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19 pages, 6672 KiB

Open AccessArticle

Experimental Investigation of the Effects of Coolant Temperature on Cutting Tool Wear in the Machining Process

by Osman Şahin, Durmuş Karayel, Mustafa Ali Ertürk, Ergün Nart and Ömer Seçgin

Machines 2024, 12(10), 677; https://doi.org/10.3390/machines12100677 - 27 Sep 2024

Viewed by 1098

In machining processes, the heat generated in the cutting zone varies depending on cutting parameters such as depth of cut, cutting speed and feed rate. On the other hand, in most existing machine tools, the flow rate of the coolant sent to the [...] Read more.

In machining processes, the heat generated in the cutting zone varies depending on cutting parameters such as depth of cut, cutting speed and feed rate. On the other hand, in most existing machine tools, the flow rate of the coolant sent to the cutting zone is constant, and there is no additional cooling system in the tank. Therefore, the temperature of the coolant circulating in the closed circuit in the system is constantly increasing, which negatively affects cutting performance. This study aims to investigate the effect of coolant temperature on tool wear in the machining process and to control the coolant temperature. For this purpose, a comprehensive coolant temperature control system was developed and integrated into the CNC machine tool. Thanks to this system, it was possible to automatically control the temperature of the cutting fluid (coolant) and maintain it within a constant temperature range throughout the cutting process. Thus, experiments were conducted at different temperatures with different cutting parameters and coolant emulsion ratios using the developed system. Since the cutting parameters interact with each other, the Taguchi method was used to observe the effect of each parameter and to determine the optimum cutting parameters. As a result, it was observed that tool wear was reduced, tool life was extended and unnecessary coolant use was prevented, especially at low temperatures. In addition, the amount of coolant used is expected to reduce negative environmental impacts. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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20 pages, 8824 KiB

Open AccessArticle

Punching Accuracy in the Case of Square-Shaped Holes

by Gheorghe Nagîț, Andrei Marius Mihalache, Irina Beșliu-Băncescu, Oana Dodun, Liviu Andrușcă, Adelina Hrițuc, Sergiu Constantin Olaru and Laurențiu Slatineanu

Machines 2024, 12(8), 507; https://doi.org/10.3390/machines12080507 - 27 Jul 2024

Viewed by 1061

Abstract

Currently, some parts made from workpieces in the form of sheets or strips are obtained by applying piercing processes. In the research whose results are presented in the article, square-shaped holes were made to evaluate the piercing accuracy of the surfaces generated by [...] Read more.

Currently, some parts made from workpieces in the form of sheets or strips are obtained by applying piercing processes. In the research whose results are presented in the article, square-shaped holes were made to evaluate the piercing accuracy of the surfaces generated by piercing in sheets of three different metal materials (carbon steel 1.033, aluminum alloy AlMg3, and stainless steel X5CrNi18-10) with different thicknesses. Apart from the nature of the material, the thickness of the sheet, the size of the clearance between the puncher and the die, and the average speed of the puncher were considered as input factors in the piercing process. The output parameters tracked were the size of the side of the square-shaped hole and the height of the burr generated by the cut. The experimental results were mathematically processed using special software, obtaining empirical mathematical models that highlight the influence of the input factors considered on the deviation of the side size of the square-shaped hole and the burr height. The analysis of the results showed that the intended size of the square hole side exerts the strongest influence on the piercing accuracy. The factor with the most significant influence on the height of the burr is the clearance between the puncher and the die. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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21 pages, 7029 KiB

Open AccessArticle

Influence of Machine Tool Operating Conditions on the Resulting Circularity and Positioning Accuracy

by Matej Sarvas, Michal Holub, Tomas Marek, Jan Prochazka, Frantisek Bradac and Petr Blecha

Machines 2024, 12(5), 352; https://doi.org/10.3390/machines12050352 - 20 May 2024

Cited by 2 | Viewed by 1609

Abstract

The operating conditions of the production process significantly influence the resulting dimensional and form accuracy of the workpiece. The operating conditions include the position of the workpiece location, with internal and external heat sources influenced not only by the machine location but also [...] Read more.

The operating conditions of the production process significantly influence the resulting dimensional and form accuracy of the workpiece. The operating conditions include the position of the workpiece location, with internal and external heat sources influenced not only by the machine location but also by its operation. In addition, there are the cutting conditions and the feed rate requirements of CNC machine tools. These changes, such as workpiece position, feed rates, and machine heat load, are further reflected in the ability of the machine to run at the position required and interpolate within the given tolerances of circularity. For the accuracy and repeatability of positioning, the machine was set up according to ISO 230-2 and for the circular interpolation tests according to ISO 230-4. The obtained results show the importance of attention to the appropriate setting of the operating conditions of the production process, where the knowledge of the geometric accuracy of the CNC machine tool in its working space can systematically increase the manufacturing accuracy itself or be another tool suitable for predicting the dimensional and form accuracy of workpieces. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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31 pages, 66581 KiB

Open AccessEditor’s ChoiceArticle

Influence of Tool Inclination and Effective Cutting Speed on Roughness Parameters of Machined Shaped Surfaces

by Ján Varga, Michal Demko, Ľuboš Kaščák, Peter Ižol, Marek Vrabeľ and Jozef Brindza

Machines 2024, 12(5), 318; https://doi.org/10.3390/machines12050318 - 5 May 2024

Cited by 3 | Viewed by 2241

Abstract

Free-form surfaces in the automotive or aviation industry where the future shape of the product will contain complex surfaces raises the question of how to achieve the necessary shape of the required quality in the milling process. One of the methods of their [...] Read more.

