Rapid
Prototyping
&
In many fields, there is great uncertainty as to
whether a new design will actually do what is
desired. New designs often have unexpected
problems. A prototype is often used as part of
the product design process to allow engineers
and designers the ability to explore design
alternatives, test theories and confirm
performance prior to starting production of a
new product. Engineers use their experience
to tailor the prototype according to the
specific unknowns still present in the intended
design.
Rapid Prototyping
technology employ
various engineering e.g. computer control and
software techniques including laser, optical
scanning, photosensitive polymers, material
extrusion and deposition, powder metallurgy
etc. to directly produce a physical model layer
by layer (Layer Manufacturing) in accordance
with the geometrical data delivered from a 3D
CAD model.
Differences
between
conventional
Prototyping can improve the quality of requirements and
specifications provided to developers.
Reduced time and costs:
Users are actively involved in the development.
Quicker user feedback is available leading to better
solutions.
Errors can be detected much earlier.
Missing functionality can be identified easily.
High precision RP machines are still expensive.
RP systems are difficult to build parts with accuracy
under +/- 0.02mm and wall thickness under 0.5mm.
The physical properties of the RP parts are normally
inferior to those samples that made in proper materials
and by the traditional tooling.
The RP parts are not comparable to (CNC) prototype
parts in the surface finishing, strength, elasticity,
reflective index and other material physical properties.
All RP techniques employ the basic five-steps
processes:
1. Create a CAD model of the design.
2. Convert the CAD model to STL format.
3. Slice the STL file into thin cross-sectional layers.
4. Construct the model one layer atop another.
5. Clean and finish the model.
Workflow
of
RP
CAD model Pre process RP process Post process
Workflow
of
RP
First, the object to be built is modeled using a
Computer-Aided Design (CAD) software package.
Solid modelers, such as Pro/ENGINEER, tend to
represent 3-D objects more accurately than
wire-frame modelers such as AutoCAD, and will
therefore yield better results.
This process is identical for all of the RP build
techniques.
To establish consistency, the STL format has been
adopted as the standard of the rapid prototyping
industry.
The second step, therefore, is to convert the CAD
file into STL format. This format represents a
three-dimensional surface as an assembly of planar
triangles
STL files use planar elements, they cannot
represent curved surfaces exactly. Increasing the
number of triangles improves the approximation
Example of STL
model
This figure shows a
typical example of STL
model which is
composed of triangles
and each triangle is
described by a unit
normal vector direction
and three points
In the third step, a pre-processing program
prepares the STL file to be built.
The pre-processing software slices the STL model
into a number of layers from 0.01 mm to 0.7 mm thick, depending on the build technique.
The program may also generate an auxiliary
structure to support the model during the build. Supports are useful for delicate features such as overhangs, internal cavities, and thin-walled sections.
Desired part or model geometry
The fourth step is the actual construction of
the part.
RP machines build one layer at a time from
polymers, paper, or powdered metal.
Most machines are fairly autonomous, needing
little human intervention.
The final step is post-processing. This involves
removing the prototype from the machine and
detaching any supports.
Some photosensitive materials need to be fully
cured before use
Prototypes may also require minor cleaning and
surface treatment.
Sanding, sealing, and/or painting the model will
improve its appearance and durability.
Types
of
Rapid
Prototyping
Technologies
SLA --- Stereolithography
SLS --- Selective Laser Sintering
LOM --- Laminated Object Manufacturing
FDM --- Fused Deposition Modeling
Patented in 1986
, Stereolithography started
the rapid prototyping revolution. The
technique builds three-dimensional models
from liquid photosensitive polymers that
solidify when exposed to ultraviolet light.
Laser – concentrative UV beam to transom liquid into solid state.
Elevator – control the movement of platform upward and downward
Platform – a steel plate with plenty of holes as the basement for part building
Resin vat – contain raw material to form SLA model
Mirrors – control the path of movement of the laser beam at X and Y axis
Sensor – locate the coordinate and instant power of the laser beam and feedback to the control unit for fine adjustment
Mirrors
sensor
Advantages
◦ Flexibility of materials used
•
PVC, Nylon, Sand for building sand casting cores, metal
and investment casting wax.
◦ No need to create a structure to support the part
◦ Parts do not require any post curing except when ceramic is
used.
Disadvantages
◦ During solidification, additional powder may be hardened at
the border line.
◦ The roughness is most visible when parts contain sloping
(stepped) surfaces.
Application Range
As the name implies the process laminates
thin sheets of film (paper or plastic).
The laser has only to cut/scan the periphery of
each layer.
The process
The build material (paper
with a thermo-setting resin glue on its under side) is stretched from a supply roller across an anvil or platform to a take- up roller on the other side.
A heated roller passes over
the paper bonding it to the platform or previous layer.
A laser, focused to penetrate
through one thickness of paper cuts the profile of that layer. The excess paper
The process continued:
The process of gluing and cutting
continuous layer by layer until the
model is complete.
To reduce the build time, double or even
Advantages
o
Wide range of materials
o
Fast Build time
o
High accuracy
o
LOM objects are durable, multilayered structures which
can be machined, sanded, polished, coated and painted
Application Range
o
Used as precise patterns for secondary tooling processes
such as rubber molding, sand casting and direct
investment casting.
4. Fused Deposition Modeling
(FDM)
FDM 2000 Specifications Prodigy Specifications
Build Volume: 10" x 10" x 10" Materials: ABS, Casting Wax Build Step Size: 0.005" to 0.030"
Build Volume: 8" x 8" x 10" Materials: ABS, Casting Wax
(FDM) is a solid-based rapid prototyping method that
extrudes material, layer-by-layer, to build a model.
