20ME605B

PROFESSINAL ELECTIVE-II
ADVANCED MANUFACTURING
PROCESSES
Semester 6
BE Mechanical Engineering
Lecture-13
Department of Mechanical Engineering,
GSFC University
Expert Lecture
Books to be referred
Reference book
• Additive Manufacturing
Technologies Rapid
Prototyping to Direct Digital
Manufacturing
• I. Gibson l D. W. Rosen l B.
Stucker
• ISBN: 978-1-4419-1119-3
• e-ISBN: 978-1-4419-1120-9
DOI: 10.1007/978-1-4419-
1120-9
• Springer New York Heidelberg
Dordrecht London
Reference book
• Additive Manufacturing
Innovations, Advances, and
Applications
• Edited by:
t.S. Srivatsan; t.S.Sudarshan
• CRC Press Taylor & Francis
Group 6000 Broken Sound
Parkway NW, Suite 300 Boca
Raton, FL 33487-2742
Reference book
• ADDITIVE AND
TRADITIONALLY
MANUFACTURED
COMPONENTS
• A Comparative Analysis of
Mechanical Properties
• JOSHUA PELLEG Materials
Engineering Department Ben
Gurion University of the Negev,
Beer Sheva, Israel
• Elsevier Radarweg 29, PO Box 211,
1000 AE Amsterdam, Netherlands
The Boulevard, Langford Lane,
Kidlington, Oxford OX5 1GB,
United Kingdom 50 Hampshire
Street, 5th Floor, Cambridge, MA
02139, United States
 1986???
• What many people don't actually know is that 3D printing is not a new
technology.
• In fact, the first-ever patent for 3D printing was successfully issued in
1986.
• Let's take a closer look at the history of 3D printing and how it all
came about.
Dr. Hideo Kodama
 Japan
• The history of 3D printing begins in 1981 with Dr. Hideo Kodama’s
patent application for a rapid prototyping device. As far as we’re
aware, Dr. Kodama is the first person ever to apply for a patent in
which laser beam resin curing system is described.
• Unfortunately, the Japanese doctor’s application never went through.
Due to issues with funding, he was unable to complete the process
before the one-year deadline.

https://all3dp.com/2/history-of-3d-printing-when-was-3d-printing-invented/
The SLA 1
 1984-1988

• 1984 was the lucky year for 3D printing. Working for a tabletop and
furniture manufacturer, Charles “Chuck” Hull was frustrated at the long
times it took to make small, custom parts. He therefore suggested turning
the company’s UV lamps to a different use: curing photosensitive resin
layer-by-layer, eventually creating a part. (Sound familiar?)
• Fortunately, Hull was given his own small lab to work on the process. Only
three weeks after the team in France applied for their patent, Hull applied
for his, calling the technology stereolithography.
• The patent was issued in 1986, and in the same year, Charles started his
own company in Valencia, California: 3D Systems. They released their first
commercial product, the SLA-1, in 1988.
 1988-1992
1988-1992
 Mr. Chuck Hull

