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The effects of bead surface roughness on friction, die pickup, and sheet surface damage in the drawbead test were investigated. Beads of HRC 58 hardness were prepared from centerless-ground rod by circumferential honing to 0.05 μm roughness, followed by finishing with 100, 400, or 600 grit SiC paper in the axial direction. Paraffinic base oils with viscosities of 4.5, 30, and 285 mm2/s were used neat and in conjunction with stearic acid. The effects of bead roughness depended on the nature of metal transfer, especially its distribution and firmness of attachment. The presence of a boundary additive increased, decreased, or had no effect on friction depending on the particular coating and bead finish.

Details of the development of metal transfer and friction were studied by drawing cold-rolled bare, galvannealed, electrogalvanized, and hot-dip galvanized strips with a mineral-oil lubricant of 30 cSt viscosity at 40 C, over a total distance of 2500 mm by three methods. An initial high friction peak was associated with metal transfer to the beads and was largest with pure zinc and smallest with Fe-Zn coatings. Insertion of a new strip disturbed the coating and led to the development of secondary peaks. Long-term trends were governed by the stability of the coating. Stearic acid added to mineral oil delayed stabilization of the coating and increased contact area and thus friction with pure zinc surfaces. The usual practice of reporting average friction values can hide valuable information on lubrication mechanisms and metal transfer.

This study was undertaken to examine the role of tool finish orientation on the drawing of zinc-coated steel sheets. Beads of average roughnesses of 0.1 μm and 0.2 μm, finished parallel to and perpendicular to sliding, were used in the drawbead test. Lubrication was provided by unblended base oils of 4.5, 30, and 285 mm2/s @ 40°C, used neat and with a boundary additive, 1% stearic acid. Three types of coated sheet (galvannealed, electrogalvanized, and hot-dip galvanized) were compared to bare AKDQ steel sheet. Results show that lubricant viscosity had the greatest effect on friction, while bead finish orientation and coating type influenced the nature of metal transfer and the galling of the strip. Mixed-film lubrication dominated with the medium and heavy lubricants, here contact area and friction were reduced with increasing lubricant viscosity.

Drawbead simulation (DBS) tests were conducted on materials representative of cold-rolled, galvannealed, electrogalvanized, and hot-dip galvanized sheets used in the automotive industry, with paraffin wax, microcrystalline wax, stearic acid, tristearin, and Na-stearate solid films. Lubrication behavior did not follow a constant coefficient of friction model; friction declined with increasing sheet thickness but generally less than dictated by a constant shear stress model. Friction was affected also by the surface topography and hardness (deformability) of the sheet surface and was lower for surfaces of lower roughness and hardness. Microscopic valleys in the contact area of galvannealed and, particularly, electrogalvanized sheets indicated the development of micro-plastohydrodynamic lubrication. The effects of speed were attributable mostly to the strain-rate sensitivity of steel with a minor contribution by the lubricant film.

The ultimate aim of applied research is the generation of knowledge relevant to production processes. A vital first step in acquiring such knowledge is the choice of experimental methodology. There are innumerable test methods developed specially for exploring the tribology of sheet metalworking; the purpose of this paper is to examine the major classes of test methods for their applicability to the most important sheet metalworking processes. A distinction is made between simulation and bench tests. When viewed critically, many so-called simulation tests are, in fact, bench tests. They may well be suitable for generating basic information but, for transfer of results to applications, require a knowledge of the lubrication mechanisms active in both test and process.

The growing use of coated sheets, aluminum alloy sheets, and coated dies has led to a veritable explosion of publications in the tribology of sheet metalworking. The present paper aims to assess the state of knowledge and provide a starting point for researchers and practitioners alike. Results of potentially valuable work are often difficult to interpret because vital pieces of information are missing. Recommendations are now made regarding the minimum requirements for characterizing the sheet, die, lubricant, and test conditions, and for reporting the results.

The serious deterioration in the international balance of payments of the U.S. can be reversed only by increasing the export of manufactured goods. Competition in the global market demands the lower-cost production of high-quality components for manufactured products. This, in turn, requires that product design be integrated with material development and process design, in an approach often described as simultaneous engineering. New technologies must be considered, often in competition with each other. These points are illustrated on the examples of microalloyed steel and austempered ductile iron, and some trends in the use of flat products, coatings, and composites are noted.