Improvement of manufacturing accuracy of graded Ti-6Al-4V BCC lattice structures by local laser power adaption

Abstract

Additive Manufacturing by laser powder bed fusion (PBF-LB/M) enables the manufacturing of metallic implants with graded lattice structures, adapting the porosity and stiffness of the implant with cortical and trabecular bone for improved osseointegration. One drawback is the manufacturing accuracy of graded lattice structures due to deviating process strategies. Minimal structures with diameters < 150 µm require low energy input to avoid overmelting. Conversely, larger structures (> 200 µm) are then prone to insufficient melting and require higher energy input. This prevents a combination into one graded structure using standard strategies, which can result in deviations of up to 50%. Investigations show that adjusting the energy input at down-skin surfaces enables a more precise manufacturing for graded BCC lattice structures (ranging from 100 – 300 µm) without severe compromise for one size region. Furthermore, this approach also reduces the deviation for specific structure sizes to less than 2%.