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Rapid
Prototyping Choices for the Inventor
By Matthew Yubas
Before
advances in computers and materials, a complex prototype could take
weeks or months to build. Today, the most technically advanced method
to create a prototype is known as Rapid Prototyping (RP). With an RP
machine, a prototype can be produced in a matter of hours.
RP was invented in 1988 with the introduction of Stereolithography by
3D Systems of Valencia, California. Rapid Prototyping machines literally
create an object out of liquid resin, powder, or sheets of laminated paper.
Costs for this process depend on the size and complexity of the object.
A small prototype can start at $250. Costs increase for size, complexity,
and painting or silk screening.
In general, RP is useful for showing a model to a focus group or trade
representative. It also provides engineering proof of concept. The following
are the leading methods used in Rapid Prototyping:
- Stereolithography
Apparatus (SLA) – A process based on the use of photopolymer
liquid resins that solidify when exposed to ultraviolet light. A software
program transfers the designer's 3D CAD model into an electronic file
for stereolithography machines ("STL" format), composing the
information into thin cross-sections or layers. A laser beam then traces
each layer onto the surface of a vat of photopolymer resin, building
the part in repeated layers until a solid replica of the original CAD
model is completed. SLA is one of the least expensive prototype methods
and can be produced quickly.
- Selective
Laser Sintering (SLS) – A process that creates solid three-dimensional
objects, layer by layer, from plastic, metal, or ceramic powders that
are "sintered" or fused using carbon-dioxide laser energy. The inherent
material versatility of SLS technology allows for a broader range of
advanced rapid prototyping and manufacturing applications. SLS costs
more than SLA, but is stronger, more durable, is heat resistant, and
chemical resistant.
- Fused
Deposition Modeling (FDM) – A process that creates successive
cross-sections of a three-dimensional object from threads of plastic
or casting wax. Similar to a hot glue gun, plastic is extruded through
the modeler tip of the FDM machine. The FDM modeler head moves along
both the x- and y-axis across a foundation and deposits a layer of material.
This process continues until all layers of the part have been completed.
FDM is not as popular as SLA or SLS.
- Laminated
Object Manufacturing (LOM) – A process that creates a three-dimensional
object from layers of paper with a polyethylene coating on the backside.
A sheet of paper is fed through the machine with the aid of small rollers.
As the paper is fed through, steam is used to heat the paper’s
coating so that each new layer will adhere to the previous one. A carbon-dioxide
laser then traces, or etches, the outline of the cross-sectional pattern
into the top layer of paper. Once the laser has finished etching the
pattern, it burns a border into the paper that contains the etched pattern.
This enables the part to stay intact as each new layer is created. Since
LOM parts are made from paper, humidity and temperature affect the structure.
Therefore, lacquer is often added as a protective measure. Overall,
LOM is very useful for creating large parts quickly.
- 3D
Printing – A process that creates a three-dimensional object
using powder material. A type of ink-jet printing head selectively deposits
or "prints" a binder fluid to fuse powder in designated areas. The platform
is lowered, more powder added and leveled, and the process repeated.
(Typical layer thickness is on the order of 0.1 mm.) This process is
very fast, and produces parts with a slightly grainy surface. The finished
part can be filled and coated with special types of resin, urethane,
glue, or wax to improve its strength and durability.
Conclusion
Prototypes can be made by hand or with simple machines. But for a physical
part that is complex to make, rapid prototyping methods may be your solution.
Search for a prototype company using the Internet or Yellow Pages under
the heading of Prototype or Product Developing.
See also: Free Guide to the Invention Process | Invention Success Kit
About
the Author
Matthew Yubas is a Certified Professional Marketing Consultant for the
Small Business Development and International Trade Center. He has developed
products for 20 years as an engineer, product manager, and independent
consultant for startups, small business, and Fortune 500 companies. He
has launched new products such as software applications, wireless devices,
and websites. In addition, he has helped clients in a diverse number of
industries that include photography equipment, auto accessories, soy candles,
children's clothing, sporting goods, digital art, and home décor.
He has earned a B.S. in Engineering and an M.B.A. in Management. Information
about his new Invention Success Kit is available at www.ProductCoach.com.
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