How to Select a 3D Printer for your Plant

Once a novelty technology used by a few
cutting-edge companies to make part
prototypes, 3D printing, also known as
additive manufacturing, is now considered a mainstream
technology for the factory floor.

A good fit for automotive, aerospace, and
medical industries, 3D printing is also the perfect
fit for customized work. 3D printing’s early value
proposition has always been its ability to shorten
production development cycles, with designers and
engineers using 3D printing to produce quick-turn
prototypes. The technology and materials then
evolved to take 3D-printed prototypes and use
them in a functioning manner for testing. Now the
industry is moving 3D printing into a production
support role, leveraging the printers to make jigs,
fixtures, or end of arm tools customized for a particular
work process.

An example of a company working with this
latest stage of 3D printing technology is Ecco, a
family-owned footwear company that has been in
business since 1963. Ecco owns every step of its
traditionally manual shoemaking process. Typically,
the sole is molded and then assembled by hand and
glued to the upper part of the shoe. Applying the
Direct Injection Process (DIP) using a two-component
polyurethane mix, Ecco can now create a
one-piece 360 degree bond that secures the upper
part of the shoe to the midsole.

The catch here is that making molds for the DIP
process from CNC aluminum comes with long
lead times and is an expensive tooling process. It’s
not an efficient way to go when multiple designs
are being rolled out. So, Ecco turned to Stratasys’
Origin One, a 3D printer that enables flexible
production of end-use parts in a diverse range of
high-performance materials. Using its Programmable
Photopolymerization (P3) technology, an
evolution of digital light processing (DLP), the
printer achieves accuracy, consistency, detail, and
throughput.

In this example, the 3D printer is still playing
a supporting role, but that’s a stepping stone to
the ultimate goal of production-ready parts. “The
emerging area and holy grail of the industry is end
use part production for a certain app, skipping the
traditional tooling process all together and cutting
months out of the cycle time,” said Rich Garrity,
Stratasys’ president of the Americas.

In fact, Stratasys already has some early use
cases of companies doing this. “We can now
print more high performance or exotic materials
that can go on a commercial aircraft, for
example,” Garrity said. “Better materials and a
more repeatable process will have manufacturers
using [3D printing] for production.”

Two popular 3D-printing services at Proto Labs: SLA allows for more cosmetic features, while SLS brings a boost in durability.Two popular 3D-printing services at Proto Labs: SLA allows for
more cosmetic features, while SLS brings a boost in durability.
Printer selection

At this point, there is absolutely no question
that 3D printing is coming to the production
floor. Now, the question manufacturers need to
consider is: What kind of 3D printer to use?

A quick search on the Internet for “3D printers”
delivers an acronym alphabet soup: SLA, SLS,
FDM, MFJ, DMLS, and numerous others. It’s difficult to know what these technologies are, much
less if they are right for your application.

“Generally speaking, deciding which 3D printing
process to use comes down to material requirements,
such as strength, durability, and temperature
resistance, as well as design requirements,
including feature size, resolution, part size, etc.,”
said Rachel Hunt, 3D printer manager at ProtoLabs, which provides rapid manufacturing of low volume
3D-printed, CNC-machined, sheet metal,
and injection-molded custom parts for prototyping
and short-run production.

Garrity agrees. “In the 3D printing industry
there is no silver bullet. There is not one process
that solves all of the applications out there that
customers care about. The reality is, it [3D printing]
is being used at each stage of product development,
design, prototype, and production support.
So it depends on first determining what problem
you are trying to solve to guide yourself toward the
right technology.

Liz Stortstrom, an application engineer at HP
adds: “When we get into the space of additive,
we’re not talking about replacing all other processes,
we want to use it as a tool to complement
the processes you’re already using. Figure out how
to use it strategically to complement these other
methods so you’re getting the best results.”

Two popular 3D-printing services at Proto Labs: SLA allows for more cosmetic features, while SLS brings a boost in durability.Two popular 3D-printing services at Proto Labs: SLA allows for
more cosmetic features, while SLS brings a boost in durability.
Back to the basics

A good first step is to understand all of those acronyms.
Following is a list of popular 3D printing
technologies and a rudimentary explanation of
what they do, the materials used, and suggested
uses:

Stereolithography (SLA) is the first commercialized
3D printing technology, invented by Chuck
Hull, 3D Systems’ co-founder and chief technology
officer, in the 1980s. According to 3D Systems,
it uses an ultraviolet laser to precisely cure
photopolymer cross-sections, transforming them
from liquid to solid. Parts are built directly from
CAD data, layer-by-layer into prototypes, investment
casting patterns, tools, and end-use parts.
Once the SLA printing process is complete, SLA
parts are cleaned in a solvent solution to remove
any residual uncured resin from the part surface.
Cleaned parts are then cured in a UV oven.