• 1986: Chuck Hull invents stereo lithography apparatus (SLA). This

3D printing technique refers to a method of printing objects layer by
layer using a process in which lasers selectively cause chains of
molecules to link together, forming polymers.
• Hull goes on to go-found 3D Systems Corporation, which introduces
the world’s first commercial 3D printing system, the SLA-1.
Patent
1st Patent By Mr. Chuck Hull in 1986
1st Patent By Mr. Chuck Hull in 1986
 1st Patent By Mr. Chuck Hull in 1986
Abstract
 SLS
• In 1988, the same year that the SLA-1 was introduced, another 3D
printing technology was invented. This time, it was selective laser
sintering (SLS), the patent for which was filed by Carl Deckard, an
undergraduate at the University of Texas.
• Deckard’s machine, the first SLS 3D printer, was called Betsy. It was
able to produce only simple chunks of plastic. However, as the main
purpose of the printer was to test the idea for the SLS, object details
and print quality weren’t the highest priorities.
FDM FDM
• In the meantime, while the patent for SLS was awaiting approval,
another patent for an additive manufacturing technology was
submitted to the US government.
• This time it was for fused deposition modeling (FDM). Interestingly,
despite now being the simplest and most common of the three
technologies, FDM was actually invented after SLA and SLS.
• The patent for FDM was submitted by Scott Crump, who is today well
known for being the co-founder of Stratasys. Founded in 1989, the
Minnesota-based company is one of the market leaders for high
precision 3D printers.
STEREOLITHOGRAPHY (SLA) 3D PRINTING
Components
STEREOLITHOGRAPHY (SLA) 3D PRINTING
Components
STEREOLITHOGRAPHY (SLA) 3D PRINTING
Components
• Every standard SLA 3D printer is generally composed of four primary
sections:
• A tank filled with the liquid photopolymer: The liquid resin is usually
a clear and liquid plastic.
• A perforated platform immersed in a tank: The platform is lowered
into the tank and can move up and down according to the printing
process.
• A high-powered, ultraviolet laser
• A computer interface, which manages both the platform and the laser
movements
Additive Manufacturing
• Additive manufacturing is the formalized term for what used to be called
rapid prototyping and what is popularly called 3D Printing.
• The term rapid prototyping (RP) is used in a variety of industries to describe a
process for rapidly creating a system or part representation before final release
or commercialization.
• In other words, the emphasis is on creating something quickly and that the
output is a prototype or basis model from which further models and eventually
the final product will be derived.
• Management consultants and software engineers both also use the term rapid
prototyping to describe a process of developing business and software
solutions in a piecewise fashion that allows clients and other stakeholders to
test ideas and provide feedback during the development process.
Process chain
 Introduction to
3D Modelling
for
Additive Manufacturing
Methods for making base shapes in 3D
modelling….!!!
Extrude
Revolve
Sweep
Loft
Helix
Booleans
Extrude
Extrude
Extrude
Extrude
Extrude
Extrude
Extrude
Revolve
Revolve
Revolve
Sweep
Loft
Helical Sweep
Helical Sweep
Booleans
Booleans
Booleans
CLASSIFICATION OF RAPID PROTOTYPING
SYSTEMS
(1) liquid-based
(2) solid-based and
(3) Powder based
 Liquid-Based

(1) 3D Systems’ Stereolithography Apparatus (8) Denken’s SLP

(SLA) (9) Mitsui’s COLAMM
(2) Cubital’s Solid Ground Curing (SGC) (10) Fockele & Schwarze’s LMS
(3) Sony’s Solid Creation System (SCS) (11) Light Sculpting
(12) Aaroflex
(4) CMET’s Solid Object Ultraviolet-Laser Printer
(SOUP) (13) Rapid Freeze
(14) Two Laser Beams
(5) Autostrade’s E-Darts (15) Microfabrication
(6) Teijin Seiki’s Soliform System
(7) Meiko’s Rapid Prototyping System for the
Jewelry Industry
 Solid-Based
(1) Cubic Technologies’ Laminated Object Manufacturing (LOM)
(2) Stratasys’ Fused Deposition Modeling (FDM)
(3) Kira Corporation’s Paper Lamination Technology (PLT)
(4) 3D Systems’ Multi-Jet Modeling System (MJM)
(5) Solids cape's Model Maker and Pattern Master
(6) Beijing Yinhua’s Slicing Solid Manufacturing (SSM),
Melted Extrusion Modeling (MEM) and
Multi-Functional RPM Systems (M-RPM)
(7) CAM-LEM’s CL 100
(8) Ennex Corporation’s Offset Fabbers
 Powder-Based
(1) 3D Systems’s Selective Laser Sintering (SLS) (8) Aeromet Corporation’s Lasform
(2) EOS’s EOSINT Systems Technology
(3) Z Corporation’s Three-Dimensional Printing (9) Precision Optical Manufacturing’s
(3DP) Direct Metal Deposition
(4) Optomec’s Laser Engineered Net Shaping (DMDTM)
(LENS) (10) Generis’ RP Systems (GS)
(5) Soligen’s Direct Shell Production Casting (11) Therics Inc.’s Theriform
(DSPC) Technology
(6) Fraunhofer’s Multiphase Jet Solidification (MJS) (12) Extrude Hone’s PrometalTM 3D
(7) Acram’s Electron Beam Melting (EBM) Printing Process
 DATA CONVERSION AND TRANSMISSION
• The STL file format approximates the surfaces of the model using tiny
triangles.
• Highly curved surfaces must employ many more triangles, which
mean that STL files for curved parts can be very large.
• Where necessary, supports are also converted to a separate STL file.
• Data transmission via agreed data formats such as STL or IGES may
be carried out through a diskette,
• email(electronic mail) or LAN (local area network).
• No validation of the quality of the STL files is carried out at this stage.
 CHECKING AND PREPARING
“garbage in garbage out”
• Today’s CAD models — whose quality are dependent on the CAD systems,
human operators and
• Post processes — are still afflicted with a wide spectrum of problems,
including the generation of unwanted shell-punctures (i.e. holes, gaps,
cracks, etc.)
• The CAD model errors are corrected by human operators assisted by
specialized software.
• This process of manual repair is very tedious and time consuming especially
if one considers the great number of geometric entities (e.g. triangular
facets) that are encountered in a CAD model.
 CHECKING AND PREPARING

