Analysis of effective thermal conductivity for mineral cast material structures with varying epoxy content using TPS method

A. Selvakumar,P. V. Mohanram

doi:10.1590/s1516-14392012005000184

Abstract

Conventionally, cast iron is the material used for high speed machine tool structures. As an alternate material to improve the structural properties, composite materials are being used, which are known to exhibit excellent thermal and mechanical properties. While selecting an alternate material, thermal conductivity is an important thermo physical property of the material that should be studied. A resin composite material has a lesser thermal conductivity and its thermal properties vary with the composition of the mixture. A material with lower thermal conductivity will have higher heat concentration within the structure, which may result in structural deformation. In this analysis, epoxy granite, a material which is tested to exhibit excellent mechanical properties has been selected to study its thermal properties. Tests are carried out using Transient Plane Source (TPS) method, on eight samples with varying volume fraction of epoxy content in the range 10-24%. It is observed that, the effective thermal conductivity decreases with an increase in epoxy resin content in the mixture because the resin content increases interfacial resistance between particles. Hence, lower epoxy content in the mixture that maximizes the effective thermal conductivity while maintaining good mechanical properties is to be selected.

Highlights

In high speed machine tools, the material used in its structure play a major role in the productivity of the machine and the accuracy of the parts manufactured
Trial and error method is adopted to determine the slope corresponding to the selected temperature, such that the values of thermal conductivity calculated from the slope is repeated within 2% error limit[10,12]
The measurement of effective thermal conductivity for eight samples with epoxy content varying in the range 10-24% is presented

Summary

Introduction

In high speed machine tools, the material used in its structure play a major role in the productivity of the machine and the accuracy of the parts manufactured. They influence the static and dynamic stiffness, mass, modal and thermal properties of the machine tools. Cast iron is the most preferred conventional structural material used in manufacturing precision machine tool structures, as it has excellent damping properties which minimize the dynamic loads and its high quality to price ratio. Studies indicate that machine tool structures having low mass and high damping compared to conventional materials improves productivity[1,2]. Recent research on high speed precision machine tool structures aims at developing an alternate composite material which exhibit good thermal characteristics along with its excellent mechanical properties

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Conclusion