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  • 1.
    Hoier, P.
    et al.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology,GothenburgSweden.
    Klement, Uta
    Chalmers University of Technology, Department of Materials and Manufacturing Technology,GothenburgSweden.
    Tamil Alagan, Nageswaran
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Wretland, A.
    KN Aerospace Engine Systems AB,Trollhättan,Sweden.
    Characterization of tool wear when machining alloy 718 with high-pressure cooling using conventional and surface-modified WC-Co tools2017In: Journal of Superhard Materials, ISSN 1063-4576, Vol. 39, no 3, p. 178-185Article in journal (Refereed)
    Abstract [en]

    Coolant supplied by high pressure into the cutting zone has shown the lower thermal loads on the tool when machining difficult-to-cut materials as the Alloy 718. In this study, we investigate how the combination of high-pressure cooling and tool-surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant-tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by similar to 12%. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45% for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivity of metal cutting processes.

  • 2.
    Hoier, Philipp
    et al.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology, Gothenburg, Sweden.
    Klement, Uta
    Chalmers University of Technology, Department of Materials and Manufacturing Technology, Gothenburg, Sweden.
    Tamil Alagan, Nageswaran
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Characterization of tool wear when machining Alloy 718 with high pressure cooling using conventional and surface-modified WC-Co tools2016In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Coolant supplied by high pressure into the cutting zone has shown to lower thermal loads on the tool when machining difficult-to-cut materials as Alloy 718. In this study, we investigate how the combination of high pressure cooling and tool-surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant-tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by ~ 12%. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45% for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivityof metal cutting processes.

  • 3.
    Hoier, Philipp
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science,Gothenburg, Sweden.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science,Gothenburg, Sweden.
    Tamil Alagan, Nageswaran
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Flank wear characteristics of WC-Co tools when turning Alloy 718 with high-pressure coolant supply2017In: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 30, no Supplement C, p. 116-123Article in journal (Refereed)
    Abstract [en]

    In the present study, the tool wear mechanisms of uncoated cemented tungsten carbide (WC-Co) tools during machining Alloy 718 with high-pressure coolant supply are investigated. Worn flank faces are analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). With increasing spiral cutting length, larger areas on the tool surface are subjected to erosion of Co-binder by the coolant jet impact. Moreover, the amount and morphology of workpiece-precipitates adhered on worn flank surfaces are influenced significantly by the extent of flank wear land (due to increasing spiral cutting length). The reasons for the obtained results are addressed with respect to the underlying mechanisms. Possible implications for the tool wear behavior are discussed.

  • 4.
    Jäger, Henrik
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Swerea-KIMAB AB, 164 40, Stockholm, Sweden.
    Tamil Alagan, Nageswaran
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Holmberg, Jonas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Swerea-IVF AB, 431 22, Mölndal, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Vretland, Anders
    GKN Aerospace Engine Systems AB, 461 81, Trollhättan, Sweden.
    EDS Analysis of Flank Wear and Surface Integrity in Machining of Alloy 718 with Forced Coolant Application2016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 45, p. 271-274Article in journal (Refereed)
    Abstract [en]

    There has been extensive research on forced coolant application, usually known as high pressure coolant, in machining heat resistant super alloys. This technology has shown to improve the tool life, chip segmentation, surface integrity and reduce the temperature in the cutting zone. A number of studies have been done on hydraulic parameters of the coolant. This study has been focused on residues on the flank face of the insert and residual stress on the workpiece surface generated by regular and modified cutting inserts. To identify any residual elements, analysis were done by energy dispersive X-ray spectrometer, EDS, on regular as well as modified inserts in combination with forced coolant application on both rake and flank face. The investigations have shown that the temperature gradient in the insert has changed between the regular and modified cutting inserts and that the tool wear and surface roughness is significantly affected by the modified cutting tool.

