Effects of metal fillers on properties of epoxy for rapid tooling inserts

Abstract

Metal filled epoxy has been recognised as an alternative material used in rapid tooling application such as core and cavity for injection moulding. The addition of fillers into the metal filled epoxy has proven to increase the epoxy's mechanical performance such as wear, strength, improved machinability and thermal properties. Physical and thermal properties such as density, thermal diffusivity, thermal conductivity and compressive strength were analysed to evaluate the effects of inclusion of metal fillers such as copper and brass particles into the blended epoxy matrix. Brass and copper powders were added separately ranging from 10%, 20% and 30% of its weight into the aluminium filled epoxy mix ratio. Increased density, thermal diffusivity, and thermal conductivity values were evident with a linear trend when both filler compositions were increased from 10% to 30%. Brass and copper density values of 2.22 g/cm3 and 2.08 g/cm3 respectively were recorded at the highest filler composition. Copper fillers with 30% composition in epoxy matrix exhibited the highest average value of thermal diffusivity of 1.12 mm2/s and thermal conductivity of 1.87 W/mK, while the inclusion of brass showed no significant improvement in the properties. Compressive strength increased from 76.8 MPa to 93.2 MPa with 20% of brass fillers and 80.8 MPa with 10% of copper fillers composition. The addition of more metal fillers resulted in a decrease in compressive strength due to the presence of porosity. This study validated previous researchers that fillers enhance mechanical, thermal properties and density of aluminium filled epoxy.