Editor's Note: There have been
dizzying changes in the field of rapid prototyping since the first systems were
introduced in the 1980s. For starters, the field is now known as "additive
manufacturing," referring to the process of making three-dimensional models
layer by layer. These systems were originally intended for making prototypes
quickly from a CAD file. Now, there are high-capability machines that make
precision parts using the same technology. This paper submitted by Stratasys, a
major manufacturer of both types of machines, provides guidelines for picking
the right unit for your needs.
When
planning to purchase an additive manufacturing system, buyers will find
capabilities and a price range wider than products from most any industry.
Systems can range from several hundred dollars for a hobbyist unit to nearly $1
million for some high-performance systems. It's no wonder there is confusion
with respect to the product segments.
This paper
addresses the capabilities, roles and positioning of systems geared for
professional use. Beginning with the most basic information - the definition of
3-D printers - there are two product classes. While clarifying the "typical"
roles and strengths of each, it also shows that there is overlap between the 3-D
printers and their big brothers, sometimes referred to as 3-D production
systems.
As additive
manufacturing system prices have decreased, interest has swelled in owning a
system to produce rapid prototypes, patterns, tooling and manufactured goods.
Further fueling that interest is an increase in the number of technologies,
systems and options available. Choice is the operative word, and those choices
include entry-level systems priced below $15,000, as well as machines selling
for more than $900,000.
With so many
options, how do organizations know which is the best choice? How do they know
what is a reasonable investment for an additive manufacturing system that will
do their job right? To answer these questions, they begin with an understanding
of the differences between 3-D printers and 3-D production systems. Knowing the
distinctions between the two classes of systems allows informed decision-making
that balances needs, wants and budget.
There are 10
general factors that distinguish 3-D printers from 3-D production systems. For
some, the first factor, price, may be the only consideration. But for those
with some flexibility in their capital equipment budgets, the other nine
factors will guide the selection process. But this does not necessarily mean
that more money will be spent. Many companies are pleasantly surprised to find
that they can do all that they want with a low-price 3-D printer. Many others
happily invest more in a 3-D production system that offers higher performance.
And countless others invest in both - running 3-D printers and 3-D production
systems side-by-side.
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What are 3-D Printers and 3-D
Production Systems? Additive
manufacturing systems were once called rapid prototyping machines and simply
labeled as "low-end" or "high-end," and distinguished by price. When opting for
a "low-end" machine, there was a big price to pay in quality or performance.
As the
market and technologies matured, a new term, "3-D printers," sprang up. But
instead of replacing "low-end" as a class descriptor, it became an over-used
catch phrase that muddied the waters. To this day, there isn't universal
agreement on the definition of 3-D printers. For some, the term covers all
additive manufacturing technologies. However, the majority defines 3-D printers
as compact, low price and easy to use. With this understanding, a 3-D printer
is analogous to a desktop paper printer that is dedicated to one person or
shared among a small team of co-workers.
Conversely,
a 3-D production system is similar to a centralized copy center machine with
higher output, more controls and which serves a whole office's needs. They are
the "high-end" systems in 1990s lingo. In general, they offer more capability
and higher performance with a larger price tag. Yet, the distinctions between
the two classes are not that clear cut. To appreciate the subtle differences,
consider the 10 distinguishing characteristics.
Keep in mind
that these characteristics are general and typical, but there are exceptions.
10 Distinguishing
Characteristics
1. Price:
- 3-D
printers: $10,000 to $50,000
-
3-D
production systems: $50,000 and above
The base
price of machines is the simplest and most obvious differentiator between the
two classes. In the additive manufacturing market, low price does not translate
to low value. Value is determined by considering all the characteristics to
find the system that can do the job while bringing the best return on
investment.
2. Capacity
/ Build Envelope:
-
3-D
printer: normally less than 8 x 8 x 8 inch
-
3-D
production system: normally greater than 1 x 1 x 1 ft
The size of
a machine's build envelope determines its capacity, typically both in terms of
part size and total throughput. 3-D printers, which are designed more for
office use or desktop operation, have smaller build envelopes suited for small-
to mid-sized parts. These devices typically have build capacities that do not
exceed 12 inches in any dimension. 3-D production systems, on the other hand,
have the capacity to build parts that are measured in feet. In this class, two
to three feet is a common measurement for the length, width or height of the
build envelope.
Capacity is
an important consideration because it is best to avoid building parts in pieces
that have to be bonded together. Sectioning parts to fit in a build chamber
adds time, labor and cost while decreasing quality. Also, running an additive
manufacturing system multiple times to make one part decreases efficiency and
machine availability.
To increase operational efficiency and
total throughput, consider systems with the capacity to build many parts in a
single run. As more
parts are consolidated in each run, operational costs decrease while
efficiencies rise. A bonus is that a lot of parts can be packed into a single
run that is launched Friday night and left to run unattended over the weekend.
3.
Materials:
- 3-D
production systems: eight or more
Material
properties play a role in every process selection. Whether the application is
for a "down-and-dirty" concept model or a high-caliber production part, there
will be some degree of consideration given to the materials that are available.
