scholarly journals Experimental and modelling study of interaction between friction and galling under contact load change conditions

Friction ◽  
2021 ◽  
Author(s):  
Xiao Yang ◽  
Yiran Hu ◽  
Lemeng Zhang ◽  
Yang Zheng ◽  
Denis J. Politis ◽  
...  
Keyword(s):  
Dynamic Balance ◽  
Contact Load ◽  
Work Piece ◽  
Third Body ◽  
Material Transfer ◽  
Load Change ◽  
Pressure Dependency ◽  
Tool Surface ◽  
Pin On Disc ◽  
Dynamic Formation

AbstractThe galling process remains one of the least understood phenomena in metal forming. The transfer of material from a work-piece onto the tool surface can cause an evolutionary increase in friction coefficient (COF) and thus the use of a constant COF in finite element (FE) simulations leads to progressively inaccurate results. For an aluminium work-piece, material transfer, which has history and pressure dependency, is determined by a dynamic balance between the generation and ejection of wear particles acting as a ‘third body’ abrasive element at the contact interface. To address this dynamic interactive phenomenon, pin-on-disc tests between AA6082 and G3500 were performed under step load change conditions. The COF evolutions, morphologies of the transfer layer and its cross-section were studied. It has been found that contact load change will disequilibrate and rebuild the dynamic balance and high load will increase the generation and ejection rate of third body and vice versa. Moreover, based on the experimental results, an interactive model was developed and presented to simulate the dynamic formation process of the aluminium third body layer under load change conditions, enabling multi-cycle simulations to model the galling distribution and friction variation.

Influence of Tool and Workpiece Properties on the Wear of the Counterparts in Contact Sliding

2021 ◽  
pp. 1-24
Author(s):  
Wei Li ◽  
Liangchi Zhang ◽  
Chuhan Wu ◽  
Zhenxiang Cui ◽  
Chao Niu
Keyword(s):  
Friction Coefficient ◽  
Deep Drawing ◽  
Material Removal ◽  
Surface Hardness ◽  
Material Transfer ◽  
Workpiece Material ◽  
Treatment Processes ◽  
Coated Tool ◽  
Load Cells ◽  
Tool Surface

Abstract In a deep drawing process, the contact sliding between the surfaces of a metal sheet and a die/mould under high contact stresses brings about wear of both the counterpart surfaces. This paper aims to investigate the influence of tool and workpiece properties on the wear behaviours subjected to cylinder-on-flat sliding conditions. The effects of different tool materials (Cr12MoV, SKD11 and DC53), radii, surface hardness and surface treatment processes including thermal diffusion (TD) coating, nitriding coating and vacuum heat treatment (VHT) were investigated. Two types of workpieces with high tensile strength (DP980 and QP980) were also applied in the tests. The friction coefficient, surface morphology and material removal were analysed with the aid of load cells installed and microscopy measurements. It was found that the DC53 tool experiences the smallest tool wear and material transfer. The least material transfer is attributed to its low adhesion to workpiece material, which also results in more wear debris and higher friction coefficient. The TD coated tool surface can further improve the wear resistance and bring about the lowest friction coefficient. The debris density associated with the TD coating is also the smallest. These findings provide a useful guideline for the design and optimisation of moulds/dies for the deep drawing processes of sheet metals.

Mechanisms of the copper third body as an interfacial media on copper matrix friction materials with different compositions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiangyu Du ◽  
Junying Yang ◽  
Fei Gao ◽  
Xiaoming Han ◽  
Linlin Su
Keyword(s):  
Copper Powder ◽  
Copper Matrix ◽  
Third Body ◽  
Friction Materials ◽  
Content Type ◽  
The Third ◽  
Pin On Disc ◽  
Copper Component ◽  
New Perspective ◽  
Pure Cu

Purpose This paper aims to reveal the effects of the copper third body on different copper matrix friction materials with a novel experimental way called “exogenous powder.” Design/methodology/approach An accurate adding device of exogenous copper powder was designed to control the flow rate. The tribological properties with and without exogenous copper powder were investigated by a pin-on-disc tribometer during dry sliding. Findings Experimental results indicate that the Cu addition tends to increase the friction coefficient. For pure Cu material, the exogenous copper third body exhibits poor fluidity on the friction surface, causing serious adhesive wear on the friction interface. For the Cu 90% + 10% Gr material, the plasticity of exogenous copper powder may intensify the deformation of the third body of the surface, presenting layered accumulation distribution. For the pure Cu and Cu 95% + 5% SiO2 material, the Cu addition makes the composition and density of the third body uneven in the direction of depth. Originality/value The role of the copper component on different materials is revealed from a new perspective, and the relationship between the third body structure and the friction properties is explored.

