The DTU logo consolidated from stainless steel
powder with the experimental metal 3D printer.
Digital manufacturing of miniaturized component
with micro structures: 3D design (top); micro
component produced by micro 3D printing.
Systematic Approach Framework for Numerical
Model Based Process Development of Metal
Additive Manufacturing.
Ramping up Experimental Capabilities in Metal Additive Manufacturing
The MPP secton at DTU Mechanical Engineering
is ramping up its experimental capabilities in
metal additive manufacturing, commonly known
as metal 3D printing. The majority of research,
development, and innovation in the field of
additive manufacturing world-wide relates to
disciplines supporting metal 3D printing such as
research in process materials, metrology, post
treatment, predictive models, and subsequent
fit and finishing. Due to proprietary closure,
there are no readily available open metal printing
machine tools that are suited for research
in the process itself. To fend open research, the
MPP section has decided to construct a fully
open metal 3D printer of the powder-bed type
with which metal powder can be consolidated
to free-form geometries by means of a highpowered
laser source.
The machine tool is now operational and has
become a valuable asset in the section-wide
joint effort in research excellence in the field
of metal 3D printing. Over the next 2½ years, a
PhD project aims to further develop the experimental
machine tool to allow for new research
directly related to the powder handling, laser
modulation, beam shaping, and the thermal
powder consolidation that takes place inside
this highly digital process. These activities
are concretized in the PAM^2, MADE DIGITAL,
3DIMS and AM-LINE 4.0 research projects
Digital manufacturing of micro products with micro 3D printing
The technology of micro manufacturing scale
feature production by micro 3D printing for the
direct production of miniaturized polymer components
is now a reality. Miniaturized products
with features as small as 50 μm can now be
designed on the computer with a conventional
3D CAD software and then produced by additive
manufacturing.
A specifically designed vat photopolymerization
additive manufacturing (AM) machine suitable
for precision printing has been developed, built
and validated at the section. The AM process
for polymer micro parts production uses the vat
photopolymerization method and the machine
has a manufacturing spatial resolution of 5 μm.
In order to evaluate the AM machine capability,
a test part with features with different sizes
and aspect ratios has been designed. The
printing parameters selected for the optimization
of the machine are exposure time, light
intensity and layer thickness. To have an initial
optimal range of parameter values, a sensitivity
analysis has been carried out prior to the
final experimental plan. The print quality was
assessed in terms of the integrity of the printed
features, the number of printed features with a
square cross section and a decreasing size and
the surface roughness.
The process is capable of producing a surface
with a roughness in the range of 300-800 nm.
The results show the importance of different
factors in micro additive manufacturing processing,
and the need for a full optimization
of micro AM for taking advantage of the true
capabilities of the machine.
The project has been supported by the H.C.
Ørsted Postdoc grant and the Poul V. Andersen
foundation. The research team is composed by
Postdoc Ali Davoudinejad, Senior Researcher
David Bue Pedersen, and Associate Professor
Guido Tosello.
Systematic approach to modelling of metal additive manufacturing
Metal additive manufacturing (MAM) has recently
become a topic of growing intensive research,
fueled by successful cases coming out of large
companies such as GE (jet engine fuel nozzle)
and Siemens (gas turbine blades). To enable a
similar successful generic process development,
but with an added focus on implementability
in Danish industries, a systematic approach
towards MAM has been adopted at the Section
of Manufacturing Engineering (MPP). The ongoing
activities in this field are being sponsored
through Danish and EU funded initiatives such
as Precision Additive Metal Manufacturing
(PAM^2) and MADE Digital, and span across
multiple PhD and postdoc projects.
The goal of a systematic approach is to identify
the most efficient means to generate consistent,
optimum results. From the perspective
of numerical modelling of MAM, it involves
determining the viability of different modelling
procedures based on the experiential application
of clearly defined and repeatable steps
and an evaluation of the outcomes. At MPP,
numerical process models of varying complexity,
participating multi-physics, length- and
time-scales, and reduced orders are being constantly
developed and tested using an intensive
framework shown in the adjacent figure. As a
result, a clear characterization of the computational
resource requirement of each developed
model is combined with a quantified analysis
of the fidelity/accuracy of the model and its
potential for use in process optimization simulations.
The procedure enables identifying a
smart technique for combining the various low,
medium & high fidelity simulation techniques
for MAM in a progressive model based process
optimization.
Contact:
David Bue Pedersen, e-mail: dbpe@mek.dtu.dk
Contact:
Guido Tosello, e-mail: guto@mek.dtu.dk
David Bue Pedersen, e-mail: dbpe@mek.dtu.dk
Contact:
Sankhya Mohanty, e-mail: samoh@mek.dtu.dk
Manufacturing Engineering 33