Support-free sintering of 3D printed binder jet copper and stainless steel parts

Binder jet additive manufacturing involves selectively applying a binder, layer-by-layer, to produce green parts, followed by a high temperature sintering treatment. During sintering, green parts are inherently prone to undesired part distortion/sag in the unsupported regions. Traditional methods use 3D printed supports or machined ceramic setters to avoid the part distortion/sag during sintering. We introduce a shape-retaining-stimulus coating that will mitigate/eliminate the need of additional supports during sintering. Simply supported coper and stainless steel green parts of various thickness were evaluated for part distortion. Our experimental results demonstrate that a selective application of the shape-retaining-stimulus coating on 3D printed copper parts with a spanning up to 50 mm, and stainless steel parts spanning up to 33 mm can be sintered without auxiliary supports. Our shape-retaining-stimulus coating produces exceptional results, and the ease of removal makes it an attractive candidate.