An experimental and numerical approach to formulate binder ink for binder jetting additive manufacturing of zirconia parts

Abstract The choice of binder material to print ceramic components is a challenge in binder jetting additive manufacturing or inkjet printing. The ability to formulate suitable binder materials, especially using bio-based polymers, that provide flexibility and facilitate the rapid development of binder inks is demanded. This is required to meet the increasing demand for a range of materials for various applications. Commonly used binders may contain harmful components that may be left behind, such as carbon residue during the sintering process, thereby affecting the part quality. A novel method for formulating custom binder inks for binder jetting additive manufacturing was developed by studying its rheology, interaction with powder, and green strength. The binder inks developed were investigated for printability using an inkjet printer. The binder strength achieved for a given binder composition was determined. It was observed that increasing concentrations of Carboxy Methyl Cellulose and Chitosan from 0.1% to just about 0.5% increases the binder strength comparable to that obtained using 15% concentration of Polyvinyl Pyrrolidone. Numerical simulations were employed to study the interaction of a binder drop after impact on the powder bed and understand the dynamics of different drop sizes as they penetrated into the powder bed. Through this, a ratio value of ≈0.675 was determined, which was used to establish a relationship between the drop size and the powder layer thickness for this study. The results obtained provide valuable insights, contributing to advancing the binder jetting process, which facilitates optimising and finalising appropriate binder inks and printing parameters to print parts successfully on any binder jetting machine in a very short time.