Not all of the design ingenuity in additive goes toward features of the final part. Some goes to forms destined to be cut away and discarded. In additive, every part feature that projects horizontally from the part is a feature in danger of collapsing as this form is taking shape in one minute layer upon another during the build. The solution is to add support under these features, sometimes in the form of radiuses added to the final form (comparable to adding draft angles to cast parts), and sometimes in the form of supports or stiffeners that last only as long as the build cycle before they are cut away.
Delcam engineers needed cut-away supports for the horizontal floor between the two internal chambers of the manifold part, but they were challenged with how to design these supports. Typical additive support structures—thin metal fins—would have divided the lower chamber into subchambers that would trap the powder, posing the fire hazard mentioned previously. The solution the engineers developed instead was to grown “trees”—tall, slender columns with branching support for strength—in order to hold up this solid floor without impeding the escape of powder.