Optimisation of a Resin-Coated Chromite Sand for Rapid Sand Casting Applications

Abstract

Applications of three-dimensional printing (3DP) to sand casting have been well-established in the last two decades. The preferred raw material is silica (quartz) sand, as it is the most readily available and cost effective sand. However, silica sand as a refractory material has some technical limitations, including high thermal linear expansion, low refractoriness, and thermal conductivity. Therefore, it is not suitable for all castings. Other refractory sand types are available, including chromite sand, which is abundantly available in South Africa. Analysis of the physical and chemical properties of in-laboratory coating of a locally available chromite sand was conducted through known metal foundry tests that provide an understanding of the quality and suitability of the use of chromite sand as a potential substitute for silica material for rapid sand-casting applications. The results of this study will inform the industry about the optimisation of parameters for the manufacturing of a resin-coated chromite sand and its use in additive manufacturing using a Voxeljet VX 1000 printer.

Properties of furfuryl alcohol resins for conventional sand moulding and binder jetting applications

“…5(a) shows the flowability shows that increasing the CSM sulphonic acid catalyst in the chromite sand, in other words using higher amounts, the angle of repose (AOR) increases which in turn decreases the flowability of the sulponic acid coated sand as the two phenomena are inversely proportional to each other. In previous studies by Tshabalala et al [16] and Chauke et al [7] it was observed that when increasing the amount of BJP sulphonic acid catalyst in the chromite sand, the AOR also increased. A high AOR means a low/poor flowability of the sand during printing which is not a desired outcome in BJP.…”

3D Printed (Binder Jetting) Furan Molding and Core Sands—Thermal Deformation, Mechanical and Technological Properties

“…Their significant advantage is their low emissivity, but they are not without disadvantages, including poor knockout properties [13,14], a limited reclamation ability, and unfavorable effects on bentonite (deactivation). Resin-coated sands are a widely used alternative that guarantees a very good surface with minimal defects in gray and ductile iron castings, according to [15][16][17]. Due to their good mechanical and technological properties, as well as the possibility of obtaining cores and complex shape geometries, but also their susceptibility to regeneration, it is expedient to use cores made with binders of organic-type binders [18][19][20][21][22].…”