Michael W. Barclift

Cost modeling for Powder Fusion (PBF) has traditionally treated the material feedstock
as a fixed cost. Given that a built-up geometry in PBF must be in a bed filled with surrounding
powder, the material feedstock is susceptible to satellites, chemical contamination, and dissimilar
properties with each subsequent reuse (recycling). In this paper, we extend an existing PBF cost model and
propose a new financial depreciation model for reused metal powders. Using… Show more

Cost modeling for Powder Fusion (PBF) has traditionally treated the material feedstock
as a fixed cost. Given that a built-up geometry in PBF must be in a bed filled with surrounding
powder, the material feedstock is susceptible to satellites, chemical contamination, and dissimilar
properties with each subsequent reuse (recycling). In this paper, we extend an existing PBF cost model and
propose a new financial depreciation model for reused metal powders. Using Sum-of-the-Years
Digits depreciation, powder feedstock is valued as a function of build cycles endured by the
material feedstock. A case study is presented on two example parts in Direct Metal Laser
Sintering (DMLS). Results show that cost models using a fixed material cost can undervalue
build jobs with a high value virgin powder by as much as 3-11% or 13-75% depending on the
material and its maximum build cycles in PBF. Show less

In Objet’s PolyJet process, part layers are created by selectively inkjetting photopolymers
onto a build substrate and then cured with ultraviolet lamps. With an eye towards using PolyJet
as a manufacturing process to fabricate end-use products, the authors examine the sensitivity of
part material properties to variation in process parameters. Specifically, a design of experiments
is conducted using a full-factorial design to analyze the effects of three parameters on the… Show more

In Objet’s PolyJet process, part layers are created by selectively inkjetting photopolymers
onto a build substrate and then cured with ultraviolet lamps. With an eye towards using PolyJet
as a manufacturing process to fabricate end-use products, the authors examine the sensitivity of
part material properties to variation in process parameters. Specifically, a design of experiments
is conducted using a full-factorial design to analyze the effects of three parameters on the
specimens’ tensile strength and tensile modulus: the in-build plane part orientation (X-Y), the
out-of-build plane part orientation (Z), and the distance between specimens. Results show that
part spacing has the largest effect on the tensile strength, but the three parameters produced no
statistically significant effects on the tensile modulus. Orienting specimens in XZ orientation
with minimal part spacing resulted in the highest tensile strength and modulus. Whereas,
orienting specimens in the YZ orientation at the farthest part spacing led to the lowest
mechanical properties. Show less