Assessment of South African Chromite Sand for Binder Jetting Application

Abstract

Binder Jetting is an Additive manufacturing (AM) technique in which binding liquid is jetted on layers of powdered materials, selectively according to the Computer Aided Design (CAD) model to form a 3D part. One of the applications of binder jetting technology is the manufacturing of sand moulds for sand casting known as Rapid Sand Casting. Silica sand is often used in both Rapid Sand Casting and traditional moulding due to its good refractory properties coupled with its low cost. However, the use of silica sand is associated with some technical limitations, including its high thermal linear expansion and low conductivity, hence it is not appropriate to all casting applications. Chromite sand is used as an alternative refractory material to address the shortcomings of silica sand. This study assessed the suitability of South African Chromite sand for rapid sand casting. Tensile bending and compression test specimens were manufactured from different South African chromite sand samples using a Voxeljet VX 3D printer. The mechanical properties of the specimen produced using binder jetting were compared to those produced by traditional moulding. It was observed that all five printed specimens met the minimum tensile strength of 220 N/cm2 for casting. Hence locally sourced South African Chromite sand can be utilised for rapid sand casting, reducing environmental impact and operational cost.