Experimental study on the effect of different speeds applied with palm olein using pin-on-disk tester

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1 Applied Mechanics and Materials Vol. 315 (2013) pp Online available since 2013/Apr/10 at (2013) Trans Tech Publications, Switzerland doi: / Experimental study on the effect of different speeds applied with palm olein using pin-on-disk tester M.I.Izhan 1, a, J.Y.Wira 2,b, M.R.Abdul Kadir 3,c and S.Syahrullail 4,d 1 School of Graduates Studies, Universiti Teknologi Malaysia, UTM Skudai, Johor, Malaysia. 2 Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia Kuala Lumpur, Jalan Semarak, Kuala Lumpur, Malaysia. 3 Faculty of Biomedical Engineering & Health Science, Universiti Teknologi Malaysia, UTM Skudai, Johor, Malaysia. 4 Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, UTM Skudai, Johor, Malaysia. a m_izhan16@yahoo.com, b wira@ic.utm.my, c rafiq@biomedical.utm.my, d syahruls@fkm.utm.my Keywords: Palm oil, pin-on-disk tribotester, friction coefficient, wear Abstract. The wide use of conventional lubricants causes pollution to the environment and the rising awareness on green house effect has triggered the use of environmental friendly and biodegradable lubricants in the industries. Palm olein was selected to be a candidate due to its superior tribological properties and large production in country. In the research, the behavior of palm olein characteristic was investigated by using pin-on-disk experiment in which the pin was loaded against the rotating grooved disk. The experiments by sliding were performed via pin on disk tester using stainless steel as the material for both flat ended pin and grooved disk. The test were carried out by dropping 5 ml of palm olein as lubricant on the sliding surface at two different speeds which were 0.25 and 1 m/s. In this study, the wear rate of the pin and friction coefficient was investigated. The weight loss and surface roughness before and after experiment were analyzed. All the results obtained were compared to hydraulic oil and paraffinic mineral oil. From the analysis, friction coefficient acquired with lubrication of palm olein was the lowest for both conditions, while the wear rate obtained also showed a similar trend. The pin lubricated with palm show the lowest result of wear rate and weight loss. Introduction The main problems faced by the industrial field nowadays are the wear and friction compilation of the machine and engine. These problems are the significant material failure modes that could lead to other failures such as fatigues of machine components, thus delaying the productions. Energy conservation and technological civilization have become increasingly important. It is widely accepted that wear and friction primarily changes with load, speed [1], temperature [2], surface roughness [3,4], type of material or mating component and environmental factor. In order to reduce undesirable effects of wear and friction, the use of lubricant is an excellent alternative applied in engine and machines. Lubricant is a substance used to reduce friction and wear and provides smooth running and satisfactory life for machine elements. Besides that, lubricant can also be used to recede the heat by circulation and cooling thus increasing the reduction of wear and friction of mating components. In the lubricant selection or lubricant development, wear resistance, higher load capabilities and temperature stability are important parameters. Fossil fuel, especially petroleum is very essential energy sources on the earth. Conventional lubricants are petroleum based and are widely used in industries nowadays. However, recent decades show severe ecological pollution related to conventional lubricants. Nearly 12 million tons of lubricant wastes are disposed into the environment [5]. Conventional oil presents noticeable risk for the environment or for safety due to some degree of toxicity and generally high flammability. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, (ID: , Universiti Teknologi Malaysia, Johor Bahru, Malaysia-28/05/13,06:36:46)

