A performance-optimized cellular bone implant requires stiffnesses in the order of human bone (1-20 GPa), the cavities should have an open-pored, spherical shape with low particle adhesion and diameters of approx. 500-800 μm. The commercially common systems for the additive laser beam melting (LPBF) process are in principle capable of producing implants with these target parameters, but this potential for filigree structures can only be insufficiently exploited due to the currently widespread contour-hatch scan strategy (CH). The authors developed a combination of conventional CH scan strategy and single vector exposure strategy for the fabrication of cellular structures. Compression specimens out of Ti6Al4V were designed and manufactured using this adapted strategy. The dimensional accuracy, the surface topologies and powder adhesions were determined. Additionally the stiffness of the structures was determined from compression tests according to DIN 50134. It could be shown that the minimum achievable pore size could be reduced due to the more homogeneous and defined energy input by means of the adapted scan strategy, compared to CH scanned specimens. The dimensional accuracy of the structures significantly increased and adhesions were substancially reduced. The Young’s Modulus of the adapted exposed specimens (approx. 3.5 GPa) could be significantly reduced compared to the CH-exposed samples (approx. 6 GPa). The results were realized in a shoulder short stem implant with integrated graded cellular structure.
|Published - 2020
|Fraunhofer Direct Digital Manufacturing Conference 2020
|18 - 19 March 2020
|Degree of recognition