Transcript No Slide Title

RAPID PROTOTYPING
TECHNOLOGIES
Prof. Dr. Bilgin KAFTANOĞLU
www.mfge.atilim.edu.tr/kaftanoglu
Manufacturing Engineering Department
ATILIM UNIVERSITY
ANKARA
2009
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WHAT IS PROTOTYPING?
 Essential part of the product
development and manufactuing cycle;
 Assesing the form, fit and functionality
of a design before a significant investment
in tooling is made.
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Until Recently, prototypes:
 were handmade by skilled craftsmen (i.e. High Cost);
 adding weeks or months to the product development
time (increase time to market)
So:
 A few design iterations could be made before
tooling went into production;
 Seldom optimization of designed parts or at worst
parts did not function properly.
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Rapid Prototyping:
 name given to a host of related technologies that are
used to fabricate physical objects directly from CAD data
sources;
 These methods are unique in that they add and bond
materials in layers to form objects.
 Other names: Solid Freeform Fabrication,Layer
Manufacturing
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With Rapid Prototyping,
 Objects can be formed with any geometric complexity
without the need for elaborate (very complex) machine setup
and jigs and fixtures.
 Objects can be made from multiple materials (Such as
Aluminum and Polyamide, Copper and Steel), or as
composites, or materials can even be varied in a controlled
fashion at any location in an object;
 The construction of complex objects are reduced to a
manageable, straightforward, and relatively fast process.
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With Rapid Prototyping,
 time to market in manufacturing is reduced;
 the product designs are better understood and
communicated;
 rapid tooling to manufacture those products are made.
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The names of specific Rapid Prototyping processes:
• Stereolithography (SLA),
• Selective laser sintering (SLS),
• Fused deposition modeling (FDM),
• Laminated object manufacturing (LOM),
• Laser Engineering Net Shaping (LENS)
• Inkjet Systems and Three Dimensional Printing (3DP).
Each has its singular strengths and weaknesses.
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STEREOLITHOGRAPHY
• The most widely used rapid prototyping technology.
• Builds plastic parts or objects a layer at a time by
tracing a laser beam on the surface of a vat of liquid
photopolymer (Self Adhesive Material).
• Liquid photoplymer quickly solidifies wherever the
laser beam strikes the surface of the liquid.
• Once one layer is completely traced, it's lowered a
small distance into the vat and a second layer is traced
right on top of the first.
• The layers bond to one another and form a complete,
three-dimensional object after many such layers are
formed.
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STEREOLITHOGRAPHY
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The platform in the tank of photopolymer at the beginning of a run.
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STEREOLITHOGRAPHY
The objects have overhangs
or undercuts which must be
supported during the
fabrication process by support
structures.
These are either manually or
automatically designed and
fabricated right along with the
object. Upon completion of the
fabrication process, the object
is elevated from the vat and
the supports are cut off.
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The platform at the end of a print run,
shown here with several identical objects.
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STEREOLITHOGRAPHY
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STEREOLITHOGRAPHY
 The second most accurate and best surface
finish of any rapid prototyping technology.
 Wide range of materials with properties
mimicking those of several engineering
thermoplastics. Biomedical materials are
available, and ceramic materials are currently
being developed.
 The technology is also notable for the large
object sizes that are possible.
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STEREOLITHOGRAPHY
On the negative side,
 Material is expensive,
smelly and toxic;
Removing supports may
adversely effect surface
finish;
Parts often require a postcuring operation in a
separate oven-like
apparatus for complete cure
and stability. Post Curing
ensures that no liquid or
partially cured resin remains.
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The ultraviolet "oven" used to cure
completed objects.
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FUSED DEPOSITION MODELLING
• Second most widely used rapid prototyping
technology, after stereolithography
• A plastic filament is unwound from a coil and
supplies material to an extrusion nozzle.
The nozzle:
• is heated to melt the plastic and has a
mechanism which allows the flow of the melted
plastic to be turned on and off.
• is mounted to a mechanical stage which can be
moved in both horizontal and vertical directions.
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FUSED DEPOSITION MODELLING
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FUSED DEPOSITION MODELLING
• As the nozzle is moved over the table in the
required geometry, it deposits a thin bead of
extruded plastic to form each layer.
• The plastic hardens immediately after being
extruded and bonds to the layer below.
• The chamber is held at a temperature just
below the melting point of the plastic.
