Why rapid prototyping?

Most commercially available rapid
prototyping machines use one of these
techniques
• Stereo lithography (SL or SLA)
• Laminated object manufacturing
• Selective Laser Sintering
• Fused deposition modeling
• Solid Ground Curing
• 3D ink jet printer

The main technology in which photo polymerization is used to
produce a solid part from a liquid is SLA. This technology
employs a vat of liquid ultraviolet curable photopolymer resin and
an ultraviolet laser to build the object’s layers one at a time.

Laminated object manufacturing
An LOM apparatus uses a continuous sheet of material — plastic, paper or
(less commonly) metal — which is drawn across a build platform by a
system of feed rollers. Plastic and paper build materials are often coated
with an adhesive. To form an object, a heated roller is passed over the sheet
of material on the build platform, melting its adhesive and pressing it onto
the platform. A computer-controlled laser or blade then cuts the material
into the desired pattern.

Selective laser sintering
This technology uses a high power laser to fuse small particles
of plastic, metal, ceramic or glass powders into a mass that has
the desired three dimensional shape

Solid ground curing

This process is unique in that entire slices of a part are
manufactured at one time. As a result, a large
throughput is achieved, compared with that from other
rapid-prototyping processes. However, solid-ground
curing (SGC) is among the most ex-pensive processes;
hence, its adoption has been much less common than
that of other types of rapid prototyping.

3D Printing
The 3D printing technologies can be divided in the following:
inkjet printing
fused deposition modeling
polymer jetting (poly jet) or multi-jet.
First of all, it will describe briefly the most used 3D printing
technologies.

Fused deposition modeling

Fused Deposition Modeling (FDM) is an additive
manufacturing technology commonly used for modeling,
Prototyping, and production applications. The FDM
technology works using a plastic filament or metal wire which
is unwound from a coil and supplies material to an extrusion
nozzle which can turn the flow on and off. The nozzle is heated
to melt the material and can be moved in both horizontal and
vertical directions by a numerically controlled mechanism,
directly controlled by a computer-aided manufacturing (CAM)
software package. FDM Technology was invented about two
decade ago and has continued to lead RP revolution ever
since. Even today FDM is most widely used RP technique.
Aerospace industries are employing FDM technology
Aerospace icons like NASA & Piper Aircraft employ the
most exciting FDM (3D printing) applications Rover has
FDM Parts “You always want it to be a light as possible, but
you also want it to be strong enough.” — Chris Chapman,
NASA test engineer in the world

• To increase effective communication.
• To decrease development time.
• To decrease costly mistakes.
• To minimize sustaining engineering changes.
• To extend product lifetime by adding necessary
features and eliminating redundant features.
• Increasing number of variants of products.
• Increasing product complexity.
• Decreasing product lifetime before obsolescence.
• Decreasing delivery time.

Disadvantages
Some sources are of the opinion that rapid prototyping
is not effective because, in actual, it fails in replication of
the real product or system. It could so happen that some
important developmental steps could be omitted to get a
quick and cheap working model. This can be one of the
greatest disadvantages of rapid prototyping. Another
disadvantage of rapid prototyping is one in which many
problems are overlooked resulting in endless
rectifications and revisions. One more disadvantage of
rapid prototyping is that it may not be suitable for large
sized applications.

Future
Metal prototypes cannot be made with high
degree of accuracy if further developments are
made in this aspect prototype and products can
be manufactured at a time. It is predicted by
some additive manufacturing advocates that this
technological development will change the nature
of commerce, because end users will be able to do
much of their own manufacturing rather than
engaging in trade to buy products from other
people and corporations.

References:
1. Lisa Armano: "Rapid Prototyping Technologies and Build Time Models",
A Thesis Presented to the Graduate and Research Committee of Lehigh University in
Candidacy for the Degree of Master of Science
2. R.Udroiu, N.V.Ivan: RAPID PROTOTYPING AND RAPID MANUFACTURING
APPLICATIONS AT TRANSILVANIA UNIVERSITY OF BRAŞOV, Bulletin of the Transilvania
University of Brasov • Vol. 3 (52) – 2010.
3. Prof. Deepa yagnik: Fused Deposition Modeling – A Rapid Prototyping technique for
Product Cycle Time Reduction cost effectively in Aerospace APPLICATIONS IOSR Journal of
Mechanical and Civil Engineering (IOSR-JMC)
4. Mr. D. CHANDRAMOHAN, Dr. K. MARIMUTHU: RAPID PROTOTYPING/RAPID TOOLING
– A OVER VIEW AND ITS APPLICATIONS IN ORTHOPAEDICS, RAPID PROTOTYPING/RAPID
TOOLING – A OVER VIEW AND ITS APPLICATIONS IN ORTHOPAEDICS.
5. A Report on the future of rapid prototyping
6. www.3dprinting.net