A thread of plastic is fed into an extrusion head,
where it is heated into a semi-liquid state and
extruded through a very small hole onto the previous
layer of material.
Support material is also laid down in a similar
Advantages
o
Easy fabrication
o
Minimal wastage
o
Ease of removal
o
Easy handling
Application Range
o
Designing
o
Engineering analysis and planning
How Rapid Prototyping Technologies
What is 3DP?
3DP
is the process of creating an object using a
machine that puts down material layer by
layer in three dimensions until the desired
object is formed. A 3D printer extrudes melted
plastic filament or other material, building
objects based on specifications that come
from modeling software or from a scan of an
existing object.
To create something with a 3D printer, a user begins either by
scanning an existing object with a 3D scanner to obtain the needed specifications or by generating the specs in a 3D modeling
application.
The specifications are then sent to an extrusion printer, where plastic
filament or other material is used to create the three-dimensional model one layer at a time.
As the material is extruded from the nozzle of the printer, the
software controlling the machine moves either the platform or the nozzle itself such that the material is deposited in a succession of layers to create the object. Often, the completed object is a single color, but printers are now available with two nozzles for dual-color prints. Printing can take a few minutes for a small object the size of a keychain or several hours for larger, more complicated objects.
3D Printed technology is being used by some of the most
modern manufacturers to develop prototypes and products
going through testing phase. This has increased the efficiency
of product development. These 3D printing innovations are
saving; time, money and resulting in higher profit margins.
3D printing technology is gaining in popularity, becoming
more competitive, and increasingly affordable. A lot of
businesses and industries are benefiting. Those employing
the new technology include manufacturers, print advertisers,
and commercial marketing firms who are reaching out to
clients with new brilliant ideas.
Some of the most exciting global businesses are already
expanding possibilities by using 3D printers. Coca-Cola
created
miniature statues of consumers to promote smaller Coke
bottles. Some of the other companies experimenting with the
technology are Nokia, Volkswagen, and eBay. In retail, say
Selfridges and
Harvey Nichols
in UK,
Le Bon Marché
in France,
to name a few.
Biscuits and chocolates
can now be 3D printed. It will be very
interesting for
food-related businesses
to see what their
marketers and printers are actually capable of with no holds
barred. Now companies can produce any design of biscuit with
extreme detailing. Since the technology is still very new and
modern, many will be attracted by the amazing designs and logo
printing. This makes these giveaways useful free samples at
While initially 3D printing was primarily a
technology for prototyping, this is quickly
changing. Now numerous manufacturers are
producing end-use components and entire
products via additive manufacturing. From the
aerospace industry, to medical modeling and
implantation, to prototyping of all kinds, 3D
printing is being used by virtually every major
industry on the planet in one way or another.
3D printed models of human organshave been a frequent tool for surgeons over the last two to three years, as they provide a more intricate view of the
issues at hand. Instead of relying on 2D and 3D images on a computer screen or a printout, surgeons can actually touch and feel physical replicas of the
patient’s organs, bone structures, or whatever else they are about to work on.
Additionally, there is research underway
by companies like Organ logy to 3D print partial human organs such as the liver and kidney.
Medical
3D bio printing, is a powerful fabrication technology, used to
create three-dimensional cellular constructs which bio mimics complex biological functionalities found in native tissues and organs.
The bio printing manufacturing technology combined with
smart biomaterials, stem cells, growth and differentiation
factors, and biomimetic environments have created
unique opportunities to fabricate tissues in the laboratory
from combinations of engineered extracellular matrices
(scaffolds), cells, and biologically active molecules.
Before
After
Actually, 3D printed drugs have a lot of
advantages to regularly manufactured ones. It’s
much easier to control density of a 3D printed
drug, and design how porous it should be, which
means that how quickly it dissolves is much for
flexible, and therefore, designers can print a pill
that can be dissolved with one sip of water.
Additionally, they can add more of the active
ingredient, all while making the actual pill much
smaller.
Another general early adopter of Rapid Prototyping
technologies, the earliest incarnation of 3D printing, was
the automotive sector. Many automotive companies
particularly at the cutting edge of motor sport and F1
have followed a similar trajectory to the aerospace
companies. First (and still) using the technologies for
prototyping applications, but developing and adapting
their manufacturing processes to incorporate the benefits
of improved materials and end results for automotive
parts.
Many automotive companies are now also looking at the
potential of 3D printing to fulfill after sales functions in
terms of production of spare/replacement parts, on
demand, rather than holding huge inventories.
Architectural models have long been a staple
application of 3D printing processes, for producing
accurate demonstration models of an architect’s
vision. 3D printing offers a relatively fast, easy and
economically viable method of producing detailed
models directly from 3D CAD, BIM or other digital
data that architects use. Many successful
architectural firms, now commonly use 3D printing
(in house or as a service) as a critical part of their
workflow for increased innovation and improved
communication.
Related technology development began in the 1960s, with
pumped concrete and isocyanine foams.
Building printing refers to various technology that use
3D printing as a way to construct buildings. Potential
advantages of this process include quicker construction, lower labor costs, and less waste produced. 3D printing at a large scale may be well suited for construction of extraterrestrial structures on the Moon or other planets where environmental conditions are less conducive to human labor-intensive
building practices.
Developments in additive manufacturing technologies have included attempts to make 3D printers capable of producing
structural buildings.
Related technology development began in the 1960s, with pumped concrete and isocyanine foams.