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FUSED DEPOSITION MODELLING
 Materials: ABS and investment casting wax, and more
recently polyamide materials;
 Researches for embedding Ceramic and Metal powders in
polymer filament is going on.
 ABS offers good strength;
 Support materials:
Same material: Problems during removing;
 Break Away Support System: Easily removed;
 Water Works: Water-soluble support material.
(in ultrasonic vibration tank)
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FUSED DEPOSITION MODELLING
• Office-friendly and quiet;
• Fairly fast for small parts or for those that have
tall, thin form-factors;
• Very slow for parts with wide cross sections;
• The finish of parts have been greatly improved
over the years, but aren't quite on a par with
stereolithography.
• FDM offers great strength.
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INKJET
• Uses a single jet each for a plastic build
material and a wax-like support material, which
are held in a melted liquid state in reservoirs
• The materials harden by rapidly dropping in
temperature as they are deposited
• After an entire layer of the object is formed by
jetting, a milling head is passed over the layer to
make it a uniform thickness
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INKJET
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INKJET
• Extremely fine resolution and surface finishes,
essentially equivalent to CNC machines;
• The technique is very slow for large objects;
• While the size of the machine and materials are
office-friendly, the use of a milling head creates noise
which may be objectionable in an office environment.
• Materials selection is very limited and the parts are
fragile
• Especially used in precise casting patterns for
jewelry.
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INKJET
Jevelry Application
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A production cut in the middle
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3D PRINTING
• Developed at MIT;
• A measured quantity of powder is first dispensed from a
similar supply chamber by moving a piston upward
incrementally.
• The roller then distributes and compresses the powder
at the top of the fabrication chamber.
• The jetting head subsequently deposits a liquid
adhesive in a two dimensional pattern onto the layer of
the powder
•The powder becomes bonded in the areas where the
adhesive is deposited, to form a layer of the object.
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3D PRINTING
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3D PRINTING
• No external supports are required during fabrication
since the powder bed supports overhangs;
• Offers the advantages of speedy fabrication and low
materials cost;
• Probably the fastest of all RP methods;
• Recently color output has also become available;
• There are limitations on resolution, surface finish, part
fragility and available materials.
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LAMINATED OBJECT MANUFACTURING
• object cross sections are cut from paper or other web
material using a laser or a knife;
• The paper is unwound from a feed roll onto the stack
and first bonded to the previous layer using a heated
roller which melts a plastic coating on the bottom side of
the paper
• The profiles are then traced by an optics system or knife
• Areas to be removed in the final object are heavily
cross-hatched with the laser to facilitate removal.
• Excess paper is cut away to separate the layer from the
web. Waste paper is wound on a take-up roll
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LAMINATED OBJECT MANUFACTURING
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LAMINATED OBJECT MANUFACTURING
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LAMINATED OBJECT MANUFACTURING
• It can be time consuming to remove extra material for
some geometries;
• The finish, accuracy and stability of paper objects are
not as good as for materials used with other RP methods
• Material costs are very low, and objects have the look
and feel of wood and can be worked and finished in the
same manner
• Application: Patterns for sand castings.
• Limitations on materials, work has been done with
plastics, composites, ceramics and metals. However,
available on a limited commercial basis.
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Laser Engineered Net Shaping
• A technology that is gaining in importance and in early
stages of commercialization.
• Designed for aerospace industry, especially to produce
titanium parts.
• A high power laser (1400 W) is used to melt metal
powder supplied coaxially to the focus of the laser beam
through a deposition head.
•The head is moved up vertically as each layer is
completed.
• Metal powders are delivered and distributed around the
circumference of the head either by gravity, or by using a
pressurized carrier gas.
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Laser Engineered Net Shaping
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Laser Engineered Net Shaping
• In addition to titanium, a variety of materials can be
used such as stainless steel, copper, aluminum etc.
• Materials composition can be changed dynamically
and continuously, leading to objects with properties
that might be mutually exclusive using classical
fabrication methods.
• Has the ability to fabricate fully-dense metal parts
with good metallurgical properties at reasonable
speeds;
• Objects fabricated are near net shape, but
generally will require finish machining.
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Laser Engineered Net Shaping
Before and after finish machining
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Laser Engineered Net Shaping
120x120x120 cm LENS Machine
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Selective Laser Sintering
Sintering:
• bonding of the metal, ceramic or plastic powders
together when heated to temperatures in excess of
approxiamately half the absolute melting tempertaure.
• In the industry, sintering is mainly used for metal and
ceramic parts (Powder Matallurgy).
