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The effect of grinding and polishing procedure of tool steels in sheet metal forming
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.ORCID iD: 0000-0002-1225-0598
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Enineering.
Department of Mechanical Engineering, Technical University of Denmark.
2010 (English)In: ICTPM 2010, 2010, 603-612 p.Conference paper, (Refereed)
Abstract [en]

The surface finish of tools in sheet metal forming has a large influence on the performance of the forming tool. Galling, concern of wear in sheet metal forming, is a severe form of adhesive wear where sheet material is transferred on to the tool surface. By polishing the tools to a fine surface finish, material pick-up has traditionally been reduced, but some surface preparations withstand adhesive wear better. To investigate the effect on galling performance of different surface preparations lubricated tests have been performed using a strip reduction rig. Two different tool materials, Vancron 40 and Vanadis 6 and up to ten different grinding and polishing treatments were tested against AISI 316 stainless steel. The tests showed that an optimum surface preparation might be found at the transition between abrasive and adhesive wear.

Place, publisher, year, edition, pages
2010. 603-612 p.
Keyword [en]
galling, sheet metal forming, wear, sheet surface treatment
National Category
Materials Engineering
Research subject
Materials Engineering
Identifiers
URN: urn:nbn:se:kau:diva-8969OAI: oai:DiVA.org:kau-8969DiVA: diva2:467766
Conference
The 4th International Conference on Tribology in Manufacturing Processes, June 15th 2010, Nice
Available from: 2011-12-19 Created: 2011-12-19 Last updated: 2014-09-04Bibliographically approved
In thesis
1. On tool steel, surface preparation, contact geometry and wear in sheet metal forming
Open this publication in new window or tab >>On tool steel, surface preparation, contact geometry and wear in sheet metal forming
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In sheet metal forming operations the life length of the production equipment islargely dependent on the wear of the tools that are in direct contact with the sheet.One form of adhesive wear where some sheet material gets transferred to the tool, alsoknown as galling, is the most common cause of tool failure. The transferred materialsticks firmly to the tool and will scratch subsequent sheets and increase friction, renderingthem anywhere from aesthetically unsightly to completely ripped apart. Withcareful combination of several parameters the tools production life can be significantlyextended. The surface preparation of the tools has a large influence on the tool life, thesurface has to be smooth and yet not without texture. It was shown in strip reductiontesting that the orientation as well as the depth of the surface texture left by polishinginfluenced the tool life and that a texture perpendicular to the sliding direction was toprefer. The geometry of the forming tool is also a parameter to take into account as itinfluences the tool life not only by changing the contact pressure but also in itself. Ina sliding against flat sheet test rig a lower contact pressure increased the sliding distanceto galling. When two different geometries were compared at the same contactpressure it was found that there was a difference in tool life. As to the tool itself thematerial it’s made of influences the wear rate and tool life. Different tool steels wasinvestigated in sliding wear against metal sheets; Vancron 40 performed better thanVanadis 6 and S290PM performed better than a AISI M2 grade steel.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2011. 47 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2011:64
Keyword
Wear, Galling, sheet metal, deep drawing, Tool steel, surface preparation, Friction
National Category
Materials Engineering
Research subject
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-8883 (URN)978-91-7063-403-1 (ISBN)
Presentation
2012-01-13, 21A342, Karlstads universitet, Karlstad, 09:12 (English)
Opponent
Supervisors
Available from: 2011-12-20 Created: 2011-12-08 Last updated: 2014-09-04Bibliographically approved
2. Adhesive wear testing and modelling of tool steels sliding against sheet metals
Open this publication in new window or tab >>Adhesive wear testing and modelling of tool steels sliding against sheet metals
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Sheet metal forming is a manufacturing method used because of its versatility. Sheets are plastically deformed by a tool to create a product. A tool is expected to last for several 100,000 forming operations and efforts are made to optimize the tools. A common type of wear referred to as galling is the adhesion of sheet material to the tools. This problem has become more prevalent as new high strength sheet materials have been developed at the same time as lubricants have become heavily regulated. This has forced the development of new tool steels with improved resistance to galling. There are many parameters influencing the response to galling. In this work the influence of surface preparation, contact geometry, material selection and lubrication has been investigated. The surface of the forming tools has a large influence on the tools effective life. To refurbish a forming tool is expensive and often requires special shops and hand polishing. The influence on galling of different surface preparations suited for sheet metal forming was investigated using a strip-reduction equipment. The contact conditions of a tool sliding against metal sheets were investigated using FE models. The contact conditions were calculated for a U-bending test and for a sliding-on-flat-surface wear tester. The results were compared to those found in literature. One model incorporated the surface roughness of a sheet as measured by optical profilometry. The strength of the interface between the tool and the sheet material determine if material can be transferred onto the tool. The interface between the tool and adhered sheet material was closely studied using transmission electron microscopy of thin lamellas produced by focused ion beam milling. This showed sheet material adhering to the tool without the formation of an interlayer. Finally, several different combinations of tool steels and sheet materials were tested with regards to their ability to withstand galling.

Abstract [en]

Baksidestext:

Sheet metal forming can be used to produce a wide range of products but the initial costs are high as the forming tools are expensive. Wear of the tools in the form of galling i.e. the adhesion of tiny pieces of sheet material to the tools has become more prevalent as high strength sheet materials have been developed and lubricants have become heavily regulated.

In this work the influence on galling of surface preparation, contact geometry, material selection and lubrication has been investigated. It was found that tool surfaces should be polished as rougher surfaces quickly picked up material that adhered to the tools and subsequently scratched the sheets. The strength of the interface between the tool and the sheet material determine if material can be transferred onto the tool. The interface was studied using bright field transmission electron microscopy and the sheet material was found to adhere to the tool without the formation of an interlayer. The conditions under which galling occurs were studied using a slider on flat surface wear tester and several different material combinations were tested with regards to their galling resistance. The contact conditions of the test equipment were also modeled using FE models to better understand the strains of the materials involved.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2014. 64 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2014:25
Keyword
Adhesive wear
National Category
Materials Engineering
Research subject
Materials Engineering
Identifiers
urn:nbn:se:kau:diva-31793 (URN)978-91-7063-556-4 (ISBN)
Public defence
2014-05-09, 21A342, Eva Erikssonsalen, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2014-05-05 Created: 2014-03-30 Last updated: 2014-05-05Bibliographically approved

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