ME 521
Computer Aided Design
4.2. CAD Output Devices-Rapid Prototyping
Assoc.Dr. Ahmet Zafer Şenalp
e-mail: azsenalp@gmail.com
Mechanical Engineering Department
Gebze Technical University
Rapid Prototyping
 It is the technology that using CAD models physical models are obtained directly.
For this purpose rapid prototyping devices are used.
 Although rapid prototyping devices vary in its group their principles are the same.
In this method physical models are formed by adding materials layer by layer.
 Rapid Prototyping (RP) brings solutions to the problems faced during product
development period.
 Possible design mistakes can easily be identified.
 Before the mass production, prototype has to be prepared and several tests have
to be conducted on these prototypes. This period may take a long time when
conducted with conventional methods. With RP this period is shortened and
prototypes can be tested both visually and functionally.
 Possible design changes can be decided on these prototypes and necessary
changes can easily be made.
 Prototypes can be used for die manufacturing.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
2
Rapid Prototyping
Where are the parts produced by RP used?
 After visual inspection possible shape mistakes can be identified.
 For products that contain more than one part perfect assembly conditions (ex:
alignment) can be checked.
 Mechanism functionality can be tested.
 An assembly with a lot of parts can be manufactured and run at one time.
 Prototypes can be used for die manufacturing .
 Prototype models can be used of precise casting.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
3
Rapid Prototyping
What kind of parts can be produced by RP?
 There is even no limitation to the parts that can be produced by RP. As the parts
can easily be bonded to each other, the size of the part is not a problem.
 Die production can also be made with RP.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
4
Rapid Prototyping
How much time is needed for RP?
Hours!...
Time needed for RP depends on complexity and volume of the part.
The delivery time is about 4-5 days after ordering.
In special cases the period can be short as 1 day or long as 10 days.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
5
Rapid Prototyping
Is RP expensive?
RP can be seen as expensive with the additional cost . However with RP the work that
could be concluded in weeks can be finished in hours.
Product defects can be detected earlier and much more expensive corrections can be
avoided. With these advantages apparent cost for RP is less than the savings made by
using RP.
The RP cost of products depends on factors like product size, volume and geometry.
Real cost of products should be determined after conducting necessary analysis.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
6
Rapid Prototyping
Rapid Prototyping Technologies:
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Polyjet
FDM: Fused Deposition Modeling
SLS: Selective Laser Sintering
SLA: Stereolithography
LOM: Laminated Object Manufacturing
EBM: Electron Beam Melting
3-D Printing
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
7
Polyjet
In this technique, photo-polymer material in liquid form at room temperature is sprayed from
spray nozzles of eight injection heads with thousands of injection spray nozzles which cause the
formation of layers (similar to plastic injection machines).
The sprayed material is freezed and solidified by using ultraviolet lamps.
16 micron thickness layers are formed one by one and prototype is obtained.
As the model can not stop hanging in the air, the
gaps are filled with support material with the same
injection method. This support material then
dissolves in water and the model is obtained.
The materials used in this technology are photopolymer resins which are specific to this method.
Physical and chemical properties differ from each
other.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
8
Polyjet
...... STL file is opened in the software and model is placed on the system’s
table and the file is send to the Polyjet from the software.
Polyjet system sprays the model and support material according to the
instructions send by the software.
After each layer sprayed material is applied ultraviolet rays for
solidification.
Model is constructed in 16 micron thickness layers. Then water spay is
used to remove support material from the model and prototype is
obtained.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
9
Polyjet
Polyjet Matrix
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
10
Polyjet
Polyjet Product Examples:
FullCure 720
Tango : TangoBlack &
TangoGray
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
11
Polyjet
Polyjet Product Examples:
Tango plus
Vero : VeroBlue,
VeroWhite,
VeroBlack
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
12
FDM: Fused Deposition Modeling
Fused deposition modeling (FDM) is an additive manufacturing technology commonly used for modeling,
prototyping, and production applications. The technology was developed by S. Scott Crump in the late
1980s and was commercialized in 1990.
The FDM fused deposition model process is additive which extrudes material in layers. A plastic filament is
melted and extruded through a heated nozzle. The nozzle moves to produce a profile of the part then
moves down and the next layer is built on top until the entire prototype model is fully built. The model is
complete and requires no hardening. FDM is an excellent choice for any 3D Model that needs to closely
represent the final product in strength and durability. CAD Models can be produced in about 24 hours
depending on the size and complexity. Online price quotes are available for FDM parts..
