Palm fatty acid distillate as an alternative source for hydraulic oil

Transcription

1 Applied Mechanics and Materials Vol. 315 (2013) pp Online available since 2013/Apr/10 at (2013) Trans Tech Publications, Switzerland doi: / Palm fatty acid distillate as an alternative source for hydraulic oil I.Golshokouh 1, a, J.Y.Wira 2,b, N.A.Farid 3,c and S.Syahrullail 3,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 Mechanical Engineering, Universiti Teknologi Malaysia, UTM Skudai, Johor, Malaysia. a golshokooh@yahoo.com, b wira@ic.utm.my, c farid@fkm.utm.my, d syahruls@fkm.utm.my Keywords: Palm fatty acid distillate, four-ball tribotester, friction coefficient, wear Abstract. This study investigates the physical properties of pure palm fatty acid distillate (PFAD) as a new, clean and renewable source of lubricant and hydraulic oil. This study is done using a fourball tribotester. The experiments are conducted at five different temperatures of 55, 75, 95, 105 and 125 C. The rotational speed was fixed at 1200 rpm, normal load was 40 kg and duration was 1 hour. For evaluating the results, all experiments again were conducted using commercial engine mineral and hydraulic mineral oil and at the end all results were compared together. The results show that PFAD has higher anti friction and anti-wear ability. Introduction There is a growing interest in the use of vegetable oil in industrial properties e.g. hydraulic and lubricant oil. Biodegradable oils can reduce damage and toxics to the environment [1,2]. They are renewable, clean and environmental friendly with unlimited sources. In recent decade, many kinds of vegetable oil such as palm oil, sunflower oil, soy been oil and castor oil have been investigated and the results show that vegetable oils are potential as alternative source of mineral oil in large branches [3]. However, some other researches describe the poor properties of vegetable oils. Vegetable oils have been found to have more oxidation due to polyunsaturation that exits in the fatty acid. PFAD (palm fatty acid distillate) is a by-product of physical refining of crude palm oil roducts and is normally composed of free fatty acids (81.7 %), glycerides (14.4 %), squalene (0.8 %), vitamin E (0.5 %), sterols (0.4 %) and other substances (2.2 %). Physical refining consists of phosphoric acid treatment, deodorization, deacidification and bleaching earth treatment. Deacidification is to remove free fatty acids from the oil. Deodorization is also to remove the odor of the oil. Deodorization and deacidification normally are carried out by using steam under high vacuum. Palm fatty acid distillate is known as a highly odoriferous product. Palm fatty acid distillate also contains some glycerol esters along with minor components of the feedstocks. At room temperature, it is a solid with light brown color and after heating, it turns into brown liquid color. There are several studies about palm oil and application it in metal forming, cold extrusion, lubricant oil, hydraulic oil and biodiesel fuel [4-7]. The aims of this study are to investigate palm fatty acid distillate (PFAD) as an alternative source of lubricant and hydraulic oils. In this experiment, PFAD was used as the lubricant to evaluate their lubricity on the various effects of different. Results showed that PFAD has lower coefficient of friction compared to commercial engine and hydraulic oil. Experimental Details Experimental procedure. Tests were conducted using four-ball tribotester followed the ASTM D4172. The temperatures were varied from 55 to 125 C. After the experiments, the wear scars that occur on the ball bearing were observed. Balls made from chrome alloy steel and made of AISI E were used. Details of the experimental procedure could be found in previous publication [8]. 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-28/05/13,06:36:31)

2 942 Mechanical & Manufacturing Engineering Test Oils. Palm fatty acid distillate (PFAD) was used as a test lubricant. PFAD consists of 93 wt% free fatty acid (45.6 % palmitic, 33.3 % oleic, 7.7 % linoleic, 3.8 % stearic, 1.0 % myristic, 0.6 % tetracosenoic, 0.3 % linolenic, 0.3 % ecosanoic, 0.2 % ecosenoic, and 0.2 % palmitoleic acid) and the rest are triglycerides, diglycerides (DG), monoglycerides (MG) and traces of impurities. For comparison, commercial engine and hydraulic oil were used. Experimental conditions. The tests were carried out at different temperatures of 55, 75, 95, 105 and 125 C of experimental oils. Normal load was 392 N, rotational speed was 1200 rpm and duration was 1 hour. Experimental procedure. Before starting the experiment, the ball pot, top ball holder and ring needed to be cleaned. Then, the machine of each experiment was set up with desired temperature. Three clean balls were placed in the ball pot and the lock ring was inserted around the three balls and in the ball pot. A wrench with 68 Nm force was used to tighten the loch nut around the ball pot. One ball was put to tapper in the collet at the end of motor spindle. Around 10 ml of testing oil was added into the ball pot assembly. The experiment oil must be 3 mm above the tip of the ball. The ball pot assembly was inside the machine and under the spindle on the anti-friction disk. Suitable load test was applied to the load arm. Results and discussions Viscosity. Viscosity is a measure of a fluid internal resistance to deformity by either shear stress or tensile stress of the fluids. Viscosity has a direct relationship with fluid thickness. Internal friction is also related to viscosity. Viscosity is the recognition of private property of liquids. Viscosity index also is used to characterize lubricants and to measure the viscosity with the change temperature. Fig. 1 shows the kinetic viscosity index of palm fatty acid distillate (PFAD), engine (ENG) and hydraulic oils (HYD) at different temperatures. This figure indicates that, viscosity and temperature have reverse impact on the three oils and it means that the fluidity of these lubricants increased with the increase of temperature. Engine oil had a dramatic fall of viscosity between 50 and 75 C but all other experimental temperature points, the engine oil had higher viscosity than other oils. The engine oil had a close trend with the hydraulic and palm fatty acid distillate after 75 C. Also, hydraulic oil and palm fatty acid distillate had a mild downfall with the increase of temperature. Normally, higher viscosity of fluid cases the anti-friction, although large increase in viscosity may cause the lubricant to deteriorate by oxidation or contamination [9] Viscosity (mpa.s) Temperature (Celcius) Fig. 1 Viscosity curve for all the test lubricants. PFAD ENG HYD Flash Temperature Parameter (FTP). Flash point temperature is lowest temperature that liquid can vaporize and inhabit vapor manner. This is done by increasing the heat from the friction between two rubbing surfaces in contact parts. It is normally an advantage point of fluids, especially for lubricant and hydraulic oil because the lubricant thickness layer will be decreased after vaporizing the lubricant oil, where this phenomena causes two parts to be near and be in contact.