• After pressing (compaction) of the powder inside mold
for deforming into high densities, while providing the
shape and dimensional control, the compacted parts are
then sintered for achieving bonding of the powders
metallurgically.
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Selective Laser Sintering
Compaction
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Sintering
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SINTERING
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Sintering in Rapid Prototyping
Sintering process used in Rapid Prototyping differs from
the Powder Metallurgy, such as:
• Plastic based powders, in additon to metal powders.
• Local sintering, not overall sintering.
• Very short sintering period.
Laser (heat source) is exposed to sections to be
sintered for a very short time. Hard to achive an
ideal sintering.
In some applications, for achieving the ideal
sintering, the finished parts are heated in a
seperate sintering owen.
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Selective Laser Sintering
• Invented by Carl Deckard during his Phd. studies in Texas
University in 1987.
• Offers the key advantage of making functional parts in
essentially final materials.
• The system is mechanically more complex than
stereolithography and most other technologies.
• A variety of thermoplastic materials such as nylon, glass
filled nylon, polyamide and polystyrene are available. The
method has also been extended to provide direct fabrication of
metal and ceramic objects and tools.
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Selective Laser Sintering
Process:
1) Laser beam is traced
over the surface the tightly
compacted powder to
selectively melt and bond it
to form a layer of the object.
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Selective Laser Sintering
Process:
2) Platform is lovered down
one object layer thickness
to accommodate the new
layer of powder
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Selective Laser Sintering
Process:
3) A new layer of powder is
coated on the surface of
the build chamber.
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Selective Laser Sintering
Process:
4) The powder is supplied
from the powder bins to the
recoater.
This process is repeated
until the entire object is
fabricated.
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Selective Laser Sintering
• The fabrication chamber is maintained at a temperature
just below the melting point of the powder
• Heat from the laser need only elevate the temperature
slightly to cause sintering. This greatly speeds up the
process;
• No supports are required with this method since
overhangs and undercuts are supported by the solid
powder bed;
• Surface finishes and accuracy are not quite as good as
with stereolithography, but material properties can be
quite close to those of the intrinsic materials
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Selective Laser Sintering
Three Types of Laser Sintering Machines:
1) Plastic Laser Sintering Machine
2) Metal Laser Sintering Machine
3) Sand Casting Laser Sintering Machine
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Selective Laser Sintering
Plastic Laser Sintering:
• For direct
manufacture of styling
models, functional
prototypes, patterns for
plaster, investment and
vacuum casting, for
end products and spare
parts.
• Volvo Steering Wheel
• Engine Block Pattern
• Plaster Invest. Pattern
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Selective Laser Sintering
Metal Laser Sintering:
• For direct production
of tooling, including for
plastic injection
molding, metal die
casting, sheet metal
forming as well as
metal parts, directly
from steel based and
other metal powders.
• A gear for Volvo Corp.
• Die Cast Parts (500 Al
parts produced)
• Motor Housing
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Selective Laser Sintering
Sand Laser Sintering:
• Laser Sintering
System for direct,
boxless manufacture
of sand cores and
moulds for metal
casting.
•V6-24 Valve Cylinder
Head.
• Impeller
• Steering Block for a car
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METU SYSTEM

EOS EOSINT P380 Rapid Prototyping System
General Properties
Plastic Laser Sintering System
X,Y Axes Alternating Scanning
Technical Specifications
Work Envelope:
-X Axis: 340 mm
-Y Axis : 340 mm
-Z Axis : 600 mm
Layer Forming Thickness:
0.15mm +/-0.05 mm
Max Laser Power: 50 W
Z Axis Production Speed: 30 mm / saat
Max Scanning Speed: 5 m/s
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Comparison Chart
TECHNOLOGY
SLA
SLS
FDM
INKJET
3D PRINTER
LOM
Max Part Size (cm)
30x30x50
34x34x60
30x30x50
30x15x21
30x30x40
65x55x40
Speed
average
average to fair
poor
poor
excellent
good
Accuracy
very good
good
fair
excellent
fair
fair
Surface Finish
very good
fair
fair
excellent
fair
fair to poor
Strengths
Weaknesses
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market
market leader,
leader,
accuracy,
office okay,
large part
materials,
price,
size,
large part
materials
accuracy,
size.
wide product
size and
post
weight,
processing,
speed
system price,
messy liquids
surface finish
accuracy,
finish,
office okay
speed,
limited
materials,
part size
large part
size,
good for
large
castings,
material cost
limited
part stability,
materials,
smoke,
fragile parts,
finish and
finish
accuracy
speed,
office okay,
price,
color,
price
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Additive Fabrication vs Subtractive
Fabrication
• Additive Fabrication methods (RP) can not become complete
replacement for the Subtractive Fabrication methods (Milling,
Turning, EDM etc.)
