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Single-Pass Digital Production Printing and Deposition
Single-Pass Digital Production Printing and Deposition
Single-Pass Digital Production Printing and Deposition
M A N A G E M E N T
Digital inkjet technologies are
increasingly being adopted as an industrial
fabrication method for depositing new
exotic materials. However, inkjet has
found success over the years in numerous
c om m o d it y p r o d u c t-f a b r i c a t i o n
applications as well.
This article reviews the various inkjet
technology types and provides pros and
cons of thermal, piezo and continuous
inkjet in industrial-use applications. We’ll
look at the various criteria, from economic
considerations to process practicality, to
consider when assessing if digital fabrication
techniques are appropriate. Finally, the
article offers several commercial examples,
ranging from high-end electronic device
fabrication to digital coatings and
commercial food decoration.
The use of inkjet as a commercially
viable method for applying text and
graphics onto a variety of print media
is well established. There are numerous
examples of inkjet printing machines,
ranging from small office/home office
(SOHO) applications (typically thermal
inkjet) to mid- and high-end commercial
in true industrial operations. Much of
what has been disclosed has focused on
device fabrication for electronic materials;
conducting traces, logic devices, RFID, all
kinds of displays and solar panels.
Inkjet has received little attention in
several important, but less prominent,
applications. This may be a result of inkjet
use in industrial applications, which often
requires custom or unique system design.
Furthermore, companies often view
these pioneering efforts as a competitive
advantage and aren’t willing to publicize
their use.
Industrial Environments
Before discussing inkjet’s attributes,
it’s useful to consider the term “industrial
inkjet.” There are many examples of
commercial inkjet printing systems. These
Commercial inkjet printing systems
include the SOHO, direct-mail and super-
wide graphic printing systems. Industrial
applications generally:
¦Do not use standard media
¦Are part of a process to fabricate or
manufacture a product
¦Are an inline process
¦Have high volume
¦Aren’t usually print-for-pay
¦Are custom-configured or purpose-
built
¦Are manned by lower-skilled
operators
¦Operate in dirty environments
¦Are used in 24/7 operation with
little operator intervention
There are numerous examples of inkjet
systems used for coding and marking.
The use of inkjet as a commerically viable method for
applying text and graphics onto a variety of print media is
well established ... [but] Inkjet has received little attention
in several important, but less prominent, applications.
Single-Pass Digital Production Printing and Deposition
M A N A G E M E N T
Digital inkjet technologies are
increasingly being adopted as an industrial
fabrication method for depositing new
exotic materials. However, inkjet has
found success over the years in numerous
c om m o d it y p r o d u c t-f a b r i c a t i o n
applications as well.
This article reviews the various inkjet
technology types and provides pros and
cons of thermal, piezo and continuous
inkjet in industrial-use applications. We’ll
look at the various criteria, from economic
considerations to process practicality, to
consider when assessing if digital fabrication
techniques are appropriate. Finally, the
article offers several commercial examples,
ranging from high-end electronic device
fabrication to digital coatings and
commercial food decoration.
The use of inkjet as a commercially
viable method for applying text and
graphics onto a variety of print media
is well established. There are numerous
examples of inkjet printing machines,
ranging from small office/home office
(SOHO) applications (typically thermal
inkjet) to mid- and high-end commercial
in true industrial operations. Much of
what has been disclosed has focused on
device fabrication for electronic materials;
conducting traces, logic devices, RFID, all
kinds of displays and solar panels.
Inkjet has received little attention in
several important, but less prominent,
applications. This may be a result of inkjet
use in industrial applications, which often
requires custom or unique system design.
Furthermore, companies often view
these pioneering efforts as a competitive
advantage and aren’t willing to publicize
their use.
Industrial Environments
Before discussing inkjet’s attributes,
it’s useful to consider the term “industrial
inkjet.” There are many examples of
commercial inkjet printing systems. These
Commercial inkjet printing systems
include the SOHO, direct-mail and super-
wide graphic printing systems. Industrial
applications generally:
¦Do not use standard media
¦Are part of a process to fabricate or
manufacture a product
¦Are an inline process
¦Have high volume
¦Aren’t usually print-for-pay
¦Are custom-configured or purpose-
built
¦Are manned by lower-skilled
operators
¦Operate in dirty environments
¦Are used in 24/7 operation with
little operator intervention
There are numerous examples of inkjet
systems used for coding and marking.