Free-form surfaces in the automotive or aviation industry where the future shape of the product will contain complex surfaces raises the question of how to achieve the necessary shape of the required quality in the milling process. One of the methods of their production is the use of 5-axis milling, in which it is necessary to consider not only the input data of the process itself, but also the methodology for evaluating the desired results. Correctly answered questions can thus facilitate the choice of the inclination of the tool when machining parts of the surfaces defined in the experiment. The primary goal of the paper was to monitor the influence of tool inclination on the quality of the machined surface and effective cutting speed by evaluating surface roughness and surface topography. The experiment was designed to show the effect of different tool positions while the feed per tooth f_z for the finishing operation remained constant. The best result in terms of surface quality was achieved with a tool inclination of 15° in the cutting process. The most unfavorable result was obtained with a tool axis inclination of zero degrees due to unfavorable cutting conditions. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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11 pages, 1784 KiB

Open AccessArticle

Influence of Laser Texturing and Coating on the Tribological Properties of the Tool Steels Properties

by Jana Moravčíková, Roman Moravčík, Martin Sahul and Martin Necpal

Machines 2024, 12(5), 311; https://doi.org/10.3390/machines12050311 - 2 May 2024

Cited by 3 | Viewed by 1366

Abstract

The article is aimed at identifying the influence of laser texturing and subsequent coating with a hard, wear-resistant coating AlCrSiN (nACRo^®) on selected tribological properties of the analyzed tool steels for cold work, produced by conventional and powder metallurgy. The substrate [...] Read more.

The article is aimed at identifying the influence of laser texturing and subsequent coating with a hard, wear-resistant coating AlCrSiN (nACRo^®) on selected tribological properties of the analyzed tool steels for cold work, produced by conventional and powder metallurgy. The substrate from each steel was heat treated to achieve optimal properties regarding the chemical composition and the method of production of the material. Böhler K100 and K390 Microclean^® steels were used. These are highly alloyed tool steels used for various types of tools intended for cold work. The obtained results show that the coefficient of friction is increased by coating, but the wear rate is lower compared to the samples which were only textured. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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12 pages, 5577 KiB

Open AccessArticle

The Influence of the Setup on the Result of Measuring the Roundness of an Anuloid Surface

by Augustín Görög and Marcel Kuruc

Machines 2024, 12(4), 258; https://doi.org/10.3390/machines12040258 - 12 Apr 2024

Viewed by 1536

Abstract

In engineering practice, anuloid surfaces are produced that are subject to strict requirements in terms of accuracy (e.g., in the bearing industry). Roundness is also often measured. The accuracy of the roundness measurement does not only depend on the accuracy of a particular [...] Read more.

In engineering practice, anuloid surfaces are produced that are subject to strict requirements in terms of accuracy (e.g., in the bearing industry). Roundness is also often measured. The accuracy of the roundness measurement does not only depend on the accuracy of a particular metrological system. The setting of the component on the measuring device can also have a significant influence on the accuracy of the measurement. The axis of the measured surface must be perpendicular to the section in which the roundness is measured. Tilting the measured surface causes a systematic measurement error, which depends on the size of the tilt angle and the parameters of the measured surface. This study presents mathematical relations for the calculation of this error when measuring roundness on an anuloid surface. Mathematical relations for the internal and external surfaces formed by the inner and outer parts of the anuloid are derived herein. There is also a theoretical analysis of the influence of inclination and the parameters of the measured surface on the size of this error. Theoretically calculated values were compared with practically measured values of roundness. The error had a negative effect on the accuracy of the roundness measurement. It affected the roundness value, the second harmonic component, and also the roundness profile itself. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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19 pages, 10347 KiB

Open AccessArticle

Evaluation of Suitability of High-Speed Drag Finishing Machine Prototype Utilization for Workpiece Modification

by Marek Vozár, Boris Pätoprstý, Tomáš Vopát, Róbert Straka, František Jurina and Michal Šajgalík

Machines 2024, 12(4), 251; https://doi.org/10.3390/machines12040251 - 10 Apr 2024

Viewed by 1146

Abstract

The purpose of the experimental results evaluated in this paper is to verify the viability of using a prototype drag finishing machine for the modification of machined workpieces. The workpieces used in the experiments had a cylindrical shape and were manufactured by turning. [...] Read more.

