Recycling of Ti-6Al-4V Powder in Metal Binder Jetting

Abstract

Powder in sinter-based metal binder jetting is not fused but only bonded, which in principle ensures full reusability of the unbonded powder. This increases both resource and cost efficiency. In order to explore this potential, this study investigates the effect of powder recycling with regard to handling and thermal influences. For this purpose, a gas atomized Ti-6Al-4V powder is used as a reference powder. It is shown that recycling the Ti-6Al-4V powder four times leads to a minor change in the particle size distribution and an improvement in flow properties. No differences in the average green part densities could be determined, but an increase in their range (from 1 % to up to 7 %). Furthermore, it is demonstrated that the thermal influence due to curing and conditioning (temperatures ≤ 200°C) after printing does not lead to a significant increase in oxygen or nitrogen even after 15 repetitions.