FDM requires support during the Prototype Model building
process and can increase the build time.
Several materials are available with different trade-offs
between strength and temperature properties. As well as
acrylonitrile butadiene styrene (ABS) polymer,
polycarbonates, polycaprolactone, polyphenylsulfones and
waxes. A "water-soluble" material can be used for making
temporary supports while manufacturing is in progress, this
soluble support material is quickly dissolved with specialized
mechanical agitation equipment utilizing a precisely heated
sodium hydroxide solution..
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
13
FDM: Fused Deposition Modeling
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
14
FDM: Fused Deposition Modeling
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
15
FDM: Fused Deposition Modeling
FDM Product Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
16
SLS: Selective Laser Sintering
Laser Sintering is also a technique by which parts are built layer by layer. The basic material
consists of powder with particle sizes in the order of magnitude of 50 µm. Successive powder
layers are spread on top of each other. After deposition, a computer controlled CO2 laser
beam scans the surface and selectively binds together the powder particles of the
corresponding cross section of the product. During laser exposure, the powder temperature
rises above the glass transition point after which adjacent particles flow together. This process
is called sintering.
After production of the part is completed powders
that function as support material are cleaaned by a
brush.
The material those are used in this technology are
Polyamide,
Ploystrene
and several metal alloys.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
17
SLS: Selective Laser Sintering
SLS Working Principle:
In sintering powder material is left under the melting temperature of the material
so that powders stick to each other.
4 phases of sintering can be seen in the above figure.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
18
SLS: Selective Laser Sintering
Best application areas of SLS technology
Mechanical and thermal test parts
Plastic parts
Large complex functional parts
Casting parts
Functional models
SLS Advantages
Products are resistant to shape and functional tests
Parts can be assembled with mechanic or chemical methods
No need to use support material
Parts are cleaner than other methods
Heat treatment or painting can be applied on the parts
The materials used
plastic, metal or ceramic powders can be used, as well as their mixtures consisting of
composite powders are also available. Glass fiber reinforced plastic powders or plasticcoated metal powders are examples to this.
In the case of metal usage
the method is called as Direct Metal Laser Sintering (DMLS).
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
19
SLS: Selective Laser Sintering
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
20
SLS: Selective Laser Sintering
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
21
SLS: Selective Laser Sintering
SLS Product Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
22
SLS: Selective Laser Sintering
SLS Product Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
23
SLS: Selective Laser Sintering
SLS Advantages
 SLS polyamide (nylon) material enables full
functional prototype production.
 Glass-filled nylon is resistant to high
temperature and chemical environments in the
prototype production.
 Rubber like parts can be manufactured
directly from polymer. This is for seals and
sealing elements that are exposed to high
temperature.
SLS Disadvantages
The surface finish of SLS parts are not good
as SLA parts but additional surface finish can be
applied.
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High shrinkage ratios can result torsion,
bending or dimensional inaccuracy.
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SLS feature details are not precise as in SLA.
 For durable metal parts and molded parts
P20 steel which is similar to St 200 can be used.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
24
SLA: Stereolithography
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Stereolithography is an additive manufacturing process using a
vat of liquid UV-curable photopolymer "resin" and a UV laser to
build parts a layer at a time. On each layer, the laser beam
traces a part cross-section pattern on the surface of the liquid
resin. Exposure to the UV laser light cures, or, solidifies the
pattern traced on the resin and adheres it to the layer below.
After a pattern has been traced, the SLA's elevator platform
descends by a single layer thickness, typically 0.05 mm to
0.15 mm (0.002" to 0.006"). Then, a resin-filled blade sweeps
across the part cross section, re-coating it with fresh material.
On this new liquid surface, the subsequent layer pattern is
traced, adhering to the previous layer. A complete 3-D part is
formed by this process. After building, parts are cleaned of
excess resin by immersion in a chemical bath and then cured in
a UV oven.
Stereolithography requires the use of support structures to
attach the part to the elevator platform and to prevent certain
geometry from not only deflecting due to gravity, but to also
accurately hold the 2-D cross sections in place such that they
resist lateral pressure from the re-coater blade. Supports are
generated automatically during the preparation of 3-D CAD
models for use on the stereolithography machine, although they
may be manipulated manually. Supports must be removed from
the finished product manually; this is not true for all rapid
prototyping technologies.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
25
SLA: Stereolithography
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
26
SLA: Stereolithography
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
27
SLA: Stereolithography
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
28
SLA: Stereolithography
SLA Part Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
29
SLA: Stereolithography
SLA Part Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
30
LOM:Laminated Object Manufacturing
Laminated object manufacturing (LOM) is a rapid prototyping system developed by Helisys
Inc. In it, layers of adhesive-coated paper, plastic, or metal laminates are successively glued
together and cut to shape with a knife or laser cutter.