The purpose of the experimental results evaluated in this paper is to verify the viability of using a prototype drag finishing machine for the modification of machined workpieces. The workpieces used in the experiments had a cylindrical shape and were manufactured by turning. Three different workpiece materials were tested, and three workpieces for each material were machined with different cutting parameters. Multiple aspects of the drag-finishing process influence were kept track of—surface roughness, dimensional accuracy, and edge burr shape change. The parameters of the drag finishing were kept constant for all workpieces, and the development of each aforementioned observed aspect was recorded. The workpieces were periodically removed from the process and measured using a coordinate measuring machine with a touch probe, a surface roughness measuring machine, and an optical microscope. Based on the gathered data, it can be concluded that the usage of a prototype drag finishing machine designed primarily for cemented carbide tool microgeometry modification is viable for workpiece finishing as well. The parameters of the drag-finishing process need to be adjusted depending on the workpiece material and initial surface roughness. Additionally, the medium used for the drag finishing should be considered with respect to the desired output quality of the workpiece. Experimental work shows that having one multi-purpose machine for precise modification of wide range of materials and shapes can be an effective approach from the standpoint of economy and productivity when it comes to small numbers of workpieces requiring surface finishing. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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25 pages, 13022 KiB

Open AccessArticle

Design and Optimization of Production Line Layout Using Material Flows

by Michal Bučko, Lucie Krejčí, Ivo Hlavatý and Jiří Lorenčík

Machines 2024, 12(3), 189; https://doi.org/10.3390/machines12030189 - 14 Mar 2024

Cited by 4 | Viewed by 4378

Abstract

Businesses are constantly trying to improve their production by looking for bottlenecks to improve their market position. The introduction and innovation of automated production lines is necessary for both labor shortages and productivity and quality reasons. A combination of precision, fluidity, and speed, [...] Read more.

Businesses are constantly trying to improve their production by looking for bottlenecks to improve their market position. The introduction and innovation of automated production lines is necessary for both labor shortages and productivity and quality reasons. A combination of precision, fluidity, and speed, that is the basic definition of a production line. With the advent of new technologies, production lines have also begun to continuously speed up and innovate. Innovation is the subject of this paper, where the problem of designing a completely new layout for a new production line in the food industry has been addressed. The aim of this paper was to create a design for the optimal layout of the production line in preselected production areas. Optimal use of the space allocated for production is very important for every company today. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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14 pages, 7366 KiB

Open AccessArticle

The Selection of Cutting Speed to Prevent Deterioration of the Surface in Internal Turning of C45 Steel by Small-Diameter Boring Bars

by Tomáš Vopát, Marcel Kuruc, Boris Pätoprstý, Marek Vozár, František Jurina, Barbora Bočáková, Jozef Peterka, Augustín Görög and Róbert Straka

Machines 2024, 12(1), 68; https://doi.org/10.3390/machines12010068 - 17 Jan 2024

Cited by 2 | Viewed by 1892

Abstract

The turning of small-diameter deep holes is usually critical when the process of machining is unstable and the use of a special boring bar is often necessary. This paper is focused on the influence of cutting speed with a combination of cutting conditions [...] Read more.

The turning of small-diameter deep holes is usually critical when the process of machining is unstable and the use of a special boring bar is often necessary. This paper is focused on the influence of cutting speed with a combination of cutting conditions such as feed and tool overhang on chatter marks, surface roughness and roundness of machined holes. In the experiment, two types of tool material for indexable boring bars were used, namely cemented carbide and steel. These are a group of boring bars used for the internal turning of holes of small diameters with indexable cutting inserts. Monolithic carbide boring bars are already used for internal turning of holes of even smaller diameters. Uncoated turning inserts made of cermet were used. The cutting tests were performed on the DMG CTX alpha 500 turning center. In the case of the steel boring bar, decreasing the cutting speed really led to an increase in the quality of the surface roughness and reduced the formation of chatter marks and large chatter marks. The cemented carbide boring bar also followed a similar trend, but it should be noted that the overall effect was not so great. This means that increasing the cutting speed makes the cutting process less stable and, vice versa, lower values of cutting speed reduce the formation of chatter marks and the related deterioration of the surface quality. The occurrence of chatter is directly related to the increase in the surface roughness parameters Ra and Rz of the machined surface. It can be stated that the dependence of roundness deviations on cutting speed values has a similar character to the results of the measured surface roughness values. Therefore, if the cutting speed is increased, it will make the cutting process less stable; this is also indirectly reflected in larger roundness deviations. However, it is necessary to state that this phenomenon can be observed in turning holes with small diameters using the steel boring bar, where the unstable cutting conditions materialized in the form of chatter marks. Full article

(This article belongs to the Special Issue Precision Manufacturing and Machine Tools)

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