• Once the STL files are verified to be error-free, the RP system’s

computer analyses the STL files that define the model to be fabricated
and slices the model into cross-sections.
• They also include the determination of technological parameters such
as cure depth, laser power and other physical parameters as in the case
of SLA.
• Many vendors are continually working to improve their systems in this
aspect.
setting parameters
 BUILDING
• The building process may take up to several hours to build depending
on the size and number of parts required.
• The number of identical parts that can be built is subject to the overall
build size constrained by the build volume of the RP system.
 POSTPROCESSING
• The final task in the process chain is the post processing task. At this stage,
generally some manual operations are necessary.
• As a result, the danger of damaging a part is particularly high.
• Therefore, the operator for this last process step has a high responsibility for
the successful process realization.
• The cleaning task refers to the removal of excess parts which may have
remained on the part.
• Thus, for SLA parts, this refers to excess resin residing in entrapped portion
such as a blind hole of a part, as well as the removal of supports.
• Similarly, for SLS parts, the excess powder has to be removed. Likewise for
LOM, pieces of excess wood like blocks of paper which acted as supports
have to be removed.
 LIQUID-BASED
RAPID PROTOTYPING SYSTEMS
• Most liquid-based rapid prototyping systems build parts in a vat of photo-
curable liquid resin, an organic resin that cures or solidifies under the effect
of exposure to laser radiation, usually in the UV range.
• The laser cures the resin near the surface, forming a hardened layer. When a
layer of the part is formed, it is lowered by an elevation control system to
allow the next layer of resin to be similarly formed over it.
• This continues until the entire part is completed.
• The vat can then be drained and the part removed for further processing, if
necessary.
• There are variations to this technique by the various vendors and they are
dependent on the type of light or laser, method of scanning or exposure,
type of liquid resin, type of elevation and optical system used.
 Photo polymerization
• Photo polymerization processes make use of liquid, radiation-curable
resins, or photopolymers, as their primary materials.
• Most photopolymers react to radiation in the ultraviolet (UV) range of
wavelengths, but some visible light systems are used as well.
• Upon irradiation, these materials undergo a chemical reaction to
become solid.
• This reaction is called photo polymerization, and is typically complex,
involving many chemical participants.
History of Photopolymers
• Photopolymers were developed in the late 1960s and soon became widely
applied in several commercial areas, most notably the coating and printing
industry.
• Many of the glossy coatings on paper and cardboard, for example, are
photopolymers.
• Additionally, photo-curable resins are used in dentistry, such as for sealing
the top surfaces of teeth to fill in deep grooves and prevent cavities.
• In these applications, coatings are cured by radiation that blankets the resin
without the need for patterning either the material or the radiation.
• This changed with the introduction of stereo lithography.
History of Photopolymers