The process is performed as follows:
1. Sheet is adhered to a substrate with a heated
roller.
2. Laser traces desired dimensions of prototype.
3. Laser cross hatches non-part area to facilitate
waste removal.
4. Platform with completed layer moves down out
of the way.
5. Fresh sheet of material is rolled into position.
6. Platform moves up into position to receive next
layer.
7. The process is repeated.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
31
LOM:Laminated Object Manufacturing
Advantages
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Low cost due to readily available raw material
Relatively large parts may be made, because no chemical reaction is necessary
Fast as laser only traces the contour and does not trace the whole cross section.
Parts can be used immediately after processing. There is no need for Additional processing.
No need for additional support.
It is easy to use.
Disadvantages
 The most common used material is still paper. The materials on any other specified is
currently underway.
 As parts are easily to accommodate to humidity finishing should be applied with a special
Epoxy based material (Lompoxy: generated for LOM usage).
 Production of complex parts are difficult.
 There may be fire problem when the working zone gets too hot.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
32
LOM:Laminated Object Manufacturing
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
33
LOM:Laminated Object Manufacturing
LOM Part Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
34
LOM:Laminated Object Manufacturing
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
35
EBM:Electron Beam Melting
Electron beam melting (EBM) is a type of additive manufacturing for metal parts. The
technology manufactures parts by melting metal powder layer per layer with an electron
beam in a high vacuum.
Unlike some metal sintering techniques, the parts are fully dense, void-free, and extremely
strong.
The vacuum environment in the EBM machine maintains the
chemical composition of the material and provides an excellent
environment for building parts with reactive materials such as
titanium alloys. The electron beam’s high power ensures a high
rate of deposition and an even temperature distribution within
the part, which gives a fully melted metal with excellent
mechanical and physical properties.
.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
36
EBM:Electron Beam Melting
Part surface quality is very good compared to other RP methods.
Can be applicable to metals, materials apart from metals, ceramics and composite
materials.
EBM is successful in small and parts with precise regions.
Can drill holes with one or two nanometer precision.
More precise than metal cutting operations.
The part can directly be used after the operation.
No need for extra heat treatment
SLS,LSM,DMLS needs heat treatment.
 Due to high energy and scanning method EBM is very fast.
 Minimum layer thickness: 0.05 mm
Tolerance: +/-0,4 mm.
Very successful in titanium alloys.
Applied to medical implants, aerospace/automotive parts successfully.
In this method parts are produced within hours.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
37
EBM:Electron Beam Melting
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
38
EBM:Electron Beam Melting
EBM application with Ti6AI4V material
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
39
EBM:Electron Beam Melting
Advantages
Obtaining high energy with narrow beam.
The quality of the vacuum melting enables high material properties.
Vacuum environment avoids oxide and nitride based impurities.
Enables welding of unlike metals that are hard to process.
Comparison with SLS:
Due to efficient beam formation power consumption is low
Maintenance and installation costs are lower
It has high power and speed
Bending of the beam is obtained without moving the part which results high speed
and low maintenance.
Disadvantages
Vacuum requirement means additional cost.
Emits gamma rays during operation (Vacuum tanks should be designed to protect rays)
Materials should have electric conductive property.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
40
EBM:Electron Beam Melting
EBM Part Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
41
3D Printing
Developed in MIT (Massachusetts Institute of Technology).
3D parts is produced layer by layer.
 3D printers are generally fast and have low costs.
 One version of 3D printing includes inkjet printing system.
Fine dust material (plaster, resin) is sprayed from the printer and adhesive is then used for
bonding.
This technology enables the production of fully colorful prototypes.
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
42
3-D Printing
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
43
3-D Printing
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
44
3-D Printing
3-D Printing Part Examples:
Dr. Ahmet Zafer Şenalp
ME 521
Mechanical Engineering Department,
GTU
45
Rapid Prototyping
RP Technology comrarison
Dr. Ahmet Zafer Şenalp
ME 521
(lower grade is better)
Mechanical Engineering Department,
GTU
46