scholarly journals The Influence of Tool Texture on Friction and Lubrication in Strip Reduction Testing

2016 ◽  
Author(s):  
Mohd Hafis Sulaiman ◽  
Peter Christiansen ◽  
Niels Bay
Keyword(s):  
Metal Forming ◽  
Surface Texturing ◽  
Workpiece Material ◽  
Pocket Depth ◽  
Workpiece Surface ◽  
Drawing Speed ◽  
Lubrication Performance ◽  
Tool Surface ◽  
Lubricant Viscosity ◽  
Table Mountains

While texturing of workpiece surfaces to promote lubrication in metal forming has been applied for several decades tool surface texturing is rather new. In the present paper tool texturing is studied as a method to prevent galling. Adopting a strip reduction test longitudinal pocket geometries oriented perpendicular to the sliding direction, with shallow pocket depth, small pocket angle to the workpiece surface and varying distance between pockets are investigated. The experiments reveal that the distance between pockets should be larger than the pocket width thereby creating a topography similar to flat table mountains to avoid mechanical interlocking in the valleys; otherwise an increase in drawing load and pick-up on the tools is observed. The textured tool surface lowers friction and improves lubrication performance provided that the distance between pockets is 2-4 times larger than the pocket width. Larger drawing speed facilitates escape of the entrapped lubricant in the pockets. Testing with low to medium viscosity oils leads to a low sheet roughness on the plateaus but also local workpiece material pick-up on the tool plateaus. Large lubricant viscosity results in higher sheet plateau roughness but also prevents pick-up and galling.

Tool Surface Topographies for Controlling Friction and Wear in Metal-Forming Processes

1998 ◽  
Vol 120 (3) ◽  
pp. 517-527 ◽  
Author(s):  
Simon Sheu ◽  
Louis G. Hector ◽  
Owen Richmond
Keyword(s):  
Surface Topography ◽  
Metal Forming ◽  
Friction And Wear ◽  
Workpiece Surface ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Single Scale ◽  
Surface Topographies ◽  
Tool Surface ◽  
Scale Surface

A conceptual framework is introduced for the design of tool surface topographies in bulk metal forming processes. The objective of the design is to control friction to desired levels while minimizing wear of the workpiece and tool surfaces and adhesive metal transfer between the workpiece and tool. Central to the design framework are the tool/workpiece interface properties of lubricant retention and interface permeability. Lubricant retention refers to the capacity of an interface to retain lubricant rather than freely channel it to the exterior of the tool/workpiece conjunction. Permeability refers to the capacity to distribute lubricant to all areas within the conjunction. These properties lead to the concept of two-scale surface topography consisting of a fine scale background of interconnected channels on which is superimposed an array of coarser-scale cavities. Control of friction and wear is achieved by designing the tool surface topographies at these two scales to address the unique tribological conditions of specific bulk metal forming processes. The coarser scale is designed to ensure adequate supply of lubricant within the conjunction. The finer scale is designed to ensure adequate delivery of lubricant to all parts of the conjunction where nascent workpiece surface is being formed. The design concepts are illustrated with results from laboratory experiments using the rolling process as an example, and comparing the performance of various roll surface topographies under similar processing conditions. A two-scale surface topography consisting of hemispherical cavities distributed across a background surface of finer scale, interconnected channels was shown to reduce friction compared to a single-scale ground finish, but not as much as a single-scale coarse topography consisting of densely-packed cavities produced by an electrical discharge treatment. On the other hand, the smoother cross-sections of the cavities, especially when elongated in the direction of greatest relative motion, produced significantly less wear than either of the single-scale tool surface treatments. It is concluded that two-scale engineering of tool surface topographies based upon the concepts of lubricant retention and interface permeability can provide a broad basis for achieving desired levels of interface friction while minimizing workpiece surface wear and adhesive material transfer in many metal-forming processes.

Investigation of the Suitability of Surface Treatments for Dry Cold Extrusion by Process-Oriented Tribological Testing

2015 ◽  
Vol 651-653 ◽  
pp. 473-479 ◽  
Author(s):  
Marco Teller ◽  
Markus Bambach ◽  
Gerhard Hirt ◽  
Ingo Ross ◽  
André Temmler ◽  
...  
Keyword(s):  
Metal Forming ◽  
Adhesive Wear ◽  
Pure Aluminum ◽  
Surface Treatments ◽  
Cold Extrusion ◽  
Workpiece Material ◽  
Initial Yield Stress ◽  
First Results ◽  
Tailored Surfaces ◽  
Steel Aisi

In cold extrusion of aluminum alloys adhesive wear can be prevented by an excessive lubrication of the process. While this causes additional process steps also environmental risks have to be addressed. Hence, dry metal forming, i.e. avoiding lubrication by means of coatings and topography modifications is highly desirable. In this paper first results concerning the behavior of tailored surfaces under dry metal forming conditions for pure aluminum are presented. Different surface treatments (laser polishing and Mo2BC coating) of the tool steel AISI H11 are tested in a compression-torsion-tribometer under conditions adapted from cold extrusion. Normal stresses six times higher than the initial yield stress of the tested workpiece material pure aluminum (AA1050-O) are applied. Furthermore, a strategy for the characterization of aluminum adhesions to the tool is introduced. The influences of different topographies and the presence of a coating on the loss of material due to adhesive wear are investigated.

