Hydrodynamic Characterization of Palm Oil-Based TMP Ester and Coconut Oil Lubricant Blend for Journal Bearing Application

9 pages•Published: August 6, 2026

Inna Salsabila Nazhifah, Syahrullail Samion, Zulhanafi Paiman and Aiman Yahaya

Abstract

The growing demand of biodegradable alternative for mineral-based engine oil has intensified research into vegetable oil-based lubricants capable of operating under hydrodynamic conditions without compromising environmental compatibility. However, many formulations rely on chemical additives to improve viscosity stability and load-carrying performance, potentially reducing biodegradability. This study proposes an additive-free lubricant formulated by blending palm-oil-based trimethylolpropane ester (PO-TMP) with refined coconut oil (CO) and evaluates its hydrodynamic performance in journal bearing applications. Blend C75, containing 75 vol% CO and 25 vol% PO-TMP, was prepared and compared with neat CO, PO-TMP, and SAE 40 mineral oil. Hydrodynamic testing was conducted under a constant radial load of 10 N and rotational speeds from 200 to 2000 rpm using a journal bearing rig equipped with circumferential pressure and temperature sensors, while frictional torque measurements enabled coefficient of friction evaluation. Analytical predictions of minimum film thickness and load-carrying capacity were obtained from the Reynolds equation for short journal bearings. Blending PO-TMP with coconut oil significantly improved viscosity stability without additives, with C75 exhibiting the highest viscosity index (265.8). Despite lower absolute viscosity than SAE 40, C75 generated higher maximum hydrodynamic pressures at all speeds, reduced bearing temperature rise, and maintained the lowest overall friction, achieving an average COF reduction of approximately 25%. The balanced molecular structure of C75 enabled the formation of sufficient film thickness to sustain load-carrying capacity comparable to mineral oil. These findings demonstrate that tailoring complementary vegetable oil structures can enhance viscosity stability, pressure generation, and friction performance while preserving biodegradability, demonstrating C75 as a suitable alternative for mineral oil-based lubricant for journal bearing application.

Keyphrases: biodegradable lubricant, hydrodynamic journal bearing, load carrying capacity, vegetable oil blending, viscosity index

In: Numpon Mahayotsanun (editor). Proceedings of The 11th International Conference on Tribology in Manufacturing Processes & Advanced Surface Engineering, vol 4, pages 113-121.

Links:	https://easychair.org/publications/paper/JP7f
	https://doi.org/10.29007/c6hl

BibTeX entry

@inproceedings{ICTMP2026:Hydrodynamic_Characterization_Palm_Oil,
  author    = {Inna Salsabila Nazhifah and Syahrullail Samion and Zulhanafi Paiman and Aiman Yahaya},
  title     = {Hydrodynamic Characterization of Palm Oil-Based TMP Ester and Coconut Oil Lubricant Blend for Journal Bearing Application},
  booktitle = {Proceedings of The 11th International Conference on Tribology in Manufacturing Processes & Advanced Surface Engineering},
  editor    = {Numpon Mahayotsanun},
  series    = {EPiC Series in Technology},
  volume    = {4},
  publisher = {EasyChair},
  bibsource = {EasyChair, https://easychair.org},
  issn      = {2516-2322},
  url       = {/publications/paper/JP7f},
  doi       = {10.29007/c6hl},
  pages     = {113-121},
  year      = {2026}}

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