2020 Volume 61 Issue 4 Pages 729-733
In recent years, molds made by additive manufacturing (AM) are increasingly applied to build prototypes and small-quantity casting products. Technological development aiming to use mass-produced castings is advancing with the emergence of high speed AM molding technology. Mass production is expected to improve the potential of the entire casting product, such as the realization of complicated internal structures, thinness, and weight reduction by the improvement of cavity accuracy.
Regarding binders applied to AM sand molding technology, so far organic self-hardening systems are mainly applied and their use is spreading. On the hand, in the case of aluminum alloy castings, the application of hardening system with is required from the viewpoint of the clean working environment. The purpose of this study is to develop an AM sand molding technology utilizing a hardening system with an inorganic binder and artificial sand. The developed hardening system is composed of sand coated with an inorganic binder and inkjettable hardening catalyst. First, the hardening characteristics of the developed hardening system were evaluated using hand molded test pieces, and it was found that it is effective for increasing the initial hardening rate compared with conventional methods. Next, the ability to mold with this hardening system was tested using a binder jetting AM molding apparatus. The gas component generated by heating was measured and the coefficient of linear expansion by the molded test pieces was tested to evaluate the characteristics of the molded test. It was confirmed that harmful gas can be reduced and the mold has low thermal expansion.
This Paper was Originally Published in Japanese in J. JFS 90 (2018) 286–291. Figure 3 and Table 2 were slightly changed.