A comprehensive microscopic study of third body formation at the interface between a brake pad and brake disc during the final stage of a pin-on-disc test

Wear ◽  
2009 ◽  
Vol 267 (5-8) ◽  
pp. 781-788 ◽  
Author(s):  
W. Österle ◽  
I. Dörfel ◽  
C. Prietzel ◽  
H. Rooch ◽  
A.-L. Cristol-Bulthé ◽  
...  
Keyword(s):  
Microscopic Study ◽  
Final Stage ◽  
Brake Disc ◽  
Brake Pad ◽  
Third Body ◽  
Body Formation ◽  
Pin On Disc

Friction and Wear Behavior of Boronized Chromium for Biological Applications

2005 ◽  
Author(s):  
R. Ribeiro ◽  
S. Ingole ◽  
O. Juan ◽  
H. Liang ◽  
M. Usta ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Surface Characterization ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Work Piece ◽  
X Ray Diffraction ◽  
Friction And Wear Behavior ◽  
Pin On Disc ◽  
Dry Conditions ◽  
Wear Mode

Enhanced corrosion and wear resistance are crucially important to prolong the service life of biomaterials. Boronizing has been reported to enhance the wear resistance of pure chromium. In this research, we investigate friction and wear behavior of boronized chromium. Pin-on-disc tribometer was used to conduct the wear and friction tests. Experiments were conducted in dry conditions as well as in simulated body fluid (SBF). Fundamental aspects of wear mode and lubrication behavior were studied using surface characterization techniques such as TEM, and X-ray diffraction. Results showed evidence of tribo-chemical interactions between SBF and work piece materials.

Dry Sliding Of Polygrained Quasicrystalline And Crystalline Al-Cu-Fe Alloys

1998 ◽  
Vol 553 ◽  
Author(s):  
D. J. Sordelet ◽  
J. S. Kim ◽  
M. F. Besser
Keyword(s):  
Friction And Wear ◽  
Sliding Friction ◽  
Wear Behavior ◽  
Dry Sliding ◽  
Material Transfer ◽  
Fracture Characteristics ◽  
Contact Loads ◽  
Pin On Disc ◽  
Fe Alloys ◽  
Transfer Mechanisms

AbstractDry sliding friction and wear experiments were performed with pin-on-disc techniques using WC and brass pins in contact with quasicrystalline (Al65Cu23Fe12) and crystalline (Al50Cu35Fe15and Al70Cu20Fe10) discs, which were prepared by powder metallurgy routes. The contact loads (1, 5 and 10 N) used in this study produced similar coefficients of friction 0.3-0.4 for the Al65Cu23Fe12and Al50Cu35Fe15phases. These values are higher than previously reported for quasicrystalline and related crystalline phases. Possible reasons for these differences are presented. The contrasting wear behavior between different pins and discs is discussed in terms of contact area, oxidation, material transfer mechanisms and fracture characteristics.

Tribological Performances of Two White Lubricants in Hot Steel Forging

2012 ◽  
Vol 504-506 ◽  
pp. 561-566 ◽  
Author(s):  
André Dubois ◽  
Mirentxu Dubar ◽  
Laurent Dubar ◽  
Brahim Tlili
Keyword(s):  
Contact Pressure ◽  
Hot Forging ◽  
Solid Particles ◽  
Organic Salt ◽  
Work Piece ◽  
Chemical Compositions ◽  
Sliding Velocity ◽  
Tool Surface ◽  
Sliding Test ◽  
Direct Results