  • 5.
    Tamil Alagan, Nageswaran
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Enhanced heat transfer and tool wear in high-pressure coolant assisted turning of alloy 7182019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heat generated in a machining process is a common and critical obstacle faced in today's manufacturing industries. The heat generated in the cutting zone has adirect negative influence on the tool life, which, in turn contributes to increasing the manufacturing costs. Especially in the machining of Heat Resistant Superalloys, HRSA, this is a very limiting factor. HRSA are capable of retaining their mechanical strength and hardness at elevated temperatures. This property is advantageous for applications such as aero-engines, but also a disadvantage, since it also lowers the machinability significantly.This work is an attempt to improve the heat transfer from the cutting zone, which would lead to an increase in the tool life. To achieve this goal, the effect of cooling the flank face (tertiary shear zone) with high-pressure is studied; furthermore, the cutting tool has been modified to create an improved interface between the high pressure coolant and the tool where high-temperature gradient exists.Three main generations of inserts have been designed and investigated. Firstly, an insert with surface texture features created with the purpose of increasing the available surface area for heat dissipation: First generation, Gen I. Secondly, GenI+, a modified rake design of Gen I, for improved frictional conditions on the tool-chip contact. Thirdly, Gen II was designed as a further improvement of GenI. Here, several channel features on the rake face were added, reaching out from the contact zone to the near proximity of the cutting edge. This has the purpose of improving access of the coolant closer to the cutting edge.The experiments were conducted in facing operations of Alloy 718 with uncoated round carbide inserts. All experiments were carried out with high-pressure coolant, with a maximum available pressure of 16 MPa on the rake face and 8MPa on the flank face, respectively. The three generations of inserts, Gen I, I+and II, were experimentally evaluated by tool wear analysis in comparison with a regular insert. The results shows that the tool life increased significantly for the Gen I insert, compared to catastrophic failure of the regular insert at the same conditions. Regarding the Gen II insert, an increase in tool life by approximately30-40 percent, compared to Gen I inserts was observed. XRegarding the coolant-boiling phenomenon, results revealed the existence in form of dark region (Ca precipitate) below the flank wear land. The location and size of the coolant-boiling region is interrelated between flank wear, cutting zone temperature, coolant pressure and vapour pressure of the coolant at the investigated coolant pressure levels. The coolant applied at a pressure lower than the vapour pressure of the coolant itself will cause the "Leidenfrost effect" to appear that will effectively act as a coolant barrier region. However, most importantly, this effect led to the observation of a new wear mechanism present "Cavitation Wear". This type of wear appears in the form of erosion pits on the flank surface of the insert and it is observed for flank pressure conditions of 4and 8 MPa. It is a new phenomenon in tool wear to be seen on uncoated WC cutting tools during machining operations with high-pressure coolant.

  • 6.
    Tamil Alagan, Nageswaran
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Textured insert for improved heat extraction in combination with high-pressure cooling in turning of superalloys2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heat generated in a machining process is a common and critical obstacle faced in today's machining industries. The heat generated in the cutting zone has a direct negative influence on the tool life which, in turn contributes to increase the manufacturing costs. Especially, in machining of Heat Resistant Super Alloys, HRSA this is a very limiting factor. HRSA are capable of retaining their mechanical strength and hardness at elevated temperatures. This property is advantageous in the application in e.g. aero-engines but also a disadvantage, since it also lowers the machinability significantly. This work is an attempt to improve the heat transfer from the cutting zone, which would lead to an increase in the tool life. To achieve this goal, the cutting tool has been modified to create an improved interface between the coolant and tool in the high-temperature areas. Two generations of inserts have been designed and investigated. Firstly, an insert with surface texture features has been created with the purpose of increasing the available surface area for heat dissipation: First generation, Gen I. Secondly, a GenII was designed as a further improvement of Gen I. Here, several channel features on the rake face were added, reaching out from the contact zone to the near proximity of the cutting edge. This with the purpose of improving access of the coolant closer to the cutting edge. The experiments were conducted in facing operations of Alloy 718 with uncoated round carbide inserts. All experiments were carried out with high-pressure coolant assistance, with a pressure of 16 MPa on the rake face and 8 MPa on the flankface, respectively.The two generations of inserts, Gen I and Gen II, were experimentally evaluated by tool wear analysis in comparison with a regular insert. The results shows that the tool life increased significantly for the Gen I insert, compared to a catastrophic failure of the regular insert at the same conditions. Regarding the Gen II insert,an increase in tool life by approximately 30 to 40 percent compared to Gen I insert was observed.