The use of inkjet as a commerically viable method for
applying text and graphics onto a variety of print media is
well established ... [but] Inkjet has received little attention
in several important, but less prominent, applications.
Inkjet’s Applications, Advances
and Advantages as an Industrial
Manufacturing Method
printing systems (predominately using
piezo technology).
To date, there has been much discussion
but little disclosure relative to using inkjet
systems are generally available, and used for
print-for-pay applications. These printers
jet onto known traditional media, and are
often stand-alone devices.
By Dr. Rich Baker, Director of Business Development, FUJIFILM Dimatix Inc. USA
and Ed Chrusciel, Marketing Director, FUJIFILM Dimatix Inc. USA
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First Quarter 008 | 1
Ink Jet Technologies
Continuous Drop on Demand
Piezoelectric Thermal
These arguably fall into the realm of
“industrial inkjet,” but are secondary to the
actual production or product fabrication.
“Industrial inkjet” is a term used to define
inkjet technologies that are an integral part
of the product manufacturing process.
Inkjet Printing Technology
Inkjet is broadly divided into two major
technologies: Continuous Inkjet (CIJ) and
Drop-on-Demand Inkjet (DOD). DOD
is further divided into Thermal and Piezo.
(See Figure 1)
CIJ Attributes
Continuous inkjet employs a stream of fluid
that passes over two charge plates: The first
charges the droplets and the second defects
them into a gutter or onto the substrate.
The ink types used in this technology
are typically dye-based, solvent-based inks
for multi-defection, single-stream versions
(typically used in small character date
coding), and dye-based, water-based ink
for binary-deflection, multi-nozzle arrays
(typically used for document printing).
The print speed, and subsequently the
line speed, for these system types are high,
but there are challenges in developing inks,
especially with the pigments.
Attributes of DOD Thermal
DOD Thermal Inkjet (sometimes referred as
“Bubble-Jet”) uses heating elements situated
close to an array of nozzles. To actuate the
nozzle, the associated heating element rapidly
heats. This vaporizes components in the ink
(typically water) in proximity to the heating
element, producing a bubble that forces ink
out of the nozzle. Upon cooling, the bubble
collapses and ink is drawn into the channel by
capillary action ready for the next actuation.
This technology is predominant in
home-office printers. The inks are limited
to fluids that have an evaporable content
(typically water). The jetting frequency and
device lifetime also are limited. The major
benefit is the unit cost, although this may
not be economical when considering the
number of head replacements needed over
the system’s lifetime.
Attributes of DOD Piezo
Piezo inkjet (sometimes referred as “Impulse
Jet”) is a technology that uses the deforming
nature of piezo-electric ceramics to impart
pressure pulses to defined-ink chambers.
These pressure pulses cause droplets to be
ejected when they encounter the nozzle’s
small aperture.
There are several internal architectures
employed by various vendors (shared
wall and individual channels) and several
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Figure 1: Inkjet Technologies
0
1
2
3
4
5
6
7
8
9
1011121314151617181920
Frequency (kHz)
Figure 2: Line speed vs. jetting frequency for various in-process addressability
20040060080010000100 dpi
200 dpi
400 dpi
600 dpiLine Speed (Ft/min)
Jet Trajectory
Error
0
Nozzle Placement Error
Drop Placement Error
Figure 3: Effect of nozzle placement and Jet trajectory on drop placement
Figure 4: Single jet firing vs. all jets firing — showing minimal cross-talk
| SGIA Journal ¦
First Quarter 008
methods of exciting the piezo materials
(extension mode, shear mode and bend
mode). Some head configurations, owing
to the internal architecture, allow all jets to
be fired simultaneously, while others must
use a series of alternating nozzles. Some
have benign ink-fluid paths, while others
have electrical contacts in the fluid paths.
However, in general, Piezo inkjet print-
head technologies can fireat medium jetting
frequencies (10-30 kHz), and tolerate a
wide range of ink chemistries. One of the
shortfalls for some ink chemistries is nozzle
open time. Since these devices do not eject
drops unless actuated, fast-drying inks will
quickly dry in the nozzles and occlude the
jets. For reliable operation, care must be
taken to design appropriate capping and
maintenance stations.