In every case, the application needs a material that will perform well.
3-D printers
typically do not offer broad material selections. Most give users a choice of
just one or two general-purpose materials. In this class, the systems offer
adequate, rather than exceptional, mechanical and thermal properties. In stark
contrast, a strength of 3-D production systems is the number of materials
offered and the breadth of properties available. 3-D production system users
can specify a material that matches the specific needs of an application by
selecting from a range of options that include specialized, highly engineered
thermoplastics such as ULTEM
® 9085.
In general,
the material offerings of 3-D production systems make them better suited for
functional testing, field testing, product trials, and creating manufacturing
tools or finished goods. Each part in an assembly can be produced from a
different material that is selected for the right combination of advanced
material properties.
4. Speed:
- 3-D
printers: Not applicable
- 3-D
production systems: Not applicable
The speed of
the additive manufacturing process is an important consideration, but it is not
one that clearly distinguishes 3-D printers from 3-D production systems. In
this area, bigger investments do not guarantee shorter build times. For
example, there are 3-D printers that for one-tenth the price can build parts 10
times faster than some 3-D production systems. On the other hand, there are 3-D
printers that take days to build what can be completed in hours with certain 3-D
production systems.
For a
manufacturer that offers both 3-D printers and 3-D production systems that do
not share a common technology - there is no correlation between the speed of
the process and the price tag. However, for a manufacturer with a technology
that spans both classes, there is a direct link between speed and price.
If speed is
measured in terms of throughput, 3-D production systems will again outpace 3-D
printers. Combining build speed with capacity, the larger systems will, in
general, deliver higher production rates on a weekly or monthly basis. This is
an important point when faced with high-volume prototyping demands, and it is a
critical factor when considering the technology to manufacture end products.
Note: Always evaluate the total process time for a
technology. Build times alone are deceiving. So, include all time and labor
needed on the front end to prepare a machine and on the back end to remove and
finish the parts.
5.
Ease-of-Use:
- 3-D
printers: Occasional User
- 3-D
production systems: Trained Operator
If a 3-D
printer isn't easy to learn and easy to use, it should not be called a 3-D
printer. Ease-of-use is imperative for these devices since they are intended to
be used as a CAD-output tool. Occasional users are not skilled machine
operators and cannot afford to spend days in training or hours preparing and
operating a machine. From start to finish, the process must be simple,
straightforward and effortless.
A vision
shared by most 3-D printer manufacturers is to make their machines as
transparent and unnoticed as the process of printing a document. Admittedly,
these systems are not quite to this level, but some are close. From CAD output
to finished parts, some are almost as labor-less as the process of printing a
few dozen two-sided pages on a standard paper printer. In other words, it's not
quite as simple as click-and- print, but it requires only a few extra steps and
minimal thought.
To gain
higher performance and greater functionality, 3-D production systems generally
sacrifice ease-of-use. The advances in processes, materials and controls place
additional demands on the user. To get the most out of 3-D production systems,
there will be operators who are responsible for the oversight, maintenance and
operation of the machines. These technicians will have undergone advanced
training on the system and will continue to learn the subtle nuances of
operations with each part that it produces. The technicians will also learn the
unique processing requirements for each of the materials they use.
There is an
exception, however. For the scalable technologies, like FDM, that are used in
both 3-D printers and 3-D production systems, ease-of-use is possible in both
classes. For everyday parts, the 3-D production system can be run as easily as
a 3-D printer. However, when advanced capabilities are needed, someone other
than a casual user may be called upon to leverage all that the system offers.
6. Operator
Control:
- 3-D
production systems: Substantial
In return
for ease-of-use, 3-D printers remove most of the operator control and user
options. Instead of a computer screen filled with user-defined variables and
selections, the casual user is presented with a limited number of
pre-programmed routines and only a few options. And the choices must be applied
globally to a part or across the entire job. In this way, 3-D printers are
analogous to point-and-shoot cameras.
3-D
production systems, on the other hand, are more like the sophisticated digital
SLR cameras that have swappable lenses, variable flash settings, F-stop
adjustments and ISO settings. 3-D production systems, like their camera
counterparts, give operators control of a multitude of variables to fine-tune
part quality, adjust part characteristics and influence production rates.
Unlike their 3-D printer counterparts, the most advanced systems in this class
allow the user to apply many control parameters at the feature level of the
part. For example, to save time and material, the machine can make an
ornamental feature hollow and a functional feature solid. This level of
control, combined with material selection, is why 3-D production systems are
the likely candidates for advanced applications in prototype development and
manufacturing.
7. Accuracy:
- 3-D
printers: Acceptable to Good
- 3-D
production systems: Good to Excellent
"Geometry
dependent" is the qualifier on any statement of dimensional accuracy and
repeatability for additive manufacturing systems in both technology classes.
Yet, it is safe to assume that in the case of accuracy and repeatability,
buyers will get their money's worth. Overall, 3-D production systems are more
accurate and offer greater repeatability than their lower price 3-D printer
siblings.