  • Material—Photopolymers. SLA materials are
    available in a wide range of mechanical properties
    and can produce parts with characteristics similar
    to injection-molded ABS or polypropylene.
  • Suitable for applications such as snap-fit
    assemblies, automotive styling components,
    and patterns.

Selective Laser Sintering (SLS) is a powder-based
3D printing technology that uses a laser to fuse
material layers into a final part. The laser traces the
pattern of each cross-section of a 3D design onto
a bed of powder. After one layer is built, the build
platform lowers and another layer is built on top of
the previous layer. This process continues until every
layer is built and the part is complete.

  • Material—Thermoplastics. According to 3D
    Systems, SLS really shines when you need durable
    plastic parts. SLS uses production-grade
    nylon materials, resulting in durable, functional
    parts that last.
  • SLS is the technology of choice for a range
    of functional applications, such as jigs and
    fixtures, housings, snap fits, living hinges and
    other mechanical joints.

Direct Metal Laser Sintering (DMLS) builds high
quality complex metal parts from 3D CAD data.
In the machine, a high precision laser is directed to
metal powder particles to selectively build up thin
horizontal metal layers one after the other.

  • Material—Metals. DMP shapes any desired
    metal part geometry by melting metal powder
    layer by layer.
  • Often used in aerospace applications, it is a
    good technology for production of small, complex
    shapes.

Fused Deposition Modeling (FDM) technology
developed by Stratasys founder Scott Crump more
than 20 years ago, works with specialized 3D printers
and production-grade thermoplastics to build
strong, durable and dimensionally stable parts with
the highest accuracy and repeatability of any 3D
printing technology. The printer takes a spool of
plastic filament, melts it, and extrudes it on to a tray.

  • Materials—Industrial-grade thermoplastics, which
    makes the resulting parts extremely strong.
  • FDM 3D printed parts are in cars, airplanes,
    medical devices, and more.

Multi Jet Fusion (MJF) is a powder bed fusion 3D
printing technology developed by HP. it is similar
to SLS in that the printer lays down a layer of
material powder on the printing bed, then an inkjet
head drops fusing agents onto the print bed of
material. No binding, just controlling where in the
print bed absorbs more energy from the overhead
infrared lamps. The process continues layer by layer
until the build is complete.

  • Materials—Thermoplastics. MJF’s most common
    material option is Nylon PA 12, PA 11
    powders, but the breadth of available materials
    has expanded over the years.
  • MJF can achieve high strength parts and the
    overall process is efficient and fast, so this is
    good for higher volume applications.

Ultimately, the decision as to what technology to
use has to do with the process and the materials used.
And the materials you choose are based on mechanical
properties, strength, flexibility, the environment, and
any certifications it may need, such as flammability or
biocompatibility, noted HP’s Stortstrom.

“The process influences different factors like
strength and isotropy, meaning can you get the
same strength vertically that you can horizontally,”
Stortstrom explained during a presentation
at the Robotics Summit & Expo in May.
“That’s a big thing to look out for as you evaluate
different technologies.”

Stratasys Origin One 3D printer makes shoe molds for Ecco footwear company.Stratasys Origin One 3D printer makes shoe molds for Ecco footwear company.At your service

If the thought of purchasing a 3D printer still
seems confusing, you still have intermediary options. Companies like Stratasys and Proto Labs offer
3D printing services to help organizations with
rapid prototyping and production parts.

Stratasys offers seven additive technologies—
including its new selective absorption fusion
(SAF) technology for components with
complex geometries—in its manufacturing on demand
service. This gives smaller shops the advantage
of cutting-edge 3D printing technology
without the operating expense. Larger manufacturers
can use a hybrid approach and have some
printers onsite, but use the Stratasys Direct
service for overflow needs.

“We run banks of our printers and they just
send us a CAD file and we produce it for them,”
Garrity said.

Similarly, Proto Labs’ online 3D printing service
consists of six 3D printing technologies and a broad
material selection. The company offers several postprocessing
options to improve cosmetics or enhance
mechanical properties. With 120 printers, Proto
Labs can take a 3D file and turn it into plastic, metal,
and elastomeric parts in a matter of days.

Regardless of the approach, one thing is certain:
3D printing is a key technology to modern manufacturing.

“3D Printing will continue to be the ‘Swiss army
knife’-like tool that is used when the need arises
and it’s exciting,” said Proto Labs’ Hunt. “Fortunately,
it is here to help solve many manufacturing
challenges from concept to functional prototype to
end use part to end of life replacement part. It’s
especially going to be a manufacturing tool up-and-coming engineers will know they can leverage.
The R&D around materials and printers continues
to expand the options on the table.”

Indeed, Garrity feels the next step for 3D printing
is to set up an infrastructure that allows adoption
at a much bigger scale, meaning the ecosystem
of technologies, materials, and software connect to
other systems on the shop floor. “We’ll see cells of
3D printers working with automation and robots
taking parts oŽ the machine to move it to the next
post process for much greater throughput,” he said.