Inkjet Technology and Application
Criteria
For an industrial application to be successful,
theuserneedstoreviewmanyinterdependent,
physical,technical, operationaland economic
criteria to assess suitability. Successful
implementation of industrial inkjet
technology in a manufacturing process is
determined by the type of inkjet technology
used and the resulting system architecture.
Other important considerations
include:
¦
Application suitability
¦
Print-head technology suitability
¦
Systems integration
Application Suitability
Choosing inkjet as an industrial process
should be thoughtfully considered. Major
factors that determine if the application is a
fit with inkjet are application requirements
for data variability and product run-length.
The economic factors of applications
that fall into these criteria are often difficult
to determine, as the costs savings aren’t in
direct cost-per-piece comparisons, but in
savings from labor, secondary processes,
inventory, scrap and turnaround times.
In general, if there is a suitable alternate
method of imaging, inkjet may be lower
quality, technically more challenging
and more expensive (both in capital and
ongoing run costs).
Applications in which inkjet enables a
new process methodology or (ideally) is the
only viable production method are much
more compelling (i.e., inkjet adds value
versus decreasing cost).
Questions to address when considering
inkjet:
¦
Is the use of inkjet a new process step
or is inkjet going to replace a current
method of production?
¦
Why is inkjet being considered?
¦
What are the technical and
economic benefits?
¦
Is there an inkjet ink or fluid
available?
¦
Is the inkjet quality acceptable?
¦
Does this process add value, reduce
cost or reduce time?
¦
Is there a place in the process where
inkjet is essential?
If any of these questions result in
reservations or doubt, carefully review
your plans to use inkjet.
Print-Head Technology Suitability
In determining if inkjet is suitable for
a specific industrial application, print
head technologies and options need to
be reviewed. The following criteria is a
guide of the various inkjet parameters that
should be considered and compared:
¦
Ink options - How robust is the
jetting component with the target
chemistry? Will the head jet the fluid
that your process requires?
¦
Print head robustness -How resistant
is the physical construction of the print
head to the operating environment in
which you expect to be jetting?
¦
Number of nozzles and packing
density – Based on your required
image quality and the jet density
of the base print head module, how
large is the required head cluster
going to be? This affects the precision
requirements of your substrate
motion and the jet quality of the
inkjet device.
¦
Jetting frequency – At the desired
line speed and required print
addressability, does the proposed
jetting technology meet your
requirements? (See Figure 2)
¦
Straightness – Since most industrial
applications are trending toward
single pass, high-jet straightness is
essential for good quality imaging
and high resolution printing. Simple
calculations of jet straightness,
drop mass, product standoff and
product velocity will determine if the
print head can image the required
resolution for high-quality imaging.
(See Figure 3)
¦
Drop mass and variations – It’s
essential to understand the acoustic
properties of the jetting process
and the frequency effect on drop
mass. Inkjet structures typically
have variable-mass outputs as they
progress through the frequency
range. In some cases, increasing the
line speed results in improved jetting
performance.
¦
Drop velocity and uniformity – Like
drop mass, drop velocity also varies with
jetting frequency. Mass and velocity can
be affected by a phenomenon known as
“cross-talk.” Cross-talk is the measured
effect on mass and velocity when a jet’s
performance varies, depending upon
if it is fired alone or simultaneously
with other jets (typically adjacent). (See
Figure 4)
¦
Drop-mass modulation – Inkjet
heads are predominantly binary.
That is to say, you either produce a
drop or not. It is not easy to create
grey levels. When evaluating print
heads with the ability to produce
variable drop masses, drop-velocity
control is also essential. The smaller
drop and the larger drop must land
on the substrate in the appropriate
location. To do this, their drop
velocities need to be matched. (See
Figure 5, page 34)
¦
Head life – Head life is a function
of the print head’s ruggedness,
fluid jetted, environment and
maintenance procedure. If a print
head requires frequent wiping,
care must be taken to design the
maintenance protocol or choose a
print head with a robust nozzle plate.
¦
Throughput and output –
Published performance specifications
of inkjet technologies tend to vary
from vendor to vendor. A commonly
adopted evaluation metric is
“nanogram kilohertz.” To calculate
this, multiply the nominal drop-
mass by the jetting frequency and
then de-rate that by any limitations
in the duty cycle. If all jets cannot
fire simultaneously, de-rate by the
alternating sequence (e.g., divide by
3). If the head self-heats, de-rate by
the recommended duty cycle (e.g.,
30 percent). This will show the raw
throwing power of the device and
provide a good metric for comparing
technologies.
