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Tribological characteristics comparison of formulated palm trimethylolpropane ester and polyalphaolefin for cam/tappet interface of direct acting valve train system

Rehan Zahid (School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan)
Masjuki Hj. Hassan (Center for Energy Sciences, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia)
Abdullah Alabdulkarem (Department of Mechanical Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia)
Mahendra Varman (Center for Energy Sciences, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia)
Md. Abul Kalam (Center for Energy Sciences, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia)
Riaz Ahmad Mufti (School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan)
Nurin Wahidah Mohd Zulkifli (Center for Energy Sciences, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia)
Mubashir Gulzar (Center for Energy Sciences, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, Malaysia)
Muhammad Usman Bhutta (School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan)
Mian Ashfaq Ali (School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan)
Usman Abdullah (School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan)
Robiah H. Yunus (Department of Mechanical Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia)

Industrial Lubrication and Tribology

ISSN: 0036-8792

Article publication date: 26 June 2018

Issue publication date: 9 July 2018

188

Abstract

Purpose

There is a continuous drive in automotive sector to shift from conventional lubricants to environmental friendly ones without adversely affecting critical tribological performance parameters. Because of their favorable tribological properties, chemically modified vegetable oils such as palm trimethylolpropane ester (TMP) are one of the potential candidates for the said role. To prove the suitability of TMP for applications involving boundary-lubrication regime such as cam/tappet interface of direct acting valve train system, a logical step forward is to investigate their compatibility with conventional lubricant additives.

Design/methodology/approach

In this study, extreme pressure and tribological characteristics of TMP, formulated with glycerol mono-oleate (GMO), molybdenum dithiocarbamate (MoDTC) and zinc dialkyldithiophosphate (ZDDP), has been investigated using four-ball wear tester and valve train test rig. For comparison, additive-free and formulated versions of polyalphaolefin (PAO) were used as reference. Moreover, various surface characterization techniques were deployed to investigate mechanisms responsible for a particular tribological behavior.

Findings

In additive-free form, TMP demonstrated better extreme pressure characteristics compared to PAO and lubricant additives which are actually optimized for conventional base-oils such as PAO, are also proved to be compatible with TMP to some extent, especially ZDDP. During cylinder head tests, additive-free TMP proved to be more effective compared to PAO in reducing friction of cam/tappet interface, but opposite behavior was seen when formulated lubricants were used. Therefore, there is a need to synthesize specialized friction modifiers, anti-wear and extreme pressure additives for TMP before using it as engine lubricant base-oil.

Originality/value

In this study, additive-free and formulated versions of bio-lubricant are tested for cam/tappet interface of direct acting valve train system of commercial passenger car diesel engine for the very test time. Another important aspect of this research was comparison of important tribological performance parameters (friction torque, wear, rotational speed of tappet) of TMP-based lubricants with conventional lubricant base oil, that is, PAO and its formulated version.

Keywords

Acknowledgements

The authors would like to acknowledge the University of Malaya and Malaysian Ministry of Higher Education (MOHE) for funding this research through the High Impact Research Chancellory grant project titled “Development of Alternative and Renewable Energy Carrier”, Grant No. UM.C/HIR/MOHE/ENG/60, University of Malaya Research Grant (UMRG) under the IPPP (Institut Pengurusan Penyelidikan dan Perundingan) Fund Project No. PG200-2016A and International Scientific Partnership Program (Ref no. ISPP#0092) at King Saud University (KSU), Saudi Arabia.

Citation

Zahid, R., Hj. Hassan, M., Alabdulkarem, A., Varman, M., Kalam, M.A., Mufti, R.A., Mohd Zulkifli, N.W., Gulzar, M., Bhutta, M.U., Ali, M.A., Abdullah, U. and Yunus, R.H. (2018), "Tribological characteristics comparison of formulated palm trimethylolpropane ester and polyalphaolefin for cam/tappet interface of direct acting valve train system", Industrial Lubrication and Tribology, Vol. 70 No. 5, pp. 888-901. https://doi.org/10.1108/ILT-06-2017-0156

Publisher

:

Emerald Publishing Limited

Copyright © 2018, Emerald Publishing Limited

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