This paper was presented in December 2000 at EuroMold in an
event titled "RP - Rapid Production: An International
Conference."
Using
RP Methods for Production Parts
Terry
Wohlers
Wohlers Associates, Inc.
Abstract
Industry
consultant Terry Wohlers discusses a number of industries and applications
that are ripe and ready to use RP for the production of final manufactured
parts. Among them are parts for business jets, helicopters, racecars,
high-end consumer and industrial automobiles, antique cars, sports gear,
hearing aids, surgical implants, and prosthetics. Wohlers will also
provide an update on some of the companies that have pioneered the idea of
"rapid production" including Specific Surface, Therics, and
Align Technology. In the future, RP will mean rapid production.
Biography
Industry
consultant Terry Wohlers is president of Wohlers Associates, Inc., a
consulting firm he founded in 1986. Wohlers' highly sought after views and
opinions come from years of collecting and analyzing market data, coupled
with his work as an advisor to major organizations in the U.S., Europe,
Asia, and South America. He has authored nearly 250 books, articles,
reports, and technical papers on engineering and manufacturing automation.
In 1992, Wohlers led a group of 14 individuals from industry and academia
to form the first association dedicated to rapid prototyping. In 1998, he
co-founded the Global Alliance of RP Associations (GARPA) involving 14
member nations around the world. Wohlers is serving as the chairman of
this conference.
Rapid
production
is the use of methods of rapid prototyping (RP) to manufacture final
end-use parts. Manufacturing companies are beginning to explore this idea
as they seek methods and strategies of producing finished products more
quickly than has been possible in the past. Delays in tooling translate
into lost market share when a company's competitors move swiftly, so rapid
production can help reduce, or in some cases, eliminate these delays.
Indeed, when only hundreds or a few thousands parts are needed, methods of
rapid production may prove to be a viable replacement to injection
molding. The use of RP patterns for the production of metal castings for
finished products is another important strategy that companies are now
considering.
Several
factors will determine whether it makes sense to consider methods of RP
for manufacturing. Companies that make parts that are relatively small and
in relatively low quantities will be the first to embrace it. Also, when
the cost to produce parts is high, it may be less expensive to use methods
of RP to manufacture the parts. Parts that do not require a high quality
surface finish and are hidden from view are also good candidates. In cases
where tens or hundreds of thousands of parts are required, it may be
feasible to produce and deliver finished parts using methods of rapid
production in parallel with the creation of tooling. This approach would
permit the company to sell and gain valuable feedback on the product while
waiting for the tooling and injection molded parts.
Aerospace
The
cost of individual parts for the aerospace industry is high. Consequently,
this is an industry that could benefit from rapid production. However, the
demands of this industry are quite high. Rigorous testing and
certification is necessary before one can use materials and processes for
the manufacture of aircraft parts. Even so, Boeing's Rocketdyne has
successfully used RP technology to manufacture hundreds of parts for the
International Space Station and the entire space shuttle fleet.
Using
DTM's Sinterstation, Rocketdyne has produced parts in glass-filled nylon,
as well as a super alloy that was developed in-house. The company is also
manufacturing parts for military applications, such as the F-18 fighter
jet.
Laser sintered glass-filled nylon part
used in the International Space Station,
courtesy of Boeing Rocketdyne.
The
manufacture of business jets is another market that could benefit from RP
for the production of finished parts. Individual part cost is high and
quantities are low. Potential parts include custom interior plastic pieces
and metal parts that would otherwise be manufactured using investment
casting. Helicopters, for both recreation and industrial use, would
benefit similarly.
Automotive
The
racecar industry is already benefiting from RP technology for the
production of metal castings. C.R.P. Technology, a division of the
Cevolini Group of Italy, is using laser sintered CastForm PS from DTM to
produce patterns for titanium castings. Parts include uprights, suspension
supports, clutch boxes, steering boxes, and gear boxes. The Minardi Team
of Italy is using these parts directly on its Formula 1 racecars. While
this is not a direct manufacturing process like Rocketdyne's application,
it is none-the-less an application of rapid production using RP.
Replacement
parts for antique cars will also benefit from rapid production. For
hard-to-find parts, owners will turn to RP to custom manufacture plastic
and metal parts. As the technology improves, companies that produce
high-end cars and trucks will take advantage of RP to produce custom parts
specified by the buyer, giving automobiles a touch of personality that has
not been affordable in the past.
Medical
Applications
Several
interesting medical applications are in the early stages of development.
In the field of orthodontics, Align Technology is pioneering a new way of
straightening teeth using stereolithography technology from 3D Systems.
Using Align's proprietary Invisalign process, patients no longer wear
conventional metal braces. Instead, they wear custom-fit clear plastic
aligners that straighten the teeth. The company is in the process of
purchasing and installing 10 SLA 7000 machines. The list price of the SLA
7000 is about $800,000, so this is a serious investment on the part of the
company. The SLAs are used to produce patterns that are in turn used to
manufacture each custom aligner. The patient receives 12 to 48 aligners,
depending on the particular case. The individual wears each aligner for
about two weeks, removing them only to eat, brush, and floss. As they
replace each aligner with the next, the teeth moves little by little.
Invisalign was launched in July 1999, and already, more than 6,000
patients are in treatment.
