The document outlines the objectives and outcomes of an additive manufacturing course, detailing fundamental concepts, various additive manufacturing processes, and their applications in different fields. It covers extensive course syllabus units, including rapid prototyping systems and techniques, data formats, and applications ranging from engineering to biomedical fields. Additional sections focus on the historical development of prototyping, the roles of prototypes in product development, and a classification of prototype types.

1. ME711PE:
ADDITIVE MANUFACTURING

2. Course Objectives
1. To understand the fundamental concepts of
Additive Manufacturing (i.e. Rapid Prototyping)
and 3-D printing, its advantages and limitations.
2. To classify various types of Additive Manufacturing
Processes and know their working principle,
advantages, limitations etc.
3. To have a holistic view of various applications of
these technologies in relevant fields such as
mechanical, Bio-medical, Aerospace, electronics
etc.

3. Course Outcomes:
1. Describe various CAD issues for 3D printing and rapid
prototyping and related operations for
STL model manipulation.
2. Formulate and solve typical problems on reverse engineering
for surface reconstruction from physical prototype models
through digitizing and spline-based surface fitting.
3. Formulate and solve typical problems on reverse engineering
for surface reconstruction from digitized mesh models
through topological modelling and subdivision surface
fitting.
4. Explain and summarize the principles and key characteristics
of additive manufacturing technologies and commonly used
3D printing and additive manufacturing systems.
5. Explain and summarize typical rapid tooling processes for
quick batch production of plastic and metal parts.

4. Syllabus
UNIT – I
Introduction: Prototyping fundamentals, Historical development,
Fundamentals of Rapid Prototyping , Advantages and Limitations of
Rapid Prototyping, Commonly used Terms, Classification of RP process,
Rapid Prototyping Process Chain: Fundamental Automated Processes.
UNIT – II
Liquid-based Rapid Prototyping Systems: Stereo lithography
Apparatus (SLA): Models and specifications, Process, working principle,
photopolymers, photo polymerization, Layering technology, laser and
laser scanning, Applications, Advantages and Disadvantages, Case
studies.
Solid ground curing (SGC): Models and specifications, Process, working
principle, Applications, Advantages and Disadvantages, Case studies
Solid-based Rapid Prototyping Systems: Laminated Object
Manufacturing (LOM): Models and specifications, Process, working
principle, Applications, Advantages and Disadvantages, Case studies.
Fused Deposition Modeling (FDM): Models and specifications, Process,
working principle, Applications, Advantages and Disadvantages, Case
studies.

5. UNIT – III
Powder Based Rapid Prototyping Systems: Selective
laser sintering (SLS): Models and specifications,
Process, working principle, Applications, Advantages
and Disadvantages, Case studies.
Three dimensional Printing (3DP): Models and
specifications, Process, working principle, Applications,
Advantages and Disadvantages, Case studies.
Rapid Tooling: Introduction to Rapid Tooling (RT),
Conventional Tooling Vs RT, Need for RT. Rapid
Tooling Classification;
Indirect Rapid Tooling Methods: Spray Metal
Deposition, RTV Epoxy Tools, Ceramic tools,
Investment Casting, Spin Casting, Die casting, Sand
Casting, 3D Keltool process.
Direct Rapid Tooling : Direct AIM, LOM Tools, DTM
Rapid tool Process, EOS Direct Tool Process and Direct
Metal Tooling using 3DP

6. UNIT – IV
Rapid Prototyping Data Formats: STL Format, STL File Problems,
Consequence of Building Valid and Invalid Tessellated Models, STL
file Repairs: Generic Solution, Other Translators, Newly Proposed
Formats. Rapid Prototyping Software’s: Features of various RP
software’s like Magics, Mimics, Solid View, View Expert, 3 D View,
Velocity 2, Rhino, STL View 3 Data Expert and 3 D doctor.
UNIT – V
RPApplications: Application - Material Relationship, Application in
Design, Application in Engineering, Analysis and Planning, Aerospace
Industry, Automotive Industry, Jewelry Industry, Coin Industry, GIS
application, Arts and Architecture.
RP Medical and Bioengineering Applications: Planning and
simulation of complex surgery, Customized Implants & Prosthesis,
Design and Production of Medical Devices, Forensic Science and
Anthropology, Visualization of Bio molecules.

