Design Strategies for Distortion Compensation and Setters of Binder Jet-printed Parts

Binder jet 3D printing is a process in which a liquid binder is jetted on layers of powdered materials at the appropriate location, followed by sintering. Sintering increases the strength of binder jet 3D-printed “green bodies” through densification, but there is significant shrinkage (up to 22%) and potential distortion. The challenge is to create a pre-deformed CAD geometry that accounts for the shrinkage and warping that occurs during the sintering process caused by factors such as evaporation of the binder, elimination of any pores left from the binder, thermal strain, friction with the build plate, and gravity. Designers can use geometric compensation and supporting structures known as sintering setters to address shrinkage and distortion issues.
The geometric compensation for simple symmetric parts can consist of orthotropic scaling of the green part in x, y, and z directions (i.e., 17%, 17%, 18%).
A sintering simulation software is required to predict the non-uniform distortion for complex geometries. Applying a "negative offset" to the original geometry requires an iterative distortion compensation process. The slightly larger, pre-warped version will shrink and deform to the desired final shape during sintering.
Design guidelines can be sufficient for uncomplicated parts. Shrinkage and distortion of realistic, complex parts depend heavily on part geometry. This presentation provides an overview of design guidelines, the process of designing the green part and sintering setters using a parametric CAD system, and manufacturing simulation software. A real printed part that will demonstrate the Additive Manufacturing Binder Jet design process