Enhancement of the friction-reducing properties of degraded 20W-50 engine oil by blending with neem and palm kernel oils respectively for application in cold upset-forging of aluminium alloys has been investigated using the ring compression test procedure. Three sets of blends of each of the vegetable oils with the degraded engine oil in the ratios 4060, 5050 and 6040, the engine oil (unused and degraded) and the individual vegetable oils were investigated for friction reduction. Based on the modified empirical formula for friction coefficient determination under the various lubrication conditions, the average values of friction coefficient, µ obtained under the investigated unused engine oil, degraded engine oil, pure neem oil, 40% neem oil, 50% neem oil, 60% neem oil, pure palm kernel oil, 40% palm kernel oil, 50% palm kernel oil and 40% palm kernel oil oils were 0.073, 0.092, 0.068, 0.068, 0.062, 0.060, 0.057, 0.080, 0.058 and 0.057 respectively. Close correlations were observed betweencurves of these friction values andthe standard calibration curves proposed by Male and Cockroft. On comparative basis with degraded oil lubrication condition with average friction coefficient of 0.092, appreciable reduction in friction values were obtained. The lowest average was obtained under 60% palm kernel oil mixed with degraded engine oil. This is attributable to increased viscosity and fatty acid quantity/quality of the investigated vegetable oil. However, based on curves of plot of coefficient of friction against percentage reduction in height, 40% and 50% neem oil in degraded oil could be adjudged the best blend ratios as their coefficients of friction fall with increasing deformation, whereas most of the blends of palm kernel considered in this work demonstrated unstable trends. Best results for neem oil blends with degraded oil could be attributed to the favorable physicochemical properties of the parent vegetable oil.

  INTRODUCTION

Several countries in the world have put in place policies and plans to manage the disposal of degraded oil to protect their environment. Unfortunately the appropriate management of degraded oil is a common problem for many African countries, including Nigeria, where much of the wastes have negative environmental and human health risks because of inadequate systems for collection, storage, recycling, disposal etc. (Bamiro and Osibanjo, 2004).

A common trend in waste management in recent times is recycling of wastes. The benefits of recycling are: less waste, less pollution and a more prudent utilization of precious natural resources (Harrison, 1994). Recycling of used oils will not only reduce harmful wastes in the environment, but will also provide cheap alternative raw materials for industries, particularly the metal-based manufacturing industries.

In metal forming operations generally, friction has been identified as one of the important influential factors whose reduction is one of the main tasks in planning and realization of metal forming processes (Plancaket al., 2012). Of all the methods currently available for reducing friction, the most effective and most employed way is lubrication of interfacial surfaces during deformation (Plancaket al., 2012).

In conventional lubrication practices, the choice is often a mineral oil-based lubricant (Pettersson, 2006). Mineral oils used as lubricants have well-known properties and have been.....