7. TEXT BOOKS
1. Rapid prototyping; Principles and Applications /Chua
C.K., Leong K.F. and LIM C.S/World Scientific
Publications
2. Rapid Manufacturing /D.T. Pham and S.S.
Dimov/Springer
REFERENCE BOOKS
1. Terry Wohlers, Wholers Report 2000, Wohlers
Associates
2. Rapid Prototyping and Manufacturing
/PaulF.Jacobs/ASME

8. 3D = Three-Dimensional
3DP = Three-Dimensional Printing
ABS = Acrylonitrile Butadiene Styrene
AIM = ACES Injection Molding
BPM = Ballistic Particle Manufacturing
CAD = Computer-Aided Design
CAE = Computer-Aided Engineering
CAM = Computer-Aided Manufacturing
CBC = Chemically Bonded Ceramics
CD = Compact Disc
CIM = Computer-Integrated Manufacturing
CLI = Common Layer Interface
CMM = Coordinate Measuring Machine
CNC = Computer Numerical Control
CSG = Constructive Solid Geometry
CT = Computerized Tomography
DMD = Direct Metal Deposition
DMLS = Direct Metal Laser Sintering
DSP = Digital Signal Processor
DSPC = Direct Shell Production Casting
EBM = Electron Beam Melting
EDM = Electric Discharge Machining
FEM = Finite Element Method
GPS = Global Positioning System
HPGL = Hewlett-Packard Graphics Language
IGES = Initial Graphics Exchange Specification
LAN = Local Area Network
LCD = Liquid Crystal Display
LEAF = Layer Exchange ASCII Format
LED = Light Emitting Diode
LENS = Laser Engineered Net Shaping
LMT = Layer Manufacturing Technologies
LOM = Laminated Object Manufacturing
M-RPM = Multi-Functional RPM
MEM = Melted Extrusion Modeling
MJM = Multi-Jet Modeling System
MJS = Multiphase Jet Solidification
MRI = Magnetic Resonance Imaging
NASA = National Aeronautical and Space
Administration
NC = Numerical Control
FDM = Fused Deposition Modeling

9. PC = Personal Computer
PCB = Printed Circuit Board
PDA = Personal Digital Assistant
PLT = Paper Lamination Technology
RFP = Rapid Freeze Prototyping
RP = Rapid Prototyping
RPI = Rapid Prototyping Interface
RPM = Rapid Prototyping and Manufacturing
RPS = Rapid Prototyping Systems
RPT = Rapid Prototyping Technologies
RSP = Rapid Solidification Process
SAHP = Selective Adhesive and Hot Press
SCS = Solid Creation System
SFF = Solid Freeform Fabrication
SFM = Solid Freeform Manufacturing
SGC = Solid Ground Curing
SLA = StereoLithography Apparatus
SLC = StereoLithography Contour
SLS = Selective Laser Sintering
SSM = Slicing Solid Manufacturing
SOUP = Solid Object Ultraviolet-Laser Printing
STL = StereoLithography File
UV = Ultraviolet
3D = Three-Dimensional
3DP = Three-Dimensional Printing
ABS = Acrylonitrile Butadiene Styrene
AIM = ACES Injection Molding
BPM = Ballistic Particle Manufacturing
CAD = Computer-Aided Design
CAE = Computer-Aided Engineering
CAM = Computer-Aided Manufacturing
CBC = Chemically Bonded Ceramics
CD = Compact Disc
CIM = Computer-Integrated Manufacturing
CLI = Common Layer Interface
CMM = Coordinate Measuring Machine
CNC = Computer Numerical Control
CSG = Constructive Solid Geometry
CT = Computerized Tomography
DMD = Direct Metal Deposition
DMLS = Direct Metal Laser Sintering
DSP = Digital Signal Processor
DSPC = Direct Shell Production Casting
EBM = Electron Beam Melting
EDM = Electric Discharge Machining
FDM = Fused Deposition Modeling
FEA = Finite Element Analysis
FEM = Finite Element Method
GPS = Global Positioning System
HPGL = Hewlett-Packard Graphics Language

