Investigations on dynamic characteristics of alternate materials for machine tool structures

Abstract

High structural stiffness and high damping are two essential functional requirements of machine tool structures of high-speed precision machine tools to manufacture accurate parts with reduced cycle time. Simultaneously both the attributes can never be accomplished since the conventional metallic materials such as steel and Cast Iron (CI) that is employed in development machine tool structures exhibits higher magnitude of stiffness and with a minimum damping ratio. In recent times, several novel composites such as polymer concrete, cement concrete, cement composites, epoxy granite and synthetic fiber reinforced composites and other advanced materials are preferred in the development of machine tool structures due to their improved mechanical (specific stiffness) and dynamic (damping) properties. Processing methods for conventional materials (foundry operations) and composites reinforced with synthetic fibers, however, involve high production costs and are dangerous to human health and environment. Pebbles can be used to make composites to overcome the above problems. newlineThe main objective of this research is to explore the application of Epoxy Pebble (EP) as an alternate material in comparison with conventional materials towards the development of machine tool structures. Test specimens using epoxy resin and pebble aggregates with fillers have been manufactured. newlineThe pebble: epoxy resin proportions by weight adopted are 65:35, 75:25 and 85:15, with aggregate sizes in the ranges 4-9 mm, 10-12 mm and 13.2-16 mm. Filler of sizes in the ranges 20-250and#956;m, 300-630and#956;m and 710-1000and#956;m were used in this investigation. The matrix material, namely, epoxy resin (LY 556) in combination with hardener (Araldite 951) were identified as binding material. newline