3 Applied Mechanics and Materials Vol For these reason, FTP was a recognized limiting factor in the mechanical performance such as cutting and forming tools. PFAD, engine (ENG) and hydraulic oil (HYD) were measured of their FTP in ASTM condition and at different temperatures, with calculation of Eq. 1 (where W is the load in kilograms, and d is wear scar diameter (WSD) in millimeters [10]). All results were compared together to evaluate the flash temperature parameter of PFAD oil. According to Eq. 1, FTP has a direct impact on load and inverse ratio with wear scare diameter. Fig. 2 shows the FTP of PFAD, engine and hydraulic oil in different temperatures. It can be clearly seen that the value of FTP decreased for PFAD, engine and hydraulic oil while the sliding temperature increased. W FTP= (1) 1 4 d FTP PFAD ENG HYD Temperature (Celcius) Fig. 2 Flash temperature parameter for all the test lubricants. Coefficient of Friction. Coefficient of Friction (CoF) is a parameter of describing the ratio of friction force between two or several bodies that are in contact together and usually is the force pressing them together. Fig. 3 shows the relationship between coefficient of friction and temperature for PFAD, engine and hydraulic oil. This figure clearly shows that PFAD oil had higher anti friction ability rather than engine and hydraulic mineral oils. In this experiment, the coefficient of frictions of PFAD and hydraulic oil increased with the increase of temperature but the graph of engine oil had a steady course even with different temperatures. According to the information in the engine oil label, several kinds of additive material were added into the engine oil to reduce friction and wear, which sustains the oil stability to change of temperature. This figure also shows that the hydraulic oil had the lowest anti friction ability and greatest instability versus the temperature change. According to Eq. 1, wear scar diameter (WSD) has an inverse relationship with flash temperature parameter (FTP) and WSD has a direct impact with coefficient of friction. In result, the rise temperature has a direct impact in increasing the friction. For this experiment coefficient of friction was calculated with use of this formula [8]. T µ = (2) W where, µ is a coefficient of friction, T is a frictional torque in kg.mm, W is an applied load in kg.

4 944 Mechanical & Manufacturing Engineering CoF PFAD ENG HYD Temperature (Celcius) Fig. 2 Coefficient of friction for all the test lubricants. Worn Scar Observation. The wear scar of each ball was determined by capturing the picture of the wear scar using specific microscope. The wear scars of PFAD, engine and hydraulic oil were obtained at each test temperature. At temperature 55 C, the lowest wear scar diameter was recorded with a length of mm by engine oil and the highest wear scar diameter with the length of 1.28mm by hydraulic oil. The wear scars on the ball specimen surface of PFAD, engine and hydraulic oil were almost similar and mild abrasive wear could be observed on the ball specimen surface. The wear scar of ball specimen of experimental oil in 75 C was clearly show that the wear scars on the ball surface of engine oil and PFAD oil were mild abrasions and was no more than the wear scar in 55 C. The ball specimen of hydraulic oil had rough abrasion, especially in the middle part of ball surface. For temperature 95 C, the scar shows a mild abrasion on the engine oil ball specimen and rough abrasion on the ball surface of PFAD oil. It is also found that rough abrasion with some small pits in perfect circular wear scar on the ball specimen surface of hydraulic oil. At temperature 105 C, it was found that rough abrasions on the balls specimen of three oils. The circular wear scar of hydraulic oil was bigger than the ones in engine and PFAD oil. At temperature 125 C, it was found clearly that rough abrasion with small pits on ball specimen of PFAD oil and hydraulic oil, and the ball specimen of engine oil had a circle rough abrasion with light pitting corrosion, especially in middle part of ball surface. Conclusion Palm fatty acid distillate, commercial engine oil and hydraulic oil were tested at different temperatures using four-ball tribotester. The results show that palm fatty acid distillate has the lowest coefficient of friction compared to engine and hydraulic oil. The coefficient of friction for palm fatty acid distillate was increased with the increment of the temperature, however, the coefficient of friction for engine and hydraulic oil were almost steady with the increment of temperature. Wear scar observation showed that all test lubricant were capable to reduce wear at low temperature but the wear condition become worse when the temperature increased. 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.

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6 Mechanical & Manufacturing Engineering / Palm Fatty Acid Distillate as an Alternative Source for Hydraulic Oil /