Plastic aligner created using
the Invisalign process,
courtesy of Align Technology
The
production of hearing aids is another interesting area that is being
explored. As early as 1989, one major manufacturer of custom-fit hearing
aids investigated the idea extensively. Since then, RP machines,
materials, computers, and laser scanners have improved dramatically,
making the idea much more feasible today. A number of hearing aid
manufacturers are currently evaluating RP and related technologies for the
manufacture of custom-fit shells that fit in the ear canal. A non-contact
scanner digitizes a silicone impression of the ear and custom software
prepares the data for fabrication on the RP machine.
Left: Believed
to be the first fully functional hearing aid
produced from a stereolithography shell.
Right: Hearing
aid
Deposition Modeling (FDM).
Therics
has produced a machine called TheriForm for medical applications. It is
based on the Three-Dimensional Printing (3DP) technology invented at the
Massachusetts Institute of Technology (MIT). TheriForm is used to
manufacture time-release "designer pills" by printing binders
and medicine onto the surface of a powder. The process builds up one voxel
at a time, creating microdose tablets that can release one or more drugs
in a series of controlled stages. The Series 3200 TheriForm machine, which
uses a print head consisting of either 16 or 32 nozzles, is capable of
printing up to 60,000 oral dosage forms per hour.
Therics
also uses the technology to produce resorbable tissue scaffolding and
implants for cartilage, tendon, and bone substitutes. They are built from
powdered natural or synthetic bones, with the latter being either
bioceramic or bioglass, and could include drugs, growth factors, and gene
fragments to promote cell regeneration. The process has been FDA validated
in the USA, although the products themselves are still under development.
Consumer
Products
In
the future, companies will manufacture customer products, such as
footwear, using non-contact scanners and methods of RP. Over the past few
years, this idea has been discussed and evaluated repeatedly and some have
even tried to make a business of it. Companies that manufacture expensive
shoes, such as those worn by professional athletes, will be the first to
use RP for rapid production.
One
can also envision the use of RP to produce custom-fit eyeglasses and
safety goggles. The cost of purchasing and operating RP machines will need
to drop significantly before this approach makes economic sense, although
it is likely to happen.
Makers
of scuba and snorkeling gear will also benefit from rapid production. Dive
masks must fit perfectly, yet it is not easy to obtain a good fit. The
result is a mask that fills with water—something that divers prefer to
prevent happening when diving deep below the surface. Dive fins also fit
poorly because they come in standard sizes. Even a size that is supposed
to fit well often does not. For this reason, divers would pay a premium to
get fins that fit comfortably.
Other
Applications and Industries
In
the USA alone, organizations spend an unbelievable amount of money on
professional and college sports. Yet American football players, for
example, are at great risk due to the brutalities of the sport. At any
time on the field, the season can come to sudden end for a top athlete.
Consequently, teams take every precaution necessary to reduce the risk of
injury. Helmets and shoulder pads come in standard sizes, but they don't
always fit as well as they should. Using non-contact scanners, software,
and RP machines, it is possible to manufacture helmets and pads that are
custom-tailored to the specific needs of the athlete.
Museums
are looking for less expensive ways of reproducing bones and valuable
artifacts. With technology that is available today, it is possible to
reproduce replicas in an efficient and affordable way. A few museums have
discovered the benefits of RP, but many more will use it in the future for
the rapid production of items that would be impossible to replace if lost
or destroyed.
Specific
Surface is another company that has licensed MIT's 3DP technology. The
company has developed a process, called CeraPrint, for rapidly producing
high performance ceramic filters for industrial and diesel exhaust
applications. Using CeraPrint, the company claims that it can efficiently
produce filters and substrates in quantities of 10 to 100,000. Over
the past year, Specific Surface has been working on the development of
recrystalized silicon carbide filters for particulate removal from diesel
engines. The company also produces filters for liquids. For example,
Kikkoman in Japan has been using its CandleStac products for the
filtration of soy sauce. The modules clarify high viscosity soy sauce
(10,000 cps) removing particles 15-20 microns in diameter at 1000 ppm.
Ceramic
filter produced using the CeraPrint process,
courtesy of Specific Surface
Companies
that produce electrical connectors are exploring ways in which they might
use RP technology to manufacture products. The fine resolution offered by
some stereolithography processes in the USA and Japan makes it possible to
manufacture connectors and other electrical components in configurations
that would be impossible to produce any other way.
Conclusions
The
idea of rapid production conjures up questions and issues such as
"how would designs change if one could manufacture parts without the
constraints imposed by tooling?"
Using this approach, one could design and manufacture parts without
regard to draft, die lock conditions, or even assembly. Historically,
these problems have created a need to reduce the complexity of part
geometry and have stifled the imagination and creativity of designers.
This, in turn, has made it difficult to manufacture some products that may
have broad market appeal. In the future, companies will pay a premium for
the flexibility of machines that can produce quantities of production
parts quickly and economically, without the need for tooling.
Part
of the challenge for companies to move toward the idea of rapid production
is the long-established traditions and cultures within organizations. Some
companies may appear to be well suited for this new approach to
manufacturing, but the "thinking" within the organization may
prevent it from happening. The best candidates are companies with
progressive thinkers and individuals willing to take risks, push the
limits, and try new ideas and technology.
Copyright 2000 by Terry T. Wohlers