2 Applied Mechanics and Materials Vol Due to the reason stated above, researchers are rapidly in effort to find a preeminent alternative lubricant to replace conventional lubricant. There has been a growing awareness for the utilization of vegetables oils and fats for machineries due to their technical, environmental and strategic advantages. The presence of vegetables oil as lubricants is attributed to the decrease of mineral oil application in industry. Vegetable oils, also known as environmentally friendly lubricants, were selected due to several advantages such as high biodegradability, low friction coefficient, nontoxicity, renewable resources, good low temperature properties and low cost [6]. Vegetable oils are not a new discovery and its advantages are already widely known even in Ancient Egypt, where they used vegetable oils in construction of monuments. To study wear of the materials, the process of wear in a controlled manner and studied the effect on different samples with the same test conditions by performing pin-on-disk test we conducted. The experiments were run for 1 hour at constant load 10 N and different speeds of 0.25 and 1.0 m/s. The results showed that RBD palm olein has better lubricating properties for the reduction of wear and friction. Experimental Procedure Apparatus. In the present investigation, pin on disk had been used to study both wear and coefficient of friction. The pin-on-disk test is commonly used as a comparative test in which controlled wear is performed on the samples to study. The volume lost allows the calculation of the wear rate of the material. A pin is clamped firmly against a rotating disk linked to a certain dead weight with a beam and two pulleys. Lubricating oil will be placed on the surface of grooved disk. In this experiment, a modified pin on disk was used. The lubricant was not pumped and let to flow through the disk. A 5 ml of the lubricant was dropped on the disk and to make sure the lubricant do not flow out while the disk rotated, the disk was designed to have a groove with 10 mm width and 5 mm depth. A linear voltage differential transformer (LVDT) sensor plays an important role to read wear rate. The grooved disk needed to be cleaned before the experiment by using acetone. The surface roughness was recorded according to the parameter set up by researcher. Fig. 1 shows the schematic sketch of the pin and grooved disk. Fig. 1 Schematic sketch of the pin and grooved disk. Materials and lubricants. Studies of wear and friction coefficient behavior were performed with a flat ended pin, made from stainless steel, was chosen for the experiment. Pin samples were prepared as 8 mm in diameter and 30 mm in length. The density of stainless steel is 7.48 g/cm 3. A stainless steel grooved disk had been selected as shown in Fig. 1. Upon the completion of each test, abrasive paper with the grain size of the abrasive material of 1000 micron was used to grind the surface so that the surface finished was between specifications. The surface roughness of the disk was measured using a surface roughness profiler which consisted of a stylus detector to determine the pattern of disk and pin surface. RBD palm olein, hydraulic oil and paraffinic mineral oil were used as lubricants with the same amount of oil which was 5 ml. Experimental procedure. Lubricated friction and sliding wear testings were carried out using a conventional pin on disk machine. A flat-on-flat surface as test arrangement was used for the present set of experiments. Both the surface of the pins and disk were made parallel to ensure their maximum contact. The principle of sliding required a cantilever loaded pin against horizontal rotating grooved disk in a lubricant oil bath. All the tests were carried out at room temperature, 24±