A Markovian Finishing Process

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
M. A. S. Mohamed
Keyword(s):  
Triangular Form ◽  
Workpiece Surface ◽  
Finishing Process ◽  
Tool Surface ◽  
Markov Matrix ◽  
Abrasive Surface ◽  
Matrix Mapping ◽  
Abrasive Tools ◽  
Finishing Processes ◽  
Abrasive Paper

Addressed is the mechanism of finishing processes for a workpiece surface using hard abrasive tools such as grinding, abrasive paper, and filing. The mechanism is intended to monitor the gradual changes of the workpiece surface state roughness as the tool is applied for several strokes. Based on a number of common features, the present study simulates each rubbing stroke as a Markov process, and each set of several strokes as a Markov chain. In the simulating model, the discrete probabilistic properties of a specific tool abrasive surface can be expressed in terms of a corresponding Markov matrix operator. Thus, the tool action after one rubbing stroke is obtained via a matrix mapping from a given state roughness to a subsequent state roughness of the workpiece surface. Although the suggested model is capable to handle a comprehensive finishing mechanism, the study focuses on the simple case of zero feeding using a hard abrasive tool, in which the Markov matrix shrinks to a special triangular form. Main findings show that major aspects of the tool surface are transferred to the stepwise roughness state of the workpiece immediately after the first stroke. In addition, regardless of the initial roughness state of the workpiece surface, whether with flat or randomly distributed heights, the ultimate state roughness is unique and definitely features the theoretical case of a plain flat surface. However, this theoretical case is infeasible since it can only be reached after infinite number of strokes.

scholarly journals Tool surface with a supporting plateau of hard particles for deep drawing of high alloy steel

2018 ◽  
Vol 190 ◽  
pp. 14006 ◽  
Author(s):  
Hannes Freiße ◽  
Thomas Seefeld
Keyword(s):  
Sheet Metal Forming ◽  
Deep Drawing ◽  
Metal Forming ◽  
Adhesive Wear ◽  
High Alloy ◽  
High Alloy Steel ◽  
Hard Particles ◽  
Aluminium Bronze ◽  
Tool Surface ◽  
Alloy Steels

Sheet metal forming normally requires the application of lubricants to protect the tool and the sheet against wear. The parts must be cleaned to remove the lubricants before joining and coating. This process step wastes energy and water resources. In the case of non-lubricated sheet metal forming, cleaning processes would not be necessary anymore and the process chain could be optimized regarding ecological and economical aspects. However, forming without lubrication leads to an intensive contact between the tool and the sheet. Thus, higher wear occurs and process reliability cannot be ensured for industrial mass production. High alloy steels are applied for mass-market products e.g. for appliances. Because of the higher strength, strain hardening and galling effects the austenitic steels are comparatively difficult to form. For dry metal forming of high alloy steels new tool concept must be developed to withstand the higher loads. In this work, a laser generated tool surface with a supporting plateau of hard particles (metal matrix composite (MMC-surface)) is presented. Spherical fused tungsten carbides were injected into the surface by laser melt injection. The metallic matrix of the composite was rejected by applying laser ablation. In consequence, the hard particles stood out of the matrix and were in direct contact with the sheet material. The surface of hard particles had a high hardness about 3000 HV and less metallic character. Cold working steel and aluminium bronze were tested as reference tool materials. Dry and lubricated forming experiments were carried out by strip drawing with bending and deep drawing of cups. Dry deep drawing of cups was not possible by using cold work tool steel. This can be traced back to the occurrence of wrinkles and cup base fracture at the same time. Applying aluminium bronze as tool material for dry metal forming resulted in high adhesive wear. Within this work the feasibility of dry metal forming of high alloy steel could be demonstrated by applying the MMC-surface whereby adhesive wear could be reduced.

Influence of micro-grooves on the lubrication performance of a misaligned bearing

2019 ◽  
Vol 234 (6) ◽  
pp. 887-899
Author(s):  
Yanxiang Han ◽  
Yonghong Fu
Keyword(s):  
Angular Position ◽  
Surface Texturing ◽  
Mass Conservation ◽  
Groove Depth ◽  
Film Rupture ◽  
Practical Applications ◽  
Numerical Predictions ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Manufacturing Tolerances

Surface texturing for improving the lubrication performance of journal bearings has been widely investigated in the last two decades. In practical applications, the misalignment of a journal bearing occurs due to the asymmetric bearing load, elastic deflection, manufacturing tolerances, and installation errors. However, there has been little discussion on the influence of grooves on the lubrication performance of misaligned bearings. In the present work, numerical predictions of lubrication performances are presented to test the influence of the grooves. Based on the JFO boundary condition, a mass conservation algorithm is implemented to automatically determine the position of oil film rupture and reformation. The load-carrying capacity, friction force, friction coefficient, and bearing moment are computed numerically. The influence of angular position of the groove is first conducted in a misaligned bearing. Subsequently, the groove depth and width are investigated with different values of [Formula: see text] and [Formula: see text] ratios, respectively.

