Effect of triangular oil pockets on friction reduction

Author(s):  
Slawomir Wos ◽  
Waldemar Koszela ◽  
Andrzej Dzierwa ◽  
Pawel Pawlus

The effect of the apex angle of triangular oil pockets created on a disc surface on friction was studied. Experiments were carried out using an Optimol SRV5 tribotester equipped with a pin-on-disc module under unidirectional lubricated sliding. Both the sample and counter sample was made of steel of 45 Hardness Rockwell C (HRC) hardness. Only 1 ml of oil was put to the inlet side of the contact area at the beginning of each test. All textured surfaces had the same pit-area ratio and an average depth of dimples. Oil pockets were positioned in the spiral array. It was found that the effect of the apex angle of triangular dimples on friction reduction was important. When the normal load was lower, the smallest coefficient of friction was achieved for the sliding pair with a disc apex angle of 60°. Under a larger normal load, a higher apex angle corresponded to a higher coefficient of friction.

2015 ◽  
Vol 67 (4) ◽  
pp. 328-335 ◽  
Author(s):  
Avinash A. Thakre ◽  
Animesh Thakur

Purpose – The purpose of this paper is to include investigation on extreme pressure lubrication behaviour of Al2O3 nanoparticles suspended in SAE20W40 lubricating oil. Effects of nanoparticles size (40-80 nm) and its concentration (0-1 per cent) on the coefficient of friction is studied using pin-on-disc tribotester. Design/methodology/approach – Taguchi technique is used to optimize the process parameters for lower coefficient of friction. L18 orthogonal array involving six levels for one factor and three levels for remaining three factors is selected for the experimentation. The parameters selected for the study are sliding speed, normal load, nanoparticles size and its concentration in base oil. Findings – It has been found that the presence of nanoparticles in proper concentration shows excellent tribological improvement in frictional characteristics compared to the base oil. The optimal combination of the parameters for minimum coefficient of friction is found to be 0.8 per cent concentration of 60 nm sized Al2O3 nanoparticles, 1,200 rpm sliding speed and 160 N of normal load. The mechanism of friction reduction in presence of nanoparticles is investigated using scanning electron microscopy. Originality/value – This is the original work.


Tribologia ◽  
2017 ◽  
pp. 97-105 ◽  
Author(s):  
Sławomir WOŚ ◽  
Waldemar KOSZELA ◽  
Paweł PAWLUS

Experiments were carried out using pin-on-disc tester in conformal lubricated contact conditions for different normal loads. Surface texturing was done using abrasive jet machining with the application of laser cut mask. In order to eliminate the effect of different input variables in all the experiments, pit-area ratio and sizes of oil pockets were very similar. Five types of oil pocket arrays were tested: radial, concentric, spiral, of a square arrangement, and of a random arrangement for 5% and 17% of pit-area ratio. Different dimple diameters caused various oil pocket densities. The experiments were also made for untextured polished discs. During tests, the friction force was monitored as a function of time. Before and after tests, disc surface topography was measured using a white light interferometer Talysurf CCI Lite. The beneficial effect of surface texturing was obtained for spiral arrays of dimples on disc surface. The presence of a radial array of oil pockets resulted in the worst tribological properties of tribological assemblies containing textured discs.


Author(s):  
H.-S. Zhang ◽  
K. Komvopoulos

Silicon wafers were exposed to an oblique Ar+ ion beam to create arrays of surface ripples. Atomic force microscope (AFM) imaging revealed that the rippled (textured) surfaces exhibited highly anisotropic morphologies. Nanoscale friction experiments performed with different diamond tips illustrated a dependence of the coefficient of friction on tip radius, normal load, and sliding direction. Changes in the coefficient of friction are interpreted in terms of the applied normal load and varying contributions of the adhesion friction mechanism.


Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4886
Author(s):  
Agnieszka Lenart ◽  
Pawel Pawlus ◽  
Andrzej Dzierwa ◽  
Slawomir Wos ◽  
Rafal Reizer

Experiments were conducted using an Optimol SRV5 tester in lubricated friction conditions. Steel balls from 100Cr6 material of 60 HRC hardness were placed in contact with 42CrMo4 steel discs of 47 HRC hardness and diversified surface textures. Tests were carried out at a 25–40% relative humidity. The ball diameter was 10 mm, the amplitude of oscillations was set to 0.1 mm, and the frequency was set to 80 Hz. Tests were performed at smaller (45 N) and higher (100 N) normal loads and at smaller (30 °C) and higher (90 °C) temperatures. During each test, the normal load and temperature were kept constant. We found that the disc surface texture had significant effects on the friction and wear under lubricated conditions. When a lower normal load was applied, the coefficient of friction and wear volumes were smaller for bigger disc surface heights. However, for a larger normal load a higher roughness corresponded to a larger coefficient of friction.


Tribologia ◽  
2016 ◽  
Vol 267 (3) ◽  
pp. 195-204
Author(s):  
Sławomir WOŚ ◽  
Waldemar KOSZELA ◽  
Paweł PAWLUS

Various machining methods are currently used to obtain the best co-action of sliding surfaces. Application of two-process surfaces led to a decrease of frictional resistance. Textured surfaces after abrasive jest machining are practical examples of two-process topographies. The results of the application of textured discs with the same array of oil pockets of similar sizes, but with different roughness in areas free of dimples, are presented in this paper. It was determined that after this type of machining, the effect of the friction force decrease was caused by surface texturing.


Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 221 ◽  
Author(s):  
Slawomir Wos ◽  
Waldemar Koszela ◽  
Andrzej Dzierwa ◽  
Pawel Pawlus

Surface texturing is an option of surface engineering resulting in reduction of friction due to the creation of isolated dimples or grooves on sliding surfaces. The purpose of this work is to find the effect of the groove bottom profiles on the reduction of the friction force. Investigations were conducted using an Optimol SRV5 tribotester equipped with a pin-on-disc module. A disc made of 42CrMo4 steel, with a 100 mm diameter acted as a sample. A counter-sample was made of the same material, however, its diameter was 20 mm. The sliding conditions were selected to be similar to those of a sliding crankpin bearing pad operating in a high-performance internal combustion engine. Surface texturing was found to be beneficial for a reduction in the friction coefficient up to 55% in comparison to the untextured disc. Tribological performances of discs with spiral groove patterns were better than those with a radial layout. In most cases the convergent profile of the groove bottom was superior to the dam shape.


2013 ◽  
Vol 388 ◽  
pp. 63-67
Author(s):  
Samion Syahrullail ◽  
Muhammad Amirul Abdul Rahman

Palm fatty acid distillate (PFAD) has potential to be used as a lubricant. PFAD is a by-product from palm oil refinery, and it is classified as non-edible oil. However, vegetable oil has poor thermal performance and high oxidation rate. In this paper, the tribological performance of PFAD in different working temperature was investigated by using four-ball tribotester. Tests were conducted at temperatures 50oC, 75oC, 100oC and 125oC, under a normal load of 40 kg for one (1) hour. The rotational speed was set at 1200rpm. Similar tests were conducted using industrial hydraulic oil as a comparison lubricant. Analyses were focused on the coefficient of friction (CoF), wear scar diameter (WSD) and worn surface observation. Results show that coefficient of friction and wear were increased with the increment of temperature. However, palm fatty acid distillate show a better performance in term of friction reduction compared to industrial hydraulic oil.


Author(s):  
P Venkateswara Babu ◽  
Syed Ismail ◽  
B Satish Ben

Textured surfaces have been remarkable in improving the frictional performance of sliding contacts, particularly at instances such as boundary or mixed lubrication regimes. This article reports the results of an experimental and numerical study carried out by introducing surface textures in the form of protrusions to investigate its effects on friction performance under a mixed lubrication regime. The surface textures produced by the chemical etching process are tested on the pin on disc test rig by varying area density and height of the texture. In numerical simulation, the modified Reynolds equation (Patir–Cheng flow model) and asperity contact model (Greenwood–Tripp model) are solved for hydrodynamic and asperity pressures, respectively. The results indicate that the experimental measurements are qualitatively in good agreement with numerical predictions. Furthermore, the simulations are performed for different texture shapes by varying texture area density, height, and sliding velocity. The results depict that a maximum friction reduction of 87% with elliptical textures compared to the un-textured case.


2011 ◽  
Vol 110-116 ◽  
pp. 616-620 ◽  
Author(s):  
S. Ilaiyavel ◽  
A. Venkatesan ◽  
N. Nallusamy ◽  
T. Sornakumar

Manganese Phosphate is an Industrial coating used to reduce friction and improve lubrication in sliding components. In this study, the tribology behavior of uncoated, manganese phosphate coated, Manganese Phosphate with oil lubricant AISI D2 steels was investigated. The Surface morphology of manganese phosphate coatings was examined by scanning electron microscope (SEM) and Energy dispersive X-ray Spectroscopy (EDX) .The wear tests were performed in a pin on disk apparatus as per ASTM G-99 Standard. The wear resistance of the coated steel were evaluated through pin on disc test using a sliding velocity of 0.35 m/s under normal load of 5 to35 N and controlled condition of temperature and humidity. The Coefficient of friction and wear loss were evaluated. Based on the results of the wear test, the manganese phosphate with lubricant exhibited the lowest average coefficient of friction 0.13 and the lowest wear loss 0.4 mm3under 35 N load.


2014 ◽  
Vol 591 ◽  
pp. 81-84
Author(s):  
M. Pradeep ◽  
Packkirisamy Vignesh ◽  
M. Arun ◽  
M. Durairaj

Influence of surface roughness on coefficient of friction of Titanium coated R19 Steel is investigated in this paper using Pin on Disc Apparatus. Wear properties of R19 Steel are evaluated because it is widely used in making the rail wheel and rail roads over the years. Titanium coating of 100nm thickness was deposited on the R19 Steel by Electron Beam Gun Physical Vapor Deposition method. Wear and friction parameters were evaluated using Pin on Disc apparatus. The Surface morphology plays an important role in affecting the wear rate. Non-contact surface roughness tester was used to examine the surface texture and measure the surface roughness of the specimens. The test was carried out in a pin on disc apparatus for Normal Load of 15N, Sliding Velocity of 3m/s and Time 5 min. The texture and the roughness parameters of the surface affect the coefficient of friction. The experimental values of roughness parameters of uncoated and coated disc and its effect on coefficient of friction are compared and validated. Results show that the Coefficient of friction decreases with lower value of Ra. Lower values of frictional force and coefficient of friction results in lower wear rates.


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