained. The total pressure on the surface of the processed part and the average velocity of the abrasive granules colliding with it are determined. The graphical dependencies of the integral metal removal on the amplitude and frequency of oscillations of the walls of the vibrating machine reservoir are given for various values of the angular velocities of the impeller rotation. Full article
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Article
Development of a New Finishing Process Combining a Fixed Abrasive Polishing with Magnetic Abrasive Finishing Process
Machines 2021, 9(4), 81; https://doi.org/10.3390/machines9040081 - 12 Apr 2021
Viewed by 659
Abstract
High quality, highly efficient finishing processes are required for finishing difficult-to-machine materials. Magnetic abrasive finishing (MAF) process is a finishing method that can obtain a high accuracy surface using fine magnetic particles and abrasive particles, but has poor finishing efficiency. On the contrary, [...] Read more.
High quality, highly efficient finishing processes are required for finishing difficult-to-machine materials. Magnetic abrasive finishing (MAF) process is a finishing method that can obtain a high accuracy surface using fine magnetic particles and abrasive particles, but has poor finishing efficiency. On the contrary, fixed abrasive polishing (FAP) is a polishing process can obtain high material removal efficiency but often cannot provide a high-quality surface at the nano-scale. Therefore, this work proposes a new finishing process, which combines the magnetic abrasive finishing process and the fixed abrasive polishing process (MAF-FAP). To verify the proposed methodology, a finishing device was developed and finishing experiments on alumina ceramic plates were performed. Furthermore, the mechanism of the MAF-FAP process was investigated. In addition, the influence of process parameters on finishing characteristics is discussed. According to the experimental results, this process can achieve high-efficiency finishing of brittle hard materials (alumina ceramics) and can obtain nano-scale surfaces. The surface roughness of the alumina ceramic plate is improved from 202.11 nm Ra to 3.67 nm Ra within 30 min. Full article
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Article
Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy
Machines 2021, 9(4), 75; https://doi.org/10.3390/machines9040075 - 30 Mar 2021
Viewed by 849
Abstract
Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance [...] Read more.
Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance to fatigue and corrosion. Usually, in order to achieve sufficiently high surface quality, process parameters, such as cutting speed and feed, are regulated or special types of cutting tools are used. In the present work, an alternative strategy for slot milling is adopted, namely, trochoidal milling, which employs a more complex trajectory for the cutting tool. Two series of experiments were initially conducted with traditional and trochoidal milling under various feed and cutting speed values in order to evaluate the capabilities of trochoidal milling. The findings showed a clear difference between the two milling strategies, and it was shown that the trochoidal milling strategy is able to provide superior surface quality when the appropriate process parameters are also chosen. Finally, the effect of the depth of cut, coolant and trochoidal stepover on surface roughness during trochoidal milling was also investigated, and it was found that lower depths of cut, the use of coolant and low values of trochoidal stepover can lead to a considerable decrease in surface roughness. Full article
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Article
Adaptive Cutting Control for Roadheaders Based on Performance Optimization
Machines 2021, 9(3), 46; https://doi.org/10.3390/machines9030046 - 24 Feb 2021
Cited by 2 | Viewed by 523
Abstract
Aiming at addressing the problems of high specific energy consumption for cutting and slow response to the change of hardness in the control of existing mining roadheaders, an adaptive variable speed cutting control method based on cutting performance optimization is proposed by analyzing [...] Read more.
Aiming at addressing the problems of high specific energy consumption for cutting and slow response to the change of hardness in the control of existing mining roadheaders, an adaptive variable speed cutting control method based on cutting performance optimization is proposed by analyzing the working principle of roadheaders. Firstly, cylinder pressure and motor current are invoked as the criteria to judge load changes. Particle swarm optimization is utilized to optimize the cutting parameters under different impedance. Then, the relation between cutting speed, motor current and cylinder pressure is established by using fuzzy neural network to train cutting parameters and identification parameters under different conditions. Finally, the vector control of motor and electro-hydraulic servo valve is used to control the cutting speed. The results show that the cutting unit can adapt to different load signals and always keep the roadheader in the optimal working state. The rotation speed regulation of the cutting head reaches the stable state after 0.05 s, with the overshoot of 1.42%. The swing speed regulation of the cutting head reaches the stable state after 1 s, with the overshoot of 5.3%. Conclusions provide a basis for improving the cutting efficiency and prolonging the working life of the roadheader. Full article
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