• In the mid-1980s, Charles (Chuck) Hull was experimenting with UV-

curable materials by exposing them to a scanning laser, similar to the
system found in laser printers.
• He discovered that solid polymer patterns could be produced. By
curing one layer over a previous layer, he could fabricate a solid 3D
part.
• The term “vat photo polymerization” is a general term that
encompasses SL and these related processes.
• SL will be used to refer specifically to macroscale, laser scan vat photo
polymerization; otherwise, the term vat polymerization will be used
and will be abbreviated as VP.
 configurations for
photo polymerization processes
• Vector scan, or point-wise, approaches typical of commercial SL
machines
• Mask projection, or layer-wise, approaches, that irradiate entire
layers at one time, and
• Two-photon approaches that are essentially high resolution point-
by-point approaches
Vector scan Stereo lithography
Mask Projection
Two photon approach
 Photopolymerization Materials
• UV Curable Photopolymers [three polymer Structures]
 Types of radiation
• Gamma rays, • only UV and visible light systems are utilized in
• X-rays, commercial systems.
• General SL systems use UV light.
• Electron beams, • SLA-250 Use helium-cadmium (HeCd)
• UV , laser.(wavelength of 325 nm)
• Visible light, and • other SL models Use solid state laser Nd-YVO4.
• mask projection DMD-based systems uses UV
• Electron beam and visible-light Radiation.
Photopolymer Chemistry
• SL photopolymers are composed of
• Photo initiators,
• reactive diluents,
• flexibilizers,
• stabilizers, and
• liquid monomers.
Solid based technique
LAMINATED OBJECT MANUFACTURING
(LOMTM)
LOM process
Process
In the building phase, thin layers of adhesive-coated material are
sequentially bonded to each other and individually cut by a CO2 laser
beam. The build cycle has the following steps:
(1) LOMSliceTM creates a cross-section of the 3D model measuring the
exact height of the model and slices the horizontal plane
accordingly. The software then images crosshatches which define
the outer perimeter and convert these excess materials into a
support structure.
(2) The computer generates precise calculations, which guide the
focused laser beam to cut the cross-sectional outline, the
crosshatches, and the model’s perimeter. The laser beam power is
designed to cut exactly the thickness of one layer of material at a
time. After the perimeter is burned, everything within the model’s
boundary is “freed” from the remaining sheet.
Process
• The platform with the stack of previously formed layers descends and
a new section of material advances. The platform ascends and the
heated roller laminates the material to the stack with a single
reciprocal motion, thereby bonding it to the previous layer.
• The vertical encoder measures the height of the stack and relays the
new height to LOMSliceTM, which calculates the cross section for the
next layer as the laser cuts the model’s current layer.
 Post Processing
1) The metal platform, home to the newly created part, is removed from
the LOMTM machine. A forklift may be needed to remove the larger
and heavier parts from the LOM-2030HTM.
2) Normally a hammer and a putty knife are all that is required to separate
the LOMTM block from the platform. However, a live thin wire may
also be used to slice through the double-sided foam tape, which serves
as the connecting point between the LOMTM stack and the platform.
3) The surrounding wall frame is lifted off the block to expose the
crosshatched pieces of the excess material. Crosshatched pieces may
then be separated from the part using wood carving tools.
Post processing

(a) The laminated stack is removed from the machine’s elevator plate.
(b) The surrounding wall is lifted off the object to expose cubes of excess material.
 Post processing

(c) Cubes are easily separated from the object’s surface.

(d) The object’s surface can then be sanded, polished or painted, as desired.
After the part is extracted from surrounding crosshatches the wood like
LOMTM part can be finished. Traditional model-making finishing
techniques, such as sanding, polishing, painting, etc. can be applied.
After the part has been separated it is recommended that it be sealed
immediately with urethane, epoxy, or silicon spray to prevent moisture
absorption and expansion of the part. If necessary, LOMTM parts can be
machined — by drilling, milling and turning.
Materials
Potentially, any sheet material with adhesive backing can be utilized in
Laminated Object Manufacturing. It has been demonstrated that
plastics, metals, and even ceramic tapes can be used. However, the most
popular material has been Kraft paper with a polyethylene-based heat
seal adhesive system because it is widely available, cost-effective, and
environmentally benign.
In order to maintain uniform lamination across the entire working
envelope it is critical that the temperature remain constant. A
temperature control system, with closed-loop feedback, ensures the
system’s temperature remains constant, regardless of its surrounding
environment.
Case study 1
• An Experimental Investigation of the Tensile Strength of Parts
Produced by Laminated Object Manufacturing (LOM) Process

• G. Chryssolouris (1), J. Kechagias, P. Moustakas, E. Koutras

Abstract
• This paper investigates experimentally the influence of different variables of
the Laminated Object Manufacturing (LOM) process on the tensile strength
of parts produced by LOM.
• The process variable tested were
• Layer Thickness (LT),
• Heater Temperature (HT),
• Platform Retract (PR),
• Heater Speed (HS),
• Laser Speed (LS),
• Feeder Speed (FS) and
• Platform Speed (PS).
• A typical test part has been used. Based on the statistical analysis of the
experimental results it was found that the tensile strength of a part produced
by LOM depends mainly on the Layer Thickness.
Process introduction
Variable introduction
Specimen collection
EXPERIMENTAL RESULTS
Results of specimen

Layer Thickness (LT),

Heater Temperature (HT),
Platform Retract (PR),
Heater Speed (HS),
Laser Speed (LS),
Feeder Speed (FS) and
Platform Speed (PS).
Statistical investigation of data