Influence of Hammer-Peened Surface Textures on Friction Behavior

Steitz, Manuel; Stein, Peter; Groche, Peter

doi:10.1007/s11249-015-0502-9

Cited by 19 publications

(12 citation statements)

References 16 publications

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“…The lower friction coefficients of coatings at the smaller spray angles is believed to result from better water lubrication condition with moderately 13 higher coating porosity of well-dispersed micro-pores. The improvement in tribological behavior with reduced friction coefficient with higher porosity is analogous to the observed lubricant pocket effect of intentionally patterned surfaces with small dimples under [34,35].…”

Section: Wear Performance Of Hvof Wc-ni Coatings At Off-angle Sprayingmentioning

confidence: 53%

Water-lubricated tribological behavior of WC-Ni coatings deposited by off-angle HVOF spraying

Zhu

Meng

et al. 2017

Surface and Coatings Technology

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The off-angle thermally sprayed coatings generally present noticeable degradation in coating feature and characteristic, such as density, microhardness and/or toughness. A critical spray angle was previously suggested for different thermal spray techniques, e.g.HVOF of 45°, wire arc spraying of 60°, plasma spraying of 50° or 45°, primarily based on degree of the degradation benchmarked on that of normal angle. In this study, the feasibility of off-angle HVOF spraying of WC-Ni coatings is clarified directly by wear performance under water lubrication, since reported wear test results seem to be controversial. It is found that, the coating porosity is almost tripled with an upper limit within 3% as reducing the spray angle from 90° to 30°, while the maximum variation in the WC phase retention is about 13.6%, and about 11.7% in both microhardness and elastic modulus, and about 26.4% in indentation fracture toughness, respectively. As compared to a reported dry abrasive wear test showing that specific wear rate of HVOF WC-Co coatings at a spray angle of 30° was nearly doubled to that of 90° within 10 -4 -10 -5 mm 3 /Nm, our water-lubricated wear test shows a comparably low specific wear rate below 10 -7 mm 3 /Nm with about 30% maximum variation for WC-10Ni coatings off-angle sprayed with respect to that of normal spray angle. A notable reduction in friction coefficient is confirmed for off-angle sprayed coatings at 30° and 45°. The improved tribological behavior is mainly attributed to the higher porosity with well-dispersed micro-pores facilitating a better water lubrication, as well as the mostly retained mechanical properties of off-angle coatings due to controlled porosity in a certain range. The off-angle sprayed WC-Ni coatings down to the spray angle of 30° are applicable in tribological applications due to improved fluid lubricating characteristic.

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Section: Wear Performance Of Hvof Wc-ni Coatings At Off-angle Sprayingmentioning

confidence: 53%

Water-lubricated tribological behavior of WC-Ni coatings deposited by off-angle HVOF spraying

Zhu

Meng

et al. 2017

Surface and Coatings Technology

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“…In dry forming, surfaces with lower roughness show a reduced risk to galling [18]. For a tribological system with lubricant, on the contrary, application of lubricant pockets on the tools made by machine hammer peening is found to be favorable and the positive influence of such lubricant pockets on the friction and wear behavior has been proven [19]. However, the life span of tools with rough surfaces has not been researched adequately in sheet metal forming.…”

Section: Influence Factors Of Wear In Sheet Metal Formingmentioning

confidence: 99%

Influence of Tool Finishing on the Wear Development in Strip Drawing Tests with High Strength Steels

Groche

2020

Tribology Online

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With the increasing usage of high-strength steel, tool wear becomes a major challenge in sheet metal forming. As tribological properties are in consequence of the system characteristics, wear prediction is extremely difficult. The wear resistance characteristic curve is introduced in a former publication of the authors to predict wear in sheet metal forming. With the help of this curve, the evaluation of the tool life spans in strip drawing tests under different contact pressures is possible. However, other influencing factors on tool wear should also be taken into account. In this paper, two types of tools made from cold working steel and cast iron are used to investigate the influence of the tool characteristics hardness and surface roughness on the wear behavior and the life span in strip drawing tests with high strength steels. Moreover, the dominating wear mechanisms with respect to different tool properties are also discussed. As a consequence, the wear resistance characteristic curves are derived and new values to characterize the wear resistance in terms of hardness and surface roughness are presented. With the results, more knowledge about the influencing factors on wear is given and the life spans of different tribological systems can be quantitatively predicted. Finally, the wear behavior of the tools after rework is also discussed.

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“…for deep drawing of sheet metal parts in the automotive industry or household appliances, the authors focused on the investigation into the MHP influences on tribology characteristics in lubricated sliding contacts like deep drawing. Using adapted MHP parameters, deterministic structures could be applied, which have advantageous tribological properties regarding friction [13].…”

Section: Initial Situationmentioning

confidence: 99%

Analysis of the Velocity Distribution of an Elliptic Surface Structure Manufactured by Machine Hammer Peening

et al. 2015

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Machine hammer peening (MHP) is an incremental forming process for surface structuring of technical workpieces or tools. Currently, MHP strongly attracts the attention of automotive and toolmaking industry. Recently performed research showed improved tribological characteristics in lubricated deep drawing in terms of a reduced friction coefficient due to a lubricant pocket effect and a reduced contact area. In order to design the MHP process to obtain an optimized load capacity of the fluid film, the velocity distribution has to be analyzed. Thus, an analytic approach for solving the Reynolds equation as a valid simplification of the Navier-Stokes equations for an elliptic geometry of a MHP structure is proposed in this work. The research assumes stationary hydrodynamic lubrication and is restricted to the longitudinal properties. Thereby, the influence of the structure geometry, the fluid film thickness, the sliding velocity and the dynamic viscosity on the fluid velocity distribution is researched by means of an analytic solution of the Reynolds equation. The derived formula is applied to contribute to the understanding in lubricated deep drawing with MHP structures, but is also transferable on further sliding contacts, e.g. bearing lubrication.

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Influence of Hammer-Peened Surface Textures on Friction Behavior

Cited by 19 publications

References 16 publications

Water-lubricated tribological behavior of WC-Ni coatings deposited by off-angle HVOF spraying

Water-lubricated tribological behavior of WC-Ni coatings deposited by off-angle HVOF spraying

Influence of Tool Finishing on the Wear Development in Strip Drawing Tests with High Strength Steels

Analysis of the Velocity Distribution of an Elliptic Surface Structure Manufactured by Machine Hammer Peening

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