¦
Price and economics – A system’s
economics reach far beyond the
simple print head technology cost.
Downtime, operator intervention,
scrap, run costs, maintenance costs,
product quality and marketability
are all factors, and should be
considered holistically.
Systems Integration
The decision to either act as your own
system’s integrator or use the services of
an inkjet integration specialist will come
down to economics, abilities and interest.
If you expect to integrate inline equipment,
it is generally better to have the system
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Figure 5: Three drop masses from a common nozzle
plate showing uniform velocity and drop placement
Dimatix VersaDrop TM
designed, fabricated and supported by an
external group. Additional considerations
include:
¦
Substrate motion – How accurate is
the current substrate motion? Does
the current process require additional
engineering efforts to control the
substrate motion for the intended
application? Whose responsibility is
it?
¦
Print head cluster mechanical
tolerances – Do these fall within
the acceptable system error
allocations? What is the field repair
or replacement strategy? Is it a drop
in replaceable unit or will it require
adjustment?
¦
Print head cluster mounting
– Whose responsibility is it? Can it
be done with appropriate precision?
What about product avoidance
features and park-and-tend stations?
¦
Ink properties – What are the
nozzle open time and maintenance
requirements? Will the substrate
need pre- or post-treatment? Will
the ink cure or dry in the current
process? If the system and ink are
not supplied by the same supplier,
who is responsible for the systems
operation, support and warranty?
¦
Ink lay-down protocol – Do the
ink properties vary with lay-down
order, cure protocol and substrate
variations?
¦
Data path – What are the data
path’s needs: Fixed imaged, repeated-
fixed image sets, variable images,
contiguous images or multi-laned
product images? The considerations
continue, but it’s appropriate that
these questions be addressed by the
end–use customer and integrator.
The relationship between an
industrial user and its systems
supplier is much more of a long-term
partnership than an initial sale.
The end user is going to rely on the
integrator to ensure the production
line is running on a high availability.
High-quality engineering, technical
competence in all the disciplines and
operational support is mandatory.
¦
External I/O – Typically in industrial
environments, the inkjet process
is part of a production process. At
a minimum, the inkjet controller
will need to have the capability of
communicating its status (such as
printing, not printing and alarm)
to the line PLC. In some cases, the
inkjet controller may be required to
provide line control, such as scrap
gate actuation, UV lamp shutter
actuation or line stop.
Industrial Application Examples
Successful applications are those in which
all of the technical criteria are met and the
economics make sense. The following are
examples of successful industrial inkjet:
Applications Key Attributes
Food Decoration Non-contact, variable data
Liquid Crystal Replaces spin coating for
Displays large displays, non-contact
LEP Displays Precision deposition
Flooring ceramics Variable imaging
and laminates
Wood graining Variable imaging
Scratch-resistant Fast setup, non-contact
coatings
Electronics Replaces costly multi-step
deposition process
Specialty Textiles Variable imaging, embedded
information
Photovoltaics Finer features than current
method, non-contact
PSAs and Glues Variable imaging, precision
deposition
The use of inkjet as a mainstream, single-
pass production process is emerging as a
viable alternative to other process methods.
Its selected use in appropriate applications
has resulted in significant technical and
commercial successes.
With continued adoption and further
system progress, it is expected inkjet will
be a dominant manufacturing process that
plant engineers will consider for a host of
production applications.
Dr.RichardBakeristheDirectorOfBusinessDevelopmentforDimatixTechnologyIntegrationGroup,
(
DTI).DTIdesigns,
manufacturesandintegratescustomprintingsystemsforindustrialenduserapplications,
incorporatingDimatixPiezoInkJetTechnologyintoindustrialprinting,
decoratinganddepositingapplications.
RichhasbeenwithDimatixformorethan11years.
EdwardChrusciel,
MarketingDirectorinSpectra’sprintingdivisionatFujifilm,
handlesmarketing,
corporatecommunicationsanddevelopmentofnewbusinessopportunities.
Hehasexpertiseinhigh-
resolutionlaserrecorders,
colorscanning,
digitalworkflow,
satellitetransmissionandinkjetprinterandcomponentdevelopment.
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First Quarter 008 Visit SGIA at SGIA.org