| 1. |
- Das, Kallol, et al.
(författare)
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Effect of tool wear on quality in drilling of titanium alloy Ti6Al4V, Part II : Microstructure and Microhardness
- 2017
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Ingår i: High Speed Machining. - Warsaw, Poland : De Gruyter Open. - 2299-3975. ; 3:1, s. 11-22
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Tidskriftsartikel (refereegranskat)abstract
- Drilling of Ti6Al4V with worn tools can introduce superficial and easily measured features such as increase of cutting forces, entry and exit burrs and surface quality issues and defects. Such issues were presented in the part I of this paper. In part II, subsurface quality alterations,such as changes of the microstructure and microhardness variation is considered by preparing metallographic sections and measurement, mapping of the depth of grain deformation, and microhardness in these sections. Drastic changes in the microstructure and microhardness were found in sections drilled with drills with large wear lands, particularly in the dry cutting tests. These measurements emphasize the importance of detection of tool wear and ensuring coolant flow in drilling of holes in titanium components.
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| 2. |
- Eynian, Mahdi, 1980-, et al.
(författare)
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Effect of tool wear on quality in drilling of titanium alloy Ti6Al4V, Part I : Cutting Forces, Burr Formation, Surface Quality and Defects
- 2017
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Ingår i: High speed machining. - Warsaw, Poland : De Gruyter Open. - 2299-3975. ; 3:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Titanium's Ti6Al4V, alloy is an important material with a wide range of applications in the aerospace industry.Due to its high strength, machining this material for desired quality at high material removal rate is challenging and may lead to high tool wear rate. As a result,this material may be machined with worn tools and the effects of tool wear on machining quality need to be investigated.In this experimental paper, it is shown how drills of various wear levels affect the cutting forces, surface quality and burr formation. Furthermore, it is shown that high cutting forces and high plastic deformation, along with high temperatures that arise in cutting with worn tools may lead to initiation of microscopic cracks in the workpiece material in proximity of the drilling zone.
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| 3. |
- Hoier, Philipp, 1988, et al.
(författare)
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Characterization of tool wear when machining Alloy 718 with high-pressure cooling using conventional and surface-modified WC–Co tools
- 2017
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Ingår i: Journal of Superhard Materials. - : Allerton Press. - 1063-4576 .- 1934-9408. ; 39:3, s. 178-185
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Tidskriftsartikel (refereegranskat)abstract
- 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 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 ~ 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.
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| 4. |
- Hoier, Philipp, 1988, et al.
(författare)
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Flank wear characteristics of WC-Co tools when turning Alloy 718 with high-pressure coolant supply
- 2017
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Ingår i: Journal of Manufacturing Processes. - Dearbord, Mich. : Society of Manufacturing Engineers, North American Manufacturing Research Institution. - 1526-6125 .- 2212-4616. ; 30:Supplement C, s. 116-123
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Tamil Alagan, Nageswaran, 1990-
(författare)
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Textured insert for improved heat extraction in combination with high-pressure cooling in turning of superalloys
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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