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Influence of Surface Features for Increased Heat Dissipation on Tool Wear
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-0895-3303
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0003-0976-9820
Chalmers University of Technology, Department of Industrial and Materials Science, SE-412 96 Gothenburg, Sweden.
Chalmers University of Technology, Department of Industrial and Materials Science, SE-412 96 Gothenburg, Sweden.
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2018 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 11, no 5, article id E664Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
2018. Vol. 11, no 5, article id E664
Keywords [en]
Alloy 718, carbide insert, high-pressure coolant, machining, textured inserts, tool-chip contact area
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-12274DOI: 10.3390/ma11050664ISI: 000434711700014PubMedID: 29693579Scopus ID: 2-s2.0-85046275282OAI: oai:DiVA.org:hv-12274DiVA, id: diva2:1202779
Funder
Knowledge FoundationRegion Västra Götaland
Note

Funders: EDS

Available from: 2018-04-30 Created: 2018-04-30 Last updated: 2019-11-18Bibliographically approved
In thesis
1. Enhanced heat transfer and tool wear in high-pressure coolant assisted turning of alloy 718
Open this publication in new window or tab >>Enhanced heat transfer and tool wear in high-pressure coolant assisted turning of alloy 718
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Förbättrad värmeavledning och verktygsslitage vid högtryckskyld svarvning av legering 718
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.

Place, publisher, year, edition, pages
Trollhättan: University West, 2019. p. 118
Series
PhD Thesis: University West ; 31
Keywords
Alloy 718; Cavitation; Coolant-boiling; High-pressure coolant; Heat dissipation, Leidenfrost effect; Textured insert; Tungsten carbide; Tool life; Tool wear
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-14663 (URN)978-91-88847-42-3 (ISBN)978-91-88847-41-6 (ISBN)
Public defence
2019-11-22, Albertssalen, 10:00 (English)
Opponent
Supervisors
Available from: 2019-10-30 Created: 2019-10-30 Last updated: 2019-10-30Bibliographically approved

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Tamil Alagan, NageswaranBeno, Tomas

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