3 948 Mechanical & Manufacturing Engineering 2 C. In this experiment, the constant load and different sliding speeds were predicted to affect the friction and wear characteristics. Pin samples before and after each test and weight losses were recorded. During the wear and friction coefficient test, different speeds were applied which were 0.25 and 1 m/s respectively using three different types of lubricant. The surface finish of wear sample and grooved disk were measured before and after experiment. Results Effect of sliding speed on friction coefficient. To study the antifriction behavior of RBD palm olein, several experiments were implemented using different speeds which were 0.25 and 1.0 m/s at constant 10 N load. The duration of the experiment was 1 hour. All data related to frictional force were collected and were converted into friction coefficient (µ) using Eq. 1, where F is a frictional force and N is a normal load. F µ = (1) N The curves for both conditions are illustrated and exhibited in Fig. 2. At low speed of 0.25 m/s, the value shows that friction coefficient with lubrication of RBD palm olein was the lowest compared to paraffinic mineral oil and hydraulic oil. The friction coefficient increased sharply at the early time of running experiment, and became constant when they reached the steady state for all the test lubricants. The final state friction coefficient obtained for RBD palm olein was and paraffinic mineral oil was respectively, while the result for hydraulic oil was in this experiment. For high speed of 1.0 m/s, the lubricants approximately showed similar trend from the initial to completion of experiment, which the friction coefficient obtained was increasing as the increment of sliding time. The friction coefficient with lubrication of palm olein was the lowest compared with the other two lubricants. The steady state friction coefficient obtained for RBD palm olein was and paraffinic mineral oil was respectively, while the result for hydraulic oil was in this experiment. From the analysis, the friction coefficient decreases as the sliding increases for RBD palm olein and hydraulic oil. The friction coefficient with lubrication of paraffinic mineral oil increased as the sliding speed increased. Friction coefficient PO HO PMO Lubricant's type Fig. 2 Friction coefficient at steady state condition m/s 1.0 m/s Effect of sliding speed on wear. In Fig. 3, the experimental results for pin wear characteristic in the pin on disk tests are presented for sliding speeds of 0.25 and 1.0 m/s. At speed of 0.25 m/s, the wear rate at steady state at condition was µm for RBD palm olein, µm for hydraulic oil and µm for paraffinic mineral oil. While at speed of 1.0 m/s, the wear rate for RBD palm olein, hydraulic oil and paraffinic mineral oil were 18.38, and µm respectively. From the analysis, the wear with lubrication of palm olein and paraffinic mineral oil decreased as the sliding time increased. On the contrary, the wear with lubrication of hydraulic oil increased and showed a huge difference in curve rate, especially at high speed.

4 Applied Mechanics and Materials Vol Wear (micron) PO HO PMO Lubricants' type Fig. 3 Wear of pin at steady state condition m/s 1.0 m/s Discussion From the analysis, the presence of lubricating oil between two metal contacts decreases the coefficient of friction especially palm olein. The stability of coefficient of friction of palm olein proved that palm olein has the ability to stabilize and lessen coefficient of friction by forming a lubricating film which can be easily sheared. From Fig. 3, the lowest value of friction coefficient with lubrication of RBD palm olein was mainly due to the presence of the long chain of fatty acids present in the RBD palm olein, which have the ability to show better lubricating property [7,8] compared to hydraulic oil and paraffinic mineral oil. It is believed that the two contacted surface might have created a metal oxide layer and reacted with fatty acid of palm oil and thus influenced the friction coefficient which resulted in experiment. Palm oil is mainly composed of unsaturated fatty acid, triglycerides, and non-glycerides substance. The high amount free fatty acids chain in RBD palm olein permitted monolayer film formation with the surface that offers sliding surfaces that prevent direct metal to metal contact. The friction coefficient with lubrication of RBD palm olein also decreased as the sliding speed increased. This phenomenon can be explained based on stribeck curve analysis [9]. The stribeck curve is a function of viscosity, speed and load. This graph behavior indicates that the lubricant went through boundary lubrication. Boundary lubrication is characterized by barely adequate fluid in the interface and large surface contact. From the curve, as the relative speed of the surface was increased and the load was constant, the fiction coefficient obtained also decreased. When the sliding speed increases, the temperature of the lubricant at the interface also increases [10]. This phenomenon is attributed to the fact that viscosity of the lubricant decreases and it easily moves with less friction. Fig. 3 shows the wear dominated by the pin at different speeds. It was obvious that the pin lubricated with RBD palm olein created less wear on the pin surface for both low speed and high speed conditions. The material transfer and adhesion of two surfaces were minimized by the presence of thin films, or also called as soap film, by the adsorption of chemical of fatty acid of lubricant between the surfaces [11,12] thus it reducing direct metal to metal contact. All along the experiments, the average wear obtained lubricated with RBD palm olein showed a better result than hydraulic oil and paraffinic mineral, even though there was a slight difference in both speeds. This behavior was probably related to the long chain of fatty acids in the palm oil. Palm olein has the ability to reduce wear due to the higher proportion of long chain saturated fatty acids, leading to inferior cold flow behavior. Conclusion The investigation on tribological behavior of RBD palm olein has been completely obtained using pin-on-disk tester. The result is compared mutually with commercial hydraulic oil and additive-free paraffinic mineral oil. The objectives of this research have been achieved and it could be concluded

