Extraction and physicochemical characterization of cashew nut-shell liquid in metal forming

Abstract

Effective lubrication during metal working is critical to mitigating undesirable tool wear and poor surface finish of formed components. This paper investigated the physicochemical characteristics of cashew nut-shell-liquid (CNSL) with a view of determining its suitability for the development of an eco-friendly lubricant used in metal forming. The cashew nut shell oil (CNSO) was extracted by soxhlet method and characterised to determine its physicochemical properties including density, free fatty acid (FFA), and viscosity. In addition, the saponification value, iodine value, pH, flash point and friction coefficient were determined using relevant analytical tools. The results showed that CNSL yield from soxhlet solvent extraction is 45.6%, which is adjudged to be relatively substantial with regard to other extraction processes. Furthermore, the CNSL exhibited critical lubrication characteristics in terms of density (0.94 g/cm3), moisture content (3.96%), acid value (11.32 mg.KOH/g), FFA (3.7%), ester value (127.92 mg.KOH/g), saponification value (139.24 mg.KOH/g), pH value (4.61), iodine value (40.21 gI2/100 g), viscosity at 100 oC (14.12 Pa.s), friction coefficient (0.001) and flash point of 286.63 oC. Given these outcomes in comparison with commercial Chevron soluble oil, it is concluded that CNSL is suitable for use as a viable metal forming lubrication fluid.