This is not
to say that 3-D printers cannot make parts with reasonable dimensional
accuracy. They can. There is just less emphasis on this attribute and less user
influence over it. 3-D printers are designed to be simple, cost-effective
machines targeted for early models and prototypes where looser tolerances are
acceptable. With this target in mind, 3-D printer manufacturers place less
priority on accuracy. And as noted previously, the simplified user interface
removes the option of fine-tuning to dial in parts for better quality.
With higher
expectations of part quality, the manufacturers of 3-D production systems are
investing in high-grade components, tight process controls and precise
calibration. No longer just for prototyping, the best 3-D production systems
are designed and manufactured as if they were any other machine on the
manufacturing floor. Tight and repeatable tolerance is a reasonable expectation
when investing in this class of additive manufacturing technology.
Although the
quality differences may be difficult to see with the naked eye, they will show
up when parts are scrutinized by quality control. It will also become apparent
when seeking confirmation of a machine's accuracy capabilities. For 3-D
printers, there are general tolerance claims but no exhaustive studies that
qualify accuracy and repeatability. For 3-D production systems, it is
reasonable to expect a study that is thorough, rigorous and statistically
sound. Without this level of data, buyers would find it difficult to trust that
a 3-D production system could actually be used for production.
8.
Facilities:
- 3-D
printers: Office-like Environment
- 3-D
production systems: Lab or Shop Environment
The allure
of 3-D printing has been the vision of producing models and prototypes where
the design and engineering work is being done. To make this vision a reality, the
3-D printing process must be clean, quiet, cool and odorless. Requiring no more
than a wall outlet and network connection, the 3-D printing process becomes an
in-office output device. Major advances toward this goal have been made in
recent years.
Although the
vision for 3-D printers is not quite a reality, there are several units on the
market that fit nicely in an office environment. But even the most
office-friendly 3-D printer will likely have a separate workspace in a nearby
room for part finishing. Access to a water supply and drain; well-lit and roomy
work surfaces; and supply storage areas are conveniences that are likely to be
located outside of the engineering offices.
3-D
production systems, for the most part, are located in workshops and labs or
placed on the manufacturing floor. These machines are big and bulky, not
something that most want in their offices. They often have shop-oriented
requirements for power, compressed gas, temperature control, humidity control,
vibration dampening or debris containment. For most 3-D production systems, the
projects often dictate that the parts go through secondary operations that may
employ a variety of shop tools and supplies. This work must be kept in the
shop. The added facility requirements for 3-D production systems will have an
effect on the initial system investment and ongoing operating expenses.
9.
Centralized Operations:
- 3-D
printers: Distributed
- 3-D
production systems: Centralized
Additive
manufacturing offers two modes of operation: centralized and distributed.
Companies may choose to distribute machines throughout the organization or
centralize them in one area that is managed by a dedicated staff. Some want the
flexibility and independence that a distributed network of systems offers.
Others prefer the control, oversight and efficiencies of a centralized grouping
of systems.
The
distributed network is the domain of 3-D printers. In this operating mode,
designers and engineers have direct access to their prototyping tools. Instead
of sending jobs off to be scheduled and built, the engineering team gains the
independence and control that comes from deciding its own priorities and making
its own parts.
In a
centralized operation, the shop staff receives all part requests, schedules
production, manages runs, and oversees post processing. This department takes
on the work of making models and parts for the whole organization. With
responsibilities to maximize efficiencies, minimize cost, and maximize
responsiveness, the build schedule has priorities beyond the urgent need for a
single part. So, a rush job may be bumped to a later time because there are
other rush jobs already in queue.
10.
Overhead:
- 3-D
production systems: Moderate to High
Distributed,
self-serve operations do not place additional overhead burdens on an
organization. The staffing remains the same since those who need the parts are
those who build and finish them.
Centralized
operations require someone to manage day-to-day operations, including the
production schedule. When applying the 3-D production systems to advanced
applications, such as tooling and finished goods production, there will be
additional demands for skilled technicians that can leverage the controls that
these systems offer. Finally, depending on the complexity of the system, there
may be a need for someone to perform post processing, part finishing, and
secondary operations.
As the
application progresses from simple concept models to advanced manufacturing,
more is expected from the additive manufacturing systems and more is needed
from the team that tends to their operations.
Subtle Differences
With
additive manufacturing, organizations can get a lot of capability affordably.
Being less expensive does not mean that a 3-D printer is an inferior solution
to a 3-D production system. It is simply a different solution. Using the 10
differentiating factors, a solution may be found to best match the
organization's needs, budgets, and operating style.
Choosing
between 3-D printers and 3-D productions systems is not like picking a
two-wheel scooter or an 18-wheel big rig. It is more like picking from a
selection of compact cars, luxury sedans, SUVs and pickup trucks. The application
will drive the decision. And continuing with this analogy, ultimately companies
will find the need to have one for commuting and another for towing the
pleasure boat, which is to say that they may find themselves running both 3-D
printers and 3-D production systems.
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