Foundry sand core property assessment by 3-point bending test evaluation

Abstract

Improved understanding of foundry sand core properties is a key requirement for high precision casting process development. The present work demonstrates the potential to evaluate mechanical and functional sand core properties using precisely acquired 3-point bending test load curve data applying standard bending test geometries.Four organic binder systems have been investigated. Further to bending strength and the elastic modulus, which can be directly derived from the load curves, a load curve pre-treatment to eliminate sample settlement effects was applied for a corrected deflection and stiffness analysis. The consumed mechanical work shows characteristic elastic and plastic work portions until fracture, which are specific for different sand cores, respectively their condition. Dimensionless indicators to quantify core brittleness have been developed based on curve and on work parameters.In general for mechanical evaluations of resin bonded sand cores, visco-plastic effects need to be considered, as for not fully hardened binder systems decreased strength, deflection and work of fracture were observed at lower load speeds.The benchmark results show that the load curve evaluation concept is a suitable tool to analyse foundry sand core properties more sensitively.