• Subtractive methods:
• have reached an extraordinary level of development and they
continue to evolve.
• they are fast, versatile, inexpensive, readily available and wellunderstood by large numbers of practitioners.
• in many cases they are quite sufficient to make prototypes
rapidly,
• no equal when it's necessary to make very precise parts in final
materials.
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Additive Fabrication vs Subtractive
Fabrication
• Additive technologies are instead complementary to subtractive ones, if
the situation calls for:
1.complex or intricate geometric forms,
2.simultaneous fabrication of multiple parts into a single assembly,
3.multiple materials or composite materials in the same part.
Additive technologies make it possible to completely control
the composition of a part at every geometric location. Thus, RP
is the enabling technology for controlled material composition
as well as for geometric control.
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Limitations of RP Methods
1) ACCURACY
•
Stair Stepping:
Since rapid prototyping builds object in layers, there
is inevitably a "stairstepping" effect produced because
the layers have a finite thickness.
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Limitations of RP Methods
1) ACCURACY
Precision:
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tolerances are still not quite at the level of CNC,
•
Because of intervening energy exchanges and/or
complex chemistry one cannot say with any certainty
that one method of RP is always more accurate than
another, or that a particular method always produces a
certain tolerance.
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Limitations of RP Methods
1) FINISH
The finish and appearance of a part are related to accuracy, but
also depend on the method of RP employed. Technologies based
on powders have a sandy or diffuse appearance, sheet-based
methods might be considered poorer in finish because the
stairstepping is more pronounced.
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Limitations of RP Methods
1) Secondary Operations
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Parts made by stereolithography are frequently not completely
cured when removed from the machine. Final cure is effected in a
box called a post-cure apparatus (PCA)
•
Parts made by three dimensional printing (3DP) and MultiJet
Modeling (MJM) can be very fragile and might not be able to take
normal handling or shipping stresses. These parts are often
infiltrated with cyanoacrylate adhesive or wax as a secondary
operation to make them more durable.
•
Metal parts will almost certainly require final machining and must
usually undergo a thermal baking cycle to sinter and infiltrate
them with a material to make them fully-dense.
•
Other than powder-based methods all other methods require a
support structure to be removed in a secondary operation which
may require considerable effort and time.
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Limitations of RP Methods
Support structure (red material), watersoluble, fused deposition modeling (FDM).
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Support structure, stereolithography.
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Limitations of RP Methods
3) SYSTEM COSTS
RP systems cost from $30,000 to $800,000 when
purchased new. The least expensive are 3D Printer and
FDM systems; the most expensive are specialized
stereolithography machines.
In addition, there are appreciable costs associated with
training, housing and maintenance. For example it can cost
more than $20,000 to replace a laser in a stereolithography
system.
4) Material
High cost. Available choices are limited.
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RP in Medical Applications
Oral Surgery
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RP in Medical Applications
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RP in Medical Applications
Modelling in Medical Applications:
Models are created using medical imaging data
obtained from
• a standard Computed Tomography (CT) or
• Magnetic Resonance Imaging (MRI).
Bone structures such as skull or pelvis are all
imaged using CT. Soft tissue structures such as
brain and organs are best imaged by MRI. The
“slice” data from CT or MRI are processed into 3D
images by using sophisticated software.
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RP in Medical Applications
Oral Surgery
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RP in Medical Applications
Oral Surgery
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RP in Medical Applications
Prosthesis Applications
A bone structure which was produced from ceramic
powder embedded paper material in LOM.
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RP in Medical Applications
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RP in Medical Applications
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RP in Medical Applications
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RP in Medical Applications
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RP in Medical Applications
Bone Structure with the cranial vasculature
highlighted in red. This model was made using SLS
with a special material called Stereocol.
(Coloured when exposed to high power laser)
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RP in Medical Applications
TISSUE ENGINEERING
Actual living tissue cells are extracted from the patient and seeded onto a
carrier which accomodates and guides the growth of new cells in 3D within
laboratory environment.
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RP in Medical Applications
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THANK
YOU!
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