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Engineering Science in
Additive Manufacturing Reusability of Ti6Al4V powder in LPBF

with little to no examination of the starting material used and to reduce the need for discarding feed material due to
in the printing process. Thus, it is essential to understand powder degradation.
the frequency of feed material reuse and how the reuse of With the importance of knowing how the reuse of
powder impacts the quality of the finished product. 7-11 powder affects the printing process and the part quality,
At present, one method for utilizing powder for multiple much work has been done to investigate the effects
prints while maintaining high quality is the process of with different powders. 27,28 Much of this work has been
sieving and adding a percentage of new powder. 12-14 This focused on the increase of oxygen content and decrease of
process is designed to extend the powder’s lifespan and flowability that occurs due to the oxidation/degradation
maintain its usability without requiring knowledge of its of the powder during the printing process. 29,30 These types
current properties. Thus, if it could be determined whether of characterizations are essential for all powders that are
there are better ways to reuse the powder or know the used when manufacturing with the LPBF process. 31,32 If
extent to which the powder can be used without causing the powders’ flowability decreases sufficiently, defects may
significant defects to the final product, it would lend itself form within the parts, adversely affecting their mechanical
to being able to use the powder at hand for longer while properties. 33,34 With this in mind, there are still areas that
still having reliable manufacturing of the parts. 15-17 More can be expanded upon. In particular, sieving can show
extensive information on how the powder is degraded more information and possible correlation to the other
during the printing process and how the reuse processes powder properties, though this is related to the amount of
can be improved to enable total use of the powder, rather the powder interacting with the laser during the printing
than needing to throw out usable powder, is needed. With process, causing the major defects that can be found in the
the correct information on how to process the powder to used powders.
continue using it or when the powder has passed its reuse The objective of this research was to determine if there
point and needs to be remanufactured, this waste can be is a way to quickly identify the percentage of defects in feed
significantly reduced while also minimizing the amount of material and identify the effects that may have on printed
energy required. 18-22 parts with simple processes. If only simple equipment is
This work aims to determine the reusability of Ti6Al4V available to be used, such as sieves or an angle of repose
(Ti64) powder in a laser powder bed fusion (LPBF) AM tester, then the quality of the powder due to degradation
process. LPBF uses a laser energy source to either sinter or could still be determined. Processes such as sieving are
melt the material that is being printed on a layer-by-layer already conducted during the reuse process and can shed
basis onto the build plate, creating the three-dimensional light on the powder quality without the need for more
(3D) part in the bed of powder while being in an inert characterization. It was hypothesized that the reuse of Ti64
environment, unlike an electron beam PBF, thereby leading powder over an extended number of uses would decrease
to slightly increased level of oxidation. 23,24 This is achieved the printability of the powder and increases the number
by pushing the powder into the build volume with a roller of defects in finished parts, while having a noticeable
at the designated layer height, then adhering it to the layer difference in the powder quality that can be examined with
below by scanning with a laser across the powder in the simple instruments. This will give users of LPBF systems
desired locations for the current layer. The LPBF process the ability to quickly characterize their powder just by
generates waste powder from splatter resulting from the sieving the powder to identify the amount of powder
laser interacting with other particles in the build chamber, that has degraded during the processes, as the powders
thereby forming larger and deformed powder particles. 25,26 should be sieved after every use before the powder is
After a print is finished, it is recollected for reuse in the reused. The addition of testing the angle of repose will
next batch of printing. However, these defective powder give more insight into how the powder is being affected
particles can cause issues with subsequent prints if not by the printing process, while taking small samples from
appropriately addressed, and increase the number of the sieved powder. This will allow for smarter decisions
particles that are not reusable. In the case of powders, on the addition of fresh powder while taking less time to
the recollected powders are sieved before being used examine the powder by using processes that are already
again, with minimal additional processing applied to the being conducted to reuse the powder.
powder, including the mixing of new powder with the used 2. Materials and methods
powder to help minimize the defects of the used powder.
A knowledge gap remains regarding the reusability of Printing was conducted on a 3D Systems DMP 200B SLM
power for LPBF, which must be addressed to enhance the AM system (Rock Hill, SC, USA) using several different
process’s convenience, reliability, and overall efficiency, print settings. These prints were conducted during a

Volume 1 Issue 4 (2025) 2 doi: 10.36922/ESAM025420028