The possibility to fabricate metallic parts by material extrusion additive manufacturing of highly-filled polymer (MEAM-HP) with low-viscosity feedstock has been demonstrated in this study. Quality parts were successfully printed using a laboratory plunger-based printer and two feedstocks consisting of stainless-steel powder blended with two different compositions of organic binders made of ethylene-vinyl acetate (EVA), paraffin wax, and stearic acid. Using the first feedstock, containing 5 vol. % EVA, dimensionally stable parts were printed only for a feedstock temperature of 70 °C, while with the second feedstock, containing 10 vol. % EVA, stable parts were printed within a larger feedstock temperature range of 70 to 140 °C. The minimum feedstock temperature was defined at 85 °C to guarantee sufficient adhesion between beads and limit binder shrinkage during the cooling. Using this optimal process parameter, complex-shape parts were successfully printed confirming that complex surfaces, bridging, and overhang structures can be produced using low-viscosity feedstock without help of supports.

1.
ISO/ASTM
(
2021
). 52900:2021:
Additive manufacturing-General principles-Fundamentals and vocabulary
.
West Conshohocken, PA
,
ASTM International
.
2.
Zhang
,
J.
and
Y.-G.
Jung
, "2. Additive Manufacturing Processes and Equipment",
Additive Manufacturing-Materials, Processes, Quantifications and Applications
,
Elsevier
, (
2018
)
3.
H.
Ye
,
X.Y.
Liu
and
H.
Hong
, "
Sintering of 17-4PH stainless steel feedstock for metal injection molding
",
Mater. Lett.
,
62
(
19
), pp.
3334
3336
(
2008
).
4.
A.
Mostafaei
et al, "
Binder jet 3D printing–Process parameters, materials, properties, and challenges
",
Progr. in Mater. Science
,
119
,
100707
, (
2021
)
5.
L.
Waalkes
, et al, "
Feasibility study on piston-based feedstock fabrication with Ti-6Al-4V metal injection molding feedstock
",
Addit. Manuf.
,
35
:
101207
, (
2020
).
6.
ASTM
(
2016
).
D3418-15: Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry
.
West Conshohocken, PA
,
ASTM International
.
7.
ASTM
(
2008
).
E1131: Standard Test Method for Compositional Analysis by Thermogravimetry
.
West Conshohocken, PA
,
ASTM International
.
8.
J. M.
Dealy
and
K.F.
Wissbrun
, "
Melt rheology and its role in plastics processing: theory and applications
",
Springer Science & Business Media
, (
2012
).
9.
Hausnerova
, et al, "
Rheological properties of gas and water atomized 17-4PH stainless steel MIM feedstocks: Effect of powder shape and size
."
Powder Technol.
,
312
, pp.
152
158
, (
2017
).
This content is only available via PDF.