10. INTRODUCTION
1. The competition in the world market for manufactured products has
intensified tremendously in recent years.
2. To bring products to the market swiftly, many of the processes
involved in the design, test, manufacture and market of the products
have been squeezed, both in terms of time and material resources.
3. The efficient use of such valuable resources calls for new tools and
approaches in dealing with them, and many of these tools and
approaches have evolved.
4. They are mainly technology-driven, usually involving the computer.
This is mainly a result of the rapid development and advancement
in such technologies over the last few decades.
5. In product development , time pressure has been a major factor in
determining the direction of the development and success of new
methodologies and technologies for enhancing its performance.
6. These also have a direct impact on the age-old practice of
prototyping in the product development process.

11. Prototyping fundamentals
Definition of a Prototype:
1. A prototype is an important and vital part of the
product development process.
2. In any design practice, the word “prototype” is
often not far from the things that the designers
will be involved in.

12. Types of Prototypes
• The general definition of the prototype contains
three aspects of interests:
1. The implementation of the prototype; from the
entire product (or system) itself to its sub-
assemblies and components,
2. The form of the prototype; from a virtual
prototype to a physical prototype, and
3. The degree of the approximation of the prototype;
from a very rough representation to an exact
replication of the product.

13. 1. The implementation aspect of the prototype covers the range of
prototyping the complete product (or system) to prototyping part
of, or a sub-assembly or a component of the product.
2. It is usually implemented full-scale as well as being fully
functional.
3. One example of such prototype is one that is given to a group of
carefully selected people with special interest, often called a
focus group, to examine and identify outstanding problems
before the product is committed to its final design.
4. On the other hand, there are prototypes that are needed to
study or investigate special problems associated with one
component, sub-assemblies or simply a particular concept of
the product that requires close attention.
5. An example of such a prototype is a test platform that is used to
find the comfortable rest angles of an office chair that will
reduce the risk of spinal injuries after prolonged sitting on such a
chair.
6. Most of the time, sub-assemblies and components are tested in
conjunction with some kind of test rigs or experimental
platform.

14. 1. The second aspect of the form of the prototype takes into account how
the prototype is being implemented.
2. On one end, virtual prototypes that refers to prototypes that are non-
tangible, usually represented in some form other than physical, e.g.
mathematical model of a control system. Such prototypes are usually
studied and analyzed.
3. An example is the visualization of airflow over an aircraft wing to
ascertain lift and drag on the wing during supersonic flight.
4. Such prototype is often used when either the physical prototype is too
large and therefore takes too long to build, or the building of such a
prototype is expensive.
5. The main drawback of these kinds of prototypes is that they are based on
current understanding and thus they will not be able to predict any
unexpected phenomenon.
6. It is very poor or totally unsuitable for solving unanticipated problems.
7. The physical model, on the other hand, is the tangible manifestation of
the product, usually built for testing and experimentation.
8. Examples of such prototypes include a mock-up of a cellular telephone
that looks and feels very much like the real product but without its
intended functions.
9. Such a prototype may be used purely for aesthetic and human factors
evaluation.

15. 1. The third aspect covers the degree of approximation or
representativeness of the prototype.
2. On one hand, the model can be a very rough representation of the
intended product, like a foam model, used primarily to study the
general form and enveloping dimensions of the product in its initial
stage of development.
3. Some rough prototypes may not even look like the final product, but
are used to test and study certain problems of the product
development.
4. An example of this is the building of catches with different material
to find the right “clicking” sound for a cassette player door.
5. On the other hand, the prototype can be an exact full scale exact
replication of the product that models every aspects of the
product,
6. e.g. the pre-production prototype that is used not only to satisfy
customer needs evaluation but also addressing manufacturing
issues and concerns.
7. Such “exact” prototypes are especially important towards the end-
stage of the product development process.

