Experimental Evaluation on Lubricity of RBD Palm Olein Using Fourball Tribotester

Abstract

Tribology is defined as “the science and technology of surface interacting in motion” . Thus it is important for us to understand the surface interaction when they are loaded together as to understand the tribology process occurring in the system. The physical, chemical and mechanical properties not only cause the effects to the surface material in tribology behavior but also the near surface material. Apart from that, on the surface of the bulk material, lies a layer formed as a result from the manufacturing process. This deformed layer is covered by a compound layer resulting of chemical reaction of metal with the environmental substance such as air. In addition, the machining process such as cutting lubricants to be trapped may also cause the deformed regions of the surface. The regions on the surface material can critically affect both friction and wear of metals. In addition, the forces which arise from the contact of solid bodies in relative motion also affect both friction and wear. Thus, it is important for us to understand the mechanics contact of solid bodies in order to evaluate the friction and wear on solid bodies. Solid bodies are subjected to an increasing load deform elastically until the stress reaches a limit or maximum yield stress then deform plastically (Gohar and Rahnejat, 2008). Friction is known as resistance to motion. Friction can be categorized into five types; which are dry friction, fluid friction, lubricated friction, skin friction and internal friction. The friction forces are divided into two types; static friction force which is required to initiate sliding, and kinetic friction force which is required to maintain sliding. Coefficient of friction is known as the constant of proportionality in which the typical two materials may be similar or dissimilar, sliding against each other under a given set of surfaces and environmental conditions (Arnell and Davies, 1991). The first laboratory test device for determining lubricant quality was known as fourball tribotester is proposed by Boerlage in the year of 1993 (Ivan, 1980). The concept of friction for this machine is three stationary balls pressed against a rotating ball. The quality and the characteristics of the lubricant were established by the size of the wear scar or the seizure load and the value of friction obtained. The main elements of fourball machine are vertical driving shaft which hold the moving ball at the lower end with conical devices. Besides that,