Investigation into LST and its Novel Application in Mould

2007 ◽  
Vol 24-25 ◽  
pp. 189-194
Author(s):  
Yun Wang ◽  
Z.Y. Xu ◽  
Y.H. Fu ◽  
Lan Cai
Keyword(s):  
Laser Beam ◽  
Material Removal ◽  
Surface Engineering ◽  
Surface Texturing ◽  
Industrial Applications ◽  
Laser Surface Texturing ◽  
Intense Laser ◽  
Full Potential ◽  
Workpiece Surface ◽  
Factors Affecting

Laser surface texturing (LST) technology that is firstly used in rollers, is a specialized surface engineering process capable of enhancing the surface material properties, wear resistance, fretting fatigue life and reducing friction. This practical technology of the LST process is based on a pulsating laser beam that, by material ablation, generates the optimum topographical surface. In order to exploit the full potential of the process, a great amount of research has explored from the material removal mechanics to the development of the LST process. This paper reports on the LST research involving the LST technology surveying process optimization, LST equipment and its industrial applications. The paper also highlights the forming theory describing the skin-pass process of transferring the textured roller’s surface structure onto the steel sheet, and the laser-matter interaction that occurs when and intense laser beam is tightly focused in the workpiece surface. It presents the influence of various factors affecting the textured workpiece performance together with the investigations into tribology of textured components. The paper also discusses these developments and some fundamental on future LST research.

Control of the material flow in sheet-bulk metal forming using modifications of the tool surface

2018 ◽  
Vol 12 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Maria Löffler ◽  
R. Schulte ◽  
D. Freiburg ◽  
D. Biermann ◽  
D. Stangier ◽  
...  
Keyword(s):  
Metal Forming ◽  
Material Flow ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Tool Surface

Description of the contact between a deterministic anisotropic tool surface and a workpiece subjected to plastic deformation

1998 ◽  
Vol 212 (5) ◽  
pp. 403-409 ◽  
Author(s):  
M-I Rotarescu
Keyword(s):  
Metal Forming ◽  
Inverse Method ◽  
Sliding Friction ◽  
Critical Issue ◽  
The Finite Element Method ◽  
Contact State ◽  
Tool Surface ◽  
Grooved Surface ◽  
Workpiece Interaction ◽  
Upsetting Test

The finite element method offers an opportunity to obtain important information by simulating metal-forming processes. The description of the tool—workpiece interaction still remains a critical issue. The aim of this paper is to describe the contact between a deterministic anisotropic tool surface (grooved) and a workpiece. This is done by means of an existing contact processor and a friction law that has been conceived to describe sliding friction. This compromise solution of describing a contact state near to sticking by means of a law created for sliding friction is investigated. The results obtained using a macrogeometric model of the grooved surface are compared to those achieved by an idealized smooth surface and different friction coefficients. Next, an anisotropic model is introduced and calibrated using the inverse method based on the ring upsetting test for a hot-worked steel.

Strengthening Mechanisms of 1H18N9T Austenitic Steel Buildups Created with Cold Forming Processes

2007 ◽  
Vol 23 ◽  
pp. 165-168 ◽  
Author(s):  
W. Presz ◽  
M. Kaczorowski
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Metal Forming ◽  
Surface Damage ◽  
Strengthening Mechanism ◽  
Additional Mechanism ◽  
Cold Forming ◽  
Pressure Surface ◽  
Tool Surface

In metal forming processes in the tool-workpiece contact area occur high pressure, surface expansion and elevated temperature. It makes ideal circumstances for braking of the lubricant film that causes a direct contact between metallic surfaces. Such a contact usually leads to buildups creation on the tool surface. These phenomena mainly result product surface damage. Damages can also refer to tool surface since the hardness of buildups can be comparable with the tool hardness. The cause of this investigation was finding the answer of the question what was the reason of extreme hardness of buildups created during bulk metal forming processes of 1H18N9T austenitic stainless steel. The studies were conducted using transmission electron microscopy (TEM). On the basis of analysis structural and electron diffraction pattern it was suggested that simultaneously to very well known strengthening mechanism like grain refinement, the additional mechanism can not be excluded. Based mostly on the electron diffraction pattern (appearance of forbidden reflexes for FCC) it is suggested that this additional mechanism could be the marthensitic transformation caused by very high plastic deformation.

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