17. 1. Figure shows the various kinds of prototypes placed over the
three aspects of describing the prototype.
2. Each of the three axes represents one aspect of the description
of the prototype.
3. Rapid prototyping typically falls in the range of a physical
prototype, usually are fairly accurate and can be implemented on
a component level or at a system level.
4. This is shown as the shaded volume shown in Figure.
5. The versatility and range of different prototypes, from complete
systems to individual components, that can be produced by RP at
varying degrees of approximation makes it an important tool for
prototyping in the product development process.
6. Adding the major advantage of speed in delivery, it has
become an important component in the prototyping arsenal not
to be ignored.

18. Roles of the Prototypes
The roles that prototypes play in the product development process are
several.
They include the following:
(1)Experimentation and learning
(2) Testing and proofing
(3) Communication and interaction
(4) Synthesis and integration
(5) Scheduling and markers

19. 1. To the product development team, prototypes can
be used to help the thinking, planning,
experimenting and learning processes while
designing the product.
2. Questions and doubts regarding certain issues of the
design can be addressed by building and studying
the prototype.
3. For example, in designing the appropriate elbow-
support of an office chair, several physical
prototypes of such elbow supports can be built to
learn about the “feel” of the elbow support when
performing typical tasks on the office chair.
4. Prototypes can also be used for testing and
proofing of ideas and concepts relating to the
development of the product.
5. For example, in the early design of folding reading
glasses for the elderly, concepts and ideas of folding
mechanism can be tested by building rough physical
prototypes to test and prove these ideas to see if
they work as intended.

20. 1. The prototype also serves the purpose of communicating
information and demonstrating ideas, not just within the
product development team, but also to management and
client (whether in-house or external).
2. Nothing is clearer for explanation or communication of an
idea than a physical prototype where the intended audience
can have the full experience of the visual and tactile feel of
the product.
3. A three-dimensional representation is often more
superior than that of a two-dimensional sketch of the
product.
4. For example, a physical prototype of a cellular phone can be
presented to carefully selected customers.
5. Customers can handle and experiment with the phone
and give feedback to the development team on the
features of and interactions with the phone, thus
providing valuable information for the team to improve
its design.

21. 1. A prototype can also be used to synthesize the entire
product concept by bringing the various components
and sub-assemblies together to ensure that they will
work together.
2. This will greatly help in the integration of the product
and surface any problems that are related to putting
the product together.
3. An example is a complete or comprehensive
functional prototype of personal digital assistant
(PDA).
4. When putting the prototype together, all aspects of
the design, including manufacturing and assembly
issues will have to be addressed, thus enabling the
different functional members of the product
development team to understand the various
problems associated with putting the product
together.

22. 1. Prototyping also serves to help in the scheduling of the product
development process and is usually used as markers for the end or
start of the various phases of the development effort.
2. Each prototype usually marks a completion of a particular
development phase, and with proper planning, the development
schedule can be enforced.
3. Typically in many companies, the continuation of a development
project often hinges on the success of the prototypes to provide
impetus to management to forge ahead with it.
4. It should be noted that in many companies, prototypes do not
necessary serve all these roles concurrently, but they are certainly a
necessity in any product development project.
5. The prototypes created with Rapid Prototyping technologies will serve
most if not all of these roles.
6. Being accurate physical prototypes that can be built with speed,
many of these roles can be accomplished quickly and effectively,
and together with other productivity tools, e.g. CAD, repeatedly
with precision.

23. HISTORICAL DEVELOPMENT
1. The development of Rapid Prototyping is closely tied in with the
development of applications of computers in the industry.
2. The declining cost of computers, especially of personal and mini
computers, has changed the way a factory works.
3. The increase in the use of computers has spurred the
advancement in many computer-related areas including
Computer-Aided Design (CAD), Computer-Aided Manufacturing
(CAM) and Computer Numerical Control (CNC) machine tools.
4. In particular, the emergence of RP systems could not have been
possible without the existence of CAD.
5. However, from careful examinations of the numerous RP systems
in existence today, it can be easily deduced that other than CAD,
many other technologies and advancements in other fields such as
manufacturing systems and materials have also been crucial in the
development of RP systems.
6. Table traces the historical development of relevant technologies
related to RP from the estimated date of inception.