5 950 Mechanical & Manufacturing Engineering that RBD palm olein shows a better anti-friction performance compared to additive free paraffinic mineral oil and hydraulic oil in term of friction coefficient and wear at low and high speed. Therefore, palm oil has possibility to be used as lubricant of mating components. Acknowledgement The authors wish to thank the Faculty of Mechanical Engineering at the Universiti Teknologi Malaysia for their support and assistance during this study. The authors also wish to thank the Research University Grant (GUP) from the Universiti Teknologi Malaysia, the Ministry of Higher Education (FRGS-MOHE) and the Ministry of Science, Technology and Innovation (escience MOSTI) of Malaysia for their financial support. References [1] M.A.Chowdhury, M.K.Khalil, D.M.Nuruzzaman, M.L.Rahaman, The effect of sliding speed and normal load on friction and wear property of aluminum, Int. J. Mech. & Mechatronics Eng. 11 (2011) [2] A.A.Nofal, H.Sarhan, Effect of temperature on sliding wear mechanism under lubrication conditions, Int. J. Eng. 5 (2011) [3] T.Hisakado, K. Miyazaki, A.Kameta, S.Negishi, Effects of surface roughness of roll metal pins on their friction and wear Characteristics, Wear 239 (2000) [4] M.Sedlacek, B.Podgornik, J.Vizintin, Influence of surface preparation on roughness parameters, friction and wear, Wear 266 (2009) [5] M.A.Delgado, L.A.Quinchia, C.Galegos, Viscosity modification of different vegetable oil with EVA copolymer for lubricant applicants, Ind. Crops Prod. 32 (2010) [6] S.Syahrullail, K.Nakanishi, S.Kamitani, Investigation of the effects of frictional constraint with application of palm olein oil lubricant and paraffin mineral oil lubricant on plastic deformation by plane strain extrusion, J. Jap. Soc. Trib (2005) [7] M.A.Maleque, H.H.Masjuki, A.S.M.A.Haseeb, Effect of mechanical factors on tribological properties of palm oil methyl ester blended lubricant, Wear 239 (2000) [8] H.H.Masjuki, M.AMaleque, A.Kubo, T.Nonaka, Palm oil and mineral oil based lubricantstheir tribological and emission performance, Trib. Int. 32 (1999) [9] T.Ching-Fang, T.Fort, A study of fiber capstan friction. 1. Stribeck curves, Trib. Int. 37 (2004) [10] T. Savaskan, Z.Azakli, An investigation of lubricated friction and wear properties of Zn 40Al 2Cu 2Si alloy in comparison withsae 65 bearing bronze, Wear 264 (2008) [11] H.H.Masjuski, M.A.Maleque, The effect of palm oil diesel fuel contaminated lubricant on sliding wear of cast irons against mild steel, Wear 198 (1996) [12] B.K.Sharma, K.M.Doll, S.Z.Erhan, Ester hydroxyl derivatives of methyl oleate: tribological, oxidation and low temperature properties, Bioresourse Tech. 99 (2008)

6 Mechanical & Manufacturing Engineering / Experimental Study on the Effect of Different Speeds Applied with Palm Olein Using Pin-on-Disk Tester /

EFFECT OF SURFACE ROUGHNESS PARAMETERS AND SURFACE TEXTURE FOR REDUCED FRICTION. S.Syahrullail 1,N.Nuraliza 1*,

EFFECT OF SURFACE ROUGHNESS PARAMETERS AND SURFACE TEXTURE FOR REDUCED FRICTION S.Syahrullail 1,N.Nuraliza 1*, 1 Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor,