Burnout treatment on plaster mould produced with binder jetting technology: effect of process parameters and geometrical complexity

Binder jetting (BJ) is an additive manufacturing technology that realizes mineral or metallic parts without support material and avoiding critical issues due to thermal phenomena. Because of these benefits, this technology is suitable for rapid tooling applications, as well as for casting process to produce complex moulds made for instance in plaster and organic compound as binder. Regarding the latter application, it is worth noting that chemical reactions can occur when the mould is in contact with molten metal, leading to the formation of gas and therefore porosity in the cast part. To limit this phenomenon, a burnout cycle is usually required before pouring the molten metal. In this research, the burnout temperature and time were investigated, as well as the pre-heating mould temperature before metal pouring in case of simple and complex part geometries. Three different levels of each studied parameters were tested, and the results were analysed in terms of casting defects. Results highlight that a burnout treatment performed at 250 °C for 6 h guarantees the best compromise in terms of casting soundness.