25. 1. Prototyping or model making in the traditional sense is an age-
old practice.
2. The intention of having a physical prototype is to realize the
conceptualization of a design.
3. Thus, a prototype is usually required before the start of the full
production of the product.
4. The fabrication of prototypes is experimented in many forms —
material removal, castings, moulds, joining with adhesives etc.
and with many material types — aluminum, zinc, urethanes,
wood, etc.
5. Prototyping processes have gone through three phases of
development, the last two of which have emerged only in the
last 20 years .
6. Like the modeling process in computer graphics , the
prototyping of physical models is growing through its third
phase.
7. Parallels between the computer modeling process and
prototyping process can be drawn as seen in Table.
The three phases are described as follows.

26. First Phase: Manual Prototyping
1. Prototyping had began as early as humans began to
develop tools to help them live.
2. However, prototyping as applied to products in what is
considered to be the first phase of prototype
development began several centuries ago.
3. In this early phase, prototypes typically are not very
sophisticated and fabrication of prototypes takes on
average about four weeks, depending on the level of
complexity and representativeness.
4. The techniques used in making these prototypes tend to
be craft-based and are usually extremely labor intensive.

28. Second Phase: Soft or Virtual Prototyping
1. As application of CAD/CAE/CAM become more widespread, the early
1980s saw the evolution of the second phase of prototyping — Soft or
Virtual Prototyping.
2. Virtual prototyping takes on a new meaning as more computer tools
become available — computer models can now be stressed, tested,
analyzed and modified as if they were physical prototypes.
3. For example, analysis of stress and strain can be accurately predicted on the
product because of the ability to specify exact material attributes and
properties.
4. With such tools on the computer, several iterations of designs can be easily
carried out by changing the parameters of the computer models.
5. Also, products and as such prototypes tend to become relatively more
complex — about twice the complexity as before.
6. Correspondingly, the time required to make the physical model tends
to increase tremendously to about that of 16 weeks as building of
physical prototypes is still dependent on craft-based methods though
introduction of better precision machines like CNC machines helps.

29. 1. Even with the advent of Rapid Prototyping in the third phase, there is
still strong support for virtual prototyping.
2. These include material limitations (either because of expense or
through the use of materials dissimilar to that of the intended
part), the inability to perform endless what-if scenarios and the
likelihood that little or no reliable data can be gathered from the
rapid prototype to perform finite element analysis (FEA).
3. Specifically in the application of kinematic/dynamic analysis, he
described a program which can assign physical properties of many
different materials, such as steel, ice, plastic, clay or any custom
material imaginable and perform kinematics and motion analysis as if
a working prototype existed.
4. Despite such strengths of virtual prototyping, there is one
inherent weakness that such soft prototypes cannot be tested for
phenomena that is not anticipated or accounted for in the
computer program.
5. As such there is no guarantee that the virtual prototype is really
problem free

30. Third Phase: Rapid Prototyping
1. Rapid Prototyping of physical parts, or otherwise known as
solid freeform fabrication or desktop manufacturing or layer
manufacturing technology, represents the third phase in the
evolution of prototyping.
2. The invention of this series of rapid prototyping
methodologies is described as a “watershed event”
because of the tremendous time savings, especially for
complicated models.
3. Though the parts (individual components) are relatively three
times as complex as parts made in 1970s, the time required to
make such a part now averages only three weeks .
4. Since 1988, more than twenty different rapid prototyping
techniques have emerged.

31. FUNDAMENTALS OF RAPID PROTOTYPING
Common to all the different techniques of RP is the basic approach
they adopt, which can be described as follows:
(1) A model or component is modeled on a Computer-Aided Design/
Computer-Aided Manufacturing (CAD/CAM) system.
(2) The model which represents the physical part to be built must
be represented as closed surfaces which unambiguously define
an enclosed volume.
(3) This means that the data must specify the inside, outside and
boundary of the model. This requirement will become redundant if
the modeling technique used is solid modeling.
(4) This is by virtue of the technique used, as a valid solid model will
automatically be an enclosed volume.
(5) This requirement ensures that all horizontal cross sections that are
essential to RP are closed curves to create the solid object.

