Advanced lattice support structures for metal additive manufacturing

Metal additive manufacturing (MAM) of complex parts with overhangs typically requires the use of sacrificial support structures to hold the part during the process. This structures which are built simultaneously with the part, anchors the overhang geometry to the base plate and prevent distortion/curling resulting from thermal stresses. They are necessary, but add constraints to the geometries that the processes can make. The design and selection of support structure can influence the manufacturability of complex metal parts, material and energy utilization, manufacturing time and cost. This study takes a new step on the design and manufacturing a more efficient support through the novel application of lattice structures with very low volume fraction. Experiments were conducted in direct metal laser sintering (DMLS) machine using titanium alloy Ti6Al4V powder. Experimental results revealed that the type of structure, volume fraction and cell size are the main factors influencing the manufacturability, amount of support, and built time of lattice support structures. Lattice supports with very low volume fraction up to 8% were built, saving significant amount of materials used in the support while reducing built time of making MAM parts.

► A novel lattice support structures for metal additive manufacturing is proposed.
► Low volume lattice supports are faster to build and efficient for material saving
► Residual stresses which remained in the part was released in the form of deflection
► Supports having bigger gap involve greater deformation and manufacturing failure
► Very thin lattice structures are too fragile to be consistently manufactured in SLM.