The tasks of a lubricant used in the hot forging of steel is to reduce friction, cool down tool surfaces, and limit tool surfaces pollution by wear debris and oxides scales transferred from work piece surfaces. The most widely used lubricants in hot forging are dispersions of graphite particles in water or in oil. The graphite is involved to reduce friction. The liquid is used, first, to carry the graphite solid particles to the tool surfaces and, second, to reduce tool surface temperature. But graphite and vapours resulting from the lubricant deposition on hot surfaces lead to dirty workspaces. Some new lubricants are then developed in order to reduce friction in a cleaner way. When they are graphite free, those new lubricants are called “white lubricants”. The aim of the present work is to test two different white lubricants. The first one is a mineral salt; the second one is an organic salt. Lubricant performances are classified using the Warm and Hot Upsetting Sliding Test (WHUST). This friction bench simulates tests with contact pressure, sliding velocity, contactor and specimen temperatures similar to industrial ones. Before performing friction tests, work piece are heated up to 1200°C, contactors are heated up to 200°C, and lubricants are sprayed on contactor surfaces. Then the contactor slides against the specimen with a constant penetration, leaving a residual deformed track on its surface. Direct WHUST results are tangential and normal loads measured on contactor, surface roughness and chemical compositions on specimen and contactor surfaces. “Wear markers” are derived from those direct results, and provide useful information on the ability of the tested lubricants to reduce friction and protect tool surfaces. In the present study, tests are performed with different sliding speed and different contact pressure. The two white lubricants are compared to a generic graphite in water dispersion. Results show the tested white lubricants lead to coefficient of friction in the same range of the graphite lubricant one, but white lubricants lose their ability to reduce friction as soon as the sliding lengths becomes greater to 10 mm, where graphite lubricants can undergo sliding length greater than 30 mm.

Analysis of Material Transfer From a Soft Workpiece to a Hard Tool: Part I—Lump Growth Model

2000 ◽  
Vol 123 (3) ◽  
pp. 469-473 ◽  
Author(s):  
M. B. de Rooij ◽  
D. J. Schipper
Keyword(s):  
Shear Strength ◽  
Growth Model ◽  
Surface Hardness ◽  
Growth Behavior ◽  
Height Distribution ◽  
Material Transfer ◽  
Lower Shear ◽  
Tool Surface ◽  
The Individual ◽  
Transfer Mechanisms

An important mechanism reducing the lifetime of the deepdrawing tools is material transfer from the workpiece to the tool, resulting in the buildup of lumps on the tool surface. In this study, a lump growth model, based on transfer mechanisms observed in experiments, is developed. The development of the summit height distribution of the tool surface is calculated from the growth behavior of the individual lumps. Important parameters influencing material transfer are determined from the calculated summit height distributions. It follows that lump growth can be decreased and, under certain conditions prevented, by a higher (surface) hardness of the workpiece, a lower roughness of the tool surface, a lower nominal contact pressure, and a lower shear strength of the interface. These results are in general agreement with results obtained from experiments. Experimental results are presented in an accompanying paper (de Rooij and Schipper, 2000).

scholarly journals Phytoliths can cause tooth wear

2020 ◽  
Vol 17 (172) ◽  
pp. 20200613
Author(s):  
Fernando Rodriguez-Rojas ◽  
Oscar Borrero-Lopez ◽  
Paul J. Constantino ◽  
Amanda G. Henry ◽  
Brian R. Lawn
Keyword(s):  
Sliding Wear ◽  
Animal Species ◽  
Artificial Saliva ◽  
Wear Test ◽  
Tooth Wear ◽  
Wear Testing ◽  
Third Body ◽  
Pin On Disc ◽  
Molar Teeth ◽  
Wear Tests

Comparative laboratory sliding wear tests on extracted human molar teeth in artificial saliva with third-body particulates demonstrate that phytoliths can be as effective as silica grit in the abrasion of enamel. A pin-on-disc wear testing configuration is employed, with an extracted molar cusp as a pin on a hard disc antagonist, under loading conditions representative of normal chewing forces. Concentrations and sizes of phytoliths in the wear test media match those of silica particles. Cusp geometries and ensuing abrasion volumes are measured by digital profilometry. The wear data are considered in relation to a debate by evolutionary biologists concerning the relative capacities of intrinsic mineral bodies within plant tissue and exogenous grit in the atmosphere to act as agents of tooth wear in various animal species.

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