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Evaluation of an intermittent sliding test for reproducing work material transfer in milling operations
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Tribomaterial)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Tribomaterial)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. (Tribomaterial)
Primateria AB, Uppsala.
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2012 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 52, 153-160 p.Article in journal (Refereed) Published
Abstract [en]

TiN coated HSS test cylinders from an intermittent sliding test were compared with TiN coated HSS milling inserts from a single insert milling test. A 20NiCrMo2 case hardening steel was used as counter material and work material in the two tests. HSS test cylinders, coated with AlCrN, TiAlN and Al2O3, were also tested in the intermittent sliding test and evaluated with regard to material adhesion. Two distinctly different tribofilms were formed on test cylinders as well as on cutting inserts. One consisting of Mn, Si, Al and O and one consisting of Fe, Mn, Cr, Si and O. The transferred material was similar in appearance and composition, both when comparing the two test methods and when comparing the different tool coatings.

Place, publisher, year, edition, pages
2012. Vol. 52, 153-160 p.
Keyword [en]
Transfer, Coating, Chip, Sliding
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Tribo Materials; Engineering Science with specialization in Materials Science
Identifiers
URN: urn:nbn:se:uu:diva-167051DOI: 10.1016/j.triboint.2012.03.015ISI: 000304798900015OAI: oai:DiVA.org:uu-167051DiVA: diva2:480617
Available from: 2012-01-19 Created: 2012-01-19 Last updated: 2017-12-08Bibliographically approved
In thesis
1. On Transfer of Work Material to Tools
Open this publication in new window or tab >>On Transfer of Work Material to Tools
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bulk forming and cutting are widely used to shape metals in industrial production. Bulk forming is characterized by large strains, extensive plastic deformation and large surface expansions. Cutting is characterized by high speeds, high pressures and high temperatures. The prevailing conditions during these processes lead to transfer of work material to tools. In bulk forming this is a significant problem. The transferred work material is hardened and becomes harder than the work material, causing galling. This leads to high friction and high forming forces, bad surface finish of the formed products and significant difficulties to produce complicated geometries. In cutting, transfer of work material can be desired for protection of the tool surface. However, the transfer film has to be of the correct type to provide a stable and predictive behaviour during operation.

In this thesis the influence from tool material and surface treatment on work material transfer has been studied for both applications, with the use of simplified laboratory test methods followed by extensive surface studies. Both the tendency to, appearance of and chemical composition of work material transfer is evaluated. The results are compared with real industrial examples, to ensure that the correct mechanisms are mimicked.

In forming, the problems arise when poor lubrication prevails, due to high forming forces or large surface expansions. The transfer of work material can then be avoided with the use of a galling resistant coating, offering low adhesion. However, the coating has to be as smooth as possible, to avoid activation of the work material and subsequent transfer.

In cutting, the desired transfer film can be obtained by choosing the correct cutting parameters. The geometry and material of the fabricated component is often predetermined, setting the general cutting conditions, but the cutting speed influences the formation of the transfer film. Too low speed or too high speed leads to an unstable cutting process and poor surface finish of the piece. The speed intervals for each mechanism are partly determined by the tool material and thus by the tool coating.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Uppsaliensis, 2012. 68 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 894
Keyword
Tribology, Friction, Forming, Cutting, Galling, Material transfer, Tribological coatings, Surface finish, Micro mechanisms, Aluminium
National Category
Engineering and Technology
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-165828 (URN)978-91-554-8261-9 (ISBN)
Public defence
2012-03-02, Häggsalen, Lägerhyddsvägen 1, Uppsala, 10:15 (Swedish)
Supervisors
Available from: 2012-02-10 Created: 2012-01-10 Last updated: 2013-04-08
2. Tribology at the Cutting Edge: A Study of Material Transfer and Damage Mechanisms in Metal Cutting
Open this publication in new window or tab >>Tribology at the Cutting Edge: A Study of Material Transfer and Damage Mechanisms in Metal Cutting
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The vision of this thesis is to improve the metal cutting process, with emphasis on the cutting tool, to enable stable and economical industrial production while using expensive tools such as hobs. The aim is to increase the tribological understanding of the mechanisms operating at a cutting edge and of how these can be controlled using different tool parameters. Such understanding will facilitate the development and implementation of future, tribologically designed, cutting tools.

Common wear and failure mechanisms in gear hobbing have been identified and focused studies of the material transferred to the tool, in both metal cutting operations and in simplified tribological tests, have been conducted. Interactions between residual stresses in the tool coating and the shape of the cutting edge have also been studied.

It was concluded that tool failure is often initiated via small defects in the coated tool system, and it is necessary to eliminate, or minimize, these defects in order to manufacture more reliable and efficient gear cutting tools. Furthermore, the geometry of a cutting edge should be optimized with the residual stress state in the coating, in mind. The interaction between a compressive stress and the geometry of the cutting edge will affect the stress state at the cutting edge and thus affect the practical toughness and the wear resistance of the coating in that area.

An intermittent sliding contact test is presented and shown to be of high relevance for studying the interaction between the tool rake face and the chip in milling. It was also demonstrated that material transfer, that can have large effects on the cutting performance, commences already after very short contact times. The nature of the transfer may differ in different areas on the tool. It may include glassy layers, with accumulations of specific elements from the workpiece, and transfer of steel in more or less oxidized form. Both tool coating material, its surface roughness, and the relative speed between the tool surface and the chip, may influence the extent to which the different transfer will occur.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 77 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 988
Keyword
Tribology, Metal cutting, Gear hobbing, Wear, Coating, Residual stress, Material transfer, Steel
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Tribo Materials
Identifiers
urn:nbn:se:uu:diva-183186 (URN)978-91-554-8514-6 (ISBN)
Public defence
2012-12-07, 2005, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (Swedish)
Supervisors
Available from: 2012-11-16 Created: 2012-10-23 Last updated: 2013-01-23Bibliographically approved

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Gerth, JuliaHeinrichs, JannicaNyberg, HaraldWiklund, Urban

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