  • 7.
    Tamil Alagan, Nageswaran
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Hoier, Philipp
    Chalmers University of Technology, Department of Industrial and Materials Science, SE-412 96 Gothenburg, Sweden.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, SE-412 96 Gothenburg, Sweden.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, SE-461 81 Trollhättan, Sweden.
    Influence of Surface Features for Increased Heat Dissipation on Tool Wear2018In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, no 5, article id E664Article in journal (Refereed)
    Abstract [en]

    The critical problems faced during the machining process of heat resistant superalloys, (HRSA), is the concentration of heat in the cutting zone and the difficulty in dissipating it. The concentrated heat in the cutting zone has a negative influence on the tool life and surface quality of the machined surface, which in turn, contributes to higher manufacturing costs. This paper investigates improved heat dissipation from the cutting zone on the tool wear through surface features on the cutting tools. Firstly, the objective was to increase the available surface area in high temperature regions of the cutting tool. Secondly, multiple surface features were fabricated for the purpose of acting as channels in the rake face to create better access for the coolant to the proximity of the cutting edge. The purpose was thereby to improve the cooling of the cutting edge itself, which exhibits the highest temperature during machining. These modified inserts were experimentally investigated in face turning of Alloy 718 with high-pressure coolant. Overall results exhibited that surface featured inserts decreased flank wear, abrasion of the flank face, cutting edge deterioration and crater wear probably due to better heat dissipation from the cutting zone.

  • 8.
    Tamil Alagan, Nageswaran
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, 461 81, Sweden.
    Investigation of Modified Cutting Insert with Forced Coolant Application in Machining of Alloy 7182016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 42, p. 481-486Article in journal (Refereed)
    Abstract [en]

    Abstract In the last decades machining methods have witnessed an advancement in both cutting tools and coolant/lubrication, sometimes in combination with high pressure jet. The aim of this work is to investigate a modified cutting insert with forced coolant application, FCA, how it influences the tool-chip contact in the secondary shear zone and how it affects the tool wear when turning Alloy 718. During the machining process the main and frequent problems are heat generation and friction in the cutting zone, which has a direct impact on the cutting tool life. High pressure jet cooling have headwayed the cutting technology for the last five decades, showing an improvment of tool life, reduced temperature in the cutting zone and better surface integrity of the workpiece. These developments have practically enhanced the capability and quality in machining of superalloys. This paper is an advancement of the previous work, increasing surface area of the insert, with a additional channel design to improve the coolant reachability in the tool-chip contact area on the rake face. The influence in tool wear has been investigated. Through a set of experiments, a channel design insert with forced coolant application, has shown about 24-33% decrease in tool wear compared to only a textured insert. Hybrid inserts with its cooling and channel features have even widened the operational cutting region with significantly less tool wear.

  • 9.
    Tamil Alagan, Nageswaran
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Next Generation Insert for Forced Coolant Application in Machining of Inconel 7182016In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 836-837, p. 340-347Article in journal (Refereed)
    Abstract [en]

    Machining technology has undergone an extensive evolution throughout the last decades in its capability to machine hard-to-cut material. This paper will discuss about the next generation insert with cooling feature coupled with forced coolant in machining Inconel 718. The geometry of the insert was changed in a way which has enlarged the surface area approximately 12% compared to regular insert named as nusselt insert. The idea applied in “nusselt insert” was the relation of increase in surface area to heat dissipation. Forced coolant application has become a way to improve existing metal cutting concepts and improve their current material removal rates without any need for a reengineered machining process. Experiments conducted on the inserts is that the first experiment of its kind in machining technology together with forced coolant and tested in four different inserts. The primary focus of the work was the investigation of the relation between the heat dissipation with an increase in surface area/mass ratio in the cutting interface based on its influence on tool wear. The experimental results showed the nusselt insert have better ability for heat dissipation which has led to significant reduce in tool wear and successfully facing Inconel 718 at vc 105 m/min, f 0.3 mm/rev and ap 1 mm where the regular insert had a catastrophic failure at vc 90 m/min, f 0.1 mm/rev and ap 1 mm. Nusselt insert has shown to increase MRR significantly compared to regular insert.

