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Textured insert for improved heat extraction in combination with high-pressure cooling in turning of superalloys
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-0895-3303
2017 (English)Licentiate 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.

Place, publisher, year, edition, pages
Trollhättan: University West , 2017. , 90 p.
Series
Licentiate Thesis: University West, 19
Keyword [en]
Alloy 718; High-pressure coolant; Heat dissipation, Textured insert; Tungsten carbide, Tool life, Tool wear
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-11738ISBN: 978-91-87531-63-7 (print)ISBN: 978-91-87531-62-0 (electronic)OAI: oai:DiVA.org:hv-11738DiVA: diva2:1147489
Presentation
2017-10-12, F315, University West, Trollhättan, 13:00 (English)
Supervisors
Available from: 2017-10-06 Created: 2017-10-06 Last updated: 2017-10-06Bibliographically approved
List of papers
1. Next Generation Insert for Forced Coolant Application in Machining of Inconel 718
Open this publication in new window or tab >>Next Generation Insert for Forced Coolant Application in Machining of Inconel 718
2016 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 836-837, 340-347 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2016
Keyword
Tool wear, Heat dissipation, Inconel 718, Turning, Forced Coolant Application
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-8767 (URN)10.4028/www.scientific.net/MSF.836-837.340 (DOI)2-s2.0-84958074091 (Scopus ID)
Conference
12th International Conference on High Speed Machining, HSM 2015; Nanjing; China; 18 October 2015 through 20 October 2015
Available from: 2015-12-07 Created: 2015-12-07 Last updated: 2017-10-06Bibliographically approved
2. Investigation of Modified Cutting Insert with Forced Coolant Application in Machining of Alloy 718
Open this publication in new window or tab >>Investigation of Modified Cutting Insert with Forced Coolant Application in Machining of Alloy 718
2016 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 42, 481-486 p.Article in journal (Refereed) Published
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.

Keyword
Turning, Alloy 718, Modified cutting insert, Tool wear, Secondary shear zone, Forced coolant application
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-9245 (URN)10.1016/j.procir.2016.02.236 (DOI)2-s2.0-84966621725 (Scopus ID)
Conference
18th CIRP Conference on Electro Physical and Chemical Machining (ISEM XVIII)
Available from: 2016-03-18 Created: 2016-03-18 Last updated: 2017-10-06Bibliographically approved
3. EDS Analysis of Flank Wear and Surface Integrity in Machining of Alloy 718 with Forced Coolant Application
Open this publication in new window or tab >>EDS Analysis of Flank Wear and Surface Integrity in Machining of Alloy 718 with Forced Coolant Application
Show others...
2016 (Swedish)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 45, 271-274 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
EDS; Heat zone; Surface roughness; Residues; Facing; Forced coolant application; Residual stress
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-10031 (URN)10.1016/j.procir.2016.02.144 (DOI)2-s2.0-84978639847 (Scopus ID)
Conference
3rd CIRP Conference on Surface Integrity,
Available from: 2016-10-21 Created: 2016-10-21 Last updated: 2017-10-06Bibliographically approved
4. Characterization of tool wear when machining alloy 718 with high-pressure cooling using conventional and surface-modified WC-Co tools
Open this publication in new window or tab >>Characterization of tool wear when machining alloy 718 with high-pressure cooling using conventional and surface-modified WC-Co tools
Show others...
2017 (English)In: Journal of Superhard Materials, ISSN 1063-4576, Vol. 39, no 3, 178-185 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Allerton Press, 2017
Keyword
superalloy; high pressure jet assisted machining; tool modification; wear characterization
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11562 (URN)10.3103/S1063457617030054 (DOI)000404329700005 ()
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2017-10-06Bibliographically approved

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