Tools & Technologies
By Blake N. Johnson
Advanced fluid dispensing drives 3-D printing innovations
3-D printing is an actively growing additive
manufacturing paradigm driven
by the ability to minimize waste, personalize
products and fabricate parts
defined by complex three-dimensional
geometry.
Thus, researchers are examining various
additive manufacturing processes.
However, extrusion-based 3-D printing
is an especially attractive option due to
its compatibility with an expansive set of
input materials, high fabrication speed,
reasonable printing resolution and ability
to integrate multiple materials. Extrusion-
based 3-D printing is particularly
promising in the healthcare sector
for regenerative medicine applications,
the pharmaceutical industry for drug
discovery applications, and the industrial
engineering community for ergonomics
applications.
For years, the dispensing industry
has supported various sectors, such
as the electronics, packaging and
automotive industries, in the area of
adhesive and sealant dispensing. The
development of precision-dispensing
solutions for extrusion-based 3-D
printing applications has become a
critical focus area. However, the task is
challenging because the input materials
vary widely with respect to viscosity and
curing characteristics. In addition, the
dispensing path and time interval differ
among applications and the resolution for
extrusion-based 3-D printing is directly
related to the precision and resolution of
material extrusion.
Three primary components provide
the basis for all extrusion-based 3-D
printing processes: motion control, imaging
and dispensing systems. Highly
advanced motion control and imaging
systems already support CNC milling
processes, so innovations in dispensing systems currently are driving the evolution
of extrusion-based 3-D printing
processes.
Such dispensing innovations are occurring
in several areas, including dynamic,
small volume, rapid and noncontact
dispensing.
One innovative solution to print materials
that change viscosity throughout
the manufacturing process is the Ultimus
V High Precision Dispenser
from Nordson EFD. The Ultimus V dynamically
adjusts the dispensing pressure
to maintain a constant dispense rate. For
flexibility, dynamic adjustment of the
dispensing pressure can be conducted
based on either the dispense time or the
number of dispense events. The shot size
stays consistent regardless of changes in
fluid viscosity, and the product has an
external personal computer interface for
data input. Simultaneous display of all
dispensing parameters simplifies process
control.
Additionally, Nordson EFD's PICO
Pμlse jet valve can accommodate
the printing of low-viscosity fluids.
To address this challenge, a creative
noncontact printing approach is being
used based on material deposition via
continuous jetting of microdroplets as
small as 500 pL (one picoliter is equal
to 1×10-12 liters) at frequencies up to 1
kilohertz. Fine-tuning of the dispense
pulse time can also be adjusted
in increments of 10 μs. Variable
stroke makes it possible to set exact,
repeatable deposit quantities, and the
machine can adjust to handle highviscosity
fluids.
Although the future of extrusionbased
3-D printing is still unpredictable,
it is clear that advances will be linked
closely to innovations such as these in
advanced fluid dispensing.
Blake N. Johnson is an assistant professor in the Department
of Industrial and Systems Engineering at Virginia Tech and a
member of IISE's Young Professionals group.