  • 10.
    Tamil Alagan, Nageswaran
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Hoier, Philipp
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Zeman, Pavel
    Department of Production Machines and Equipment, Faculty of Mechanica lEngineering, Center of Advanced AerospaceTechnology, CzechTechnical University in Prague, Czech Republic.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Swede.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Wretland, Anders
    GKN Aerospace Engine Systems AB,Trollhättan, Sweden.
    Effects of high pressure cooling in the flank and rake faces of WC tool on the tool wear mechanism and process conditions in turning of alloy 7182019In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 434-435, article id 102922Article in journal (Refereed)
    Abstract [en]

    The exceptional properties of Heat Resistant Super Alloys (HRSA) justify the search for advanced technologiesthat can improve the capability of machining these materials. One such advanced technology is the applicationof a coolant at high pressure while machining, a strategic solution known for at least six decades. The aim is toachieve extended tool life, better chip control and improved surface finish. Another aim is to control the temperature in the workpiece/tool interface targeting for optimum cutting conditions. In most of the existing applications with high-pressure coolant media, the nozzles are positioned on the rake face side of the insert andthey are directed towards the cutting edge (the high-temperature area). The coolant is applied at high-pressureto improve the penetration of the cooling media along the cutting edge in the interface between the insert andworkpiece material (chip) as well as to increase chip breakability. However, the corresponding infusion ofcoolant media in the interface between the flank face of the insert and the work material (tertiary shear zone) hasbeen previously only scarcely addressed, as is the combined effect of coolant applications on rake and clearancesides of the insert. The present work addresses the influence of different pressure conditions in (flank: 0, 4 and8 MPa; rake: 8 and 16 MPa) on maximum flank wear, flank wear area, tool wear mechanism, and overall processperformance. Round uncoated inserts are used in a set of face turning experiments, conducted on the widely usedHRSA "Alloy 718" and run in two condition tests with respect to cutting speed (45 (low) and 90 (high) m/min).The results show that an increase in rake pressure from 8 to 16 MPa has certainly a positive impact on tool life.Furthermore, at higher vc of 90 m/min, cutting edge deterioration: due to an extensive abrasion and crack in thewear zone were the dominant wear mechanism. Nevertheless, the increase in coolant pressure condition to16 MPa reduced the amount of abrasion on the tool compared to 8 MPa. At the lower cutting speed, no crack orplastic deformation or extensive abrasion were found. When using 8 MPa pressure of coolant media on the flank,the wear was reduced by 20% compared to flood cooling conditions. Application of high-pressure cooling on theflank face has a positive effect on tool life and overall machining performance of Alloy 718.

  • 11.
    Tamil Alagan, Nageswaran
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Zeman, Pavel
    Czech Technical University in Prague, Research Center of Manufacturing Technology, Prague, Czech Republic.
    Hoier, Philipp
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Investigation of micro-textured cutting tools used for face turning of alloy 718 with high-pressure cooling2019In: Journal of manufacturing processes, ISSN 1526-6125, Vol. 37, p. 606-616Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand to improve the service life of cutting tools during machining of heat resistant superalloys (HRSA). Various studies showed that textured cutting tools improved the tribological properties and reduced cutting forces, temperature, and tool wear. Surface texturing can be seen as a futuristic design to improve the performance of the cutting tool and to increase productivity. However, only limited research has been conducted in machining superalloys with textured inserts and high-pressure coolant. In this work, three different micro texture designs on both rake and flank face are investigated in combination with high-pressure coolant in machining Alloy 718. Due to better tool life predictability, carbide cutting tools are used in machining components made from superalloys. However, the disadvantage is that machining can only be done at lower cutting speed/feed rate/depth of cut with high tool wear rates. The experimental investigation using different tool wear analysis methods showed that the combination of a cylindrical dimple on the rake and the square pyramid texture on the flank surface improved the wear resistance of the tool. An increase in tool life of about 30% was achieved as compared with a regular insert for the investigated cutting conditions. Different levels of adhering workpiece material were observed on the rake face of textured tools. Furthermore, the chip backside showed imprints from the tool textures. The tool textures on the rake face have influenced the tool-chip friction conditions during cutting.

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