32. 1. The solid or surface model to be built is next
converted into a format dubbed the “STL”
(STereoLithography) file format which originates
from 3D Systems.
2. The STL file format approximates the surfaces of
the model by polygons.
3. Highly curved surfaces must employ many
polygons, which means that STL files for curved
parts can be very large.
4. However, there are some rapid prototyping
systems which also accept IGES (Initial Graphics
Exchange Specifications) data, provided it is of the
correct “flavor”.

33. 1. A computer program analyzes a STL file that defines the
model to be fabricated and “slices” the model into cross
sections.
2. The cross sections are systematically recreated through the
solidification of either liquids or powders and then combined
to form a 3D model.
3. Another possibility is that the cross sections are already thin,
solid laminations and these thin laminations are glued together
with adhesives to form a 3D model.
4. Other similar methods may also be employed to build the
model.

34. 1. Fundamentally, the development of RP can be seen in four primary areas.
2. The Rapid Prototyping Wheel in Figure depicts these four key aspects of Rapid Prototyping.
3. They are: Input, Method, Material and Applications.

35. 1.Input
1. Input refers to the electronic information required to
describe the physical object with 3D data.
2. There are two possible starting points — a computer
model or a physical model.
3. The computer model created by a CAD system can be
either a surface model or a solid model.
4. On the other hand, 3D data from the physical model is
not at all straightforward.
5. It requires data acquisition through a method known
as reverse engineering.
6. In reverse engineering, a wide range of equipment can
be used, such as CMM (coordinate measuring
machine) or a laser digitizer, to capture data points of
the physical model and “reconstruct” it in a CAD
system.

36. 2.Method
1. While they are currently more than 20 vendors for RP systems, the method
employed by each vendor can be generally classified into the following categories:
2. photo-curing, cutting and glueing/joining, melting and solidifying/fusing and
joining/binding.
3. Photo-curing can be further divided into categories of single laser beam,
double laser beams and masked lamp.
3.Material
1. The initial state of material can come in either solid, liquid or powder state.
2. In solid state, it can come in various forms such as pellets, wire or laminates.
3. The current range materials include paper, nylon, wax, resins, metals and ceramics
4.Applications
1. Most of the RP parts are finished or touched up before they are used for their
intended applications.
2. Applications can be grouped into (1) Design (2) Engineering, Analysis, and
Planning and (3) Tooling and Manufacturing.
3. A wide range of industries can benefit from RP and these include, but are not
limited to, aerospace, automotive, biomedical, consumer, electrical and electronics
products.

37. ADVANTAGES OF RAPID PROTOTYPING
1. Today’s automated, toolless, patternless RP systems can directly
produce functional parts in small production quantities.
2. Parts produced in this way usually have an accuracy and surface
finish inferior to those made by machining.
3. However, some advanced systems are able to produce near tooling
quality parts that are close to or are the final shape.
4. The parts produced, with appropriate post processing, will have
material qualities and properties close to the final product.
5. More fundamentally, the time to produce any part — once the design
data are available — will be fast, and can be in a matter of hours.
6. The benefits of RP systems are immense and can be categorized
into direct and indirect benefits

38. Direct and indirect benefits
1. The benefits to the company using RP systems are many.
2. One would be the ability to experiment with physical objects of any complexity
in a relatively short period of time.
3. It is observed that over the last 25 years, products realized to the market place
have increased in complexity in shape and form.
4. For instance, compare the aesthetically beautiful car body of today with
that of the 1970s. On a relative complexity scale of 1 to 3 as seen in Figure ,
it is noted that from a base of 1 in 1970, this relative complexity index has
increased to about 2 in 1980 and close to 3 in the 1990s.
5. More interestingly and ironically, the relative project completion times have not
been drastically increased.
6. Initially, from a base of about 4 weeks’ project completion time in 1970, it
increased to 16 weeks in 1980.
7. However, with the use of CAD/CAM and CNC technologies, project
completion time reduces to 8 weeks.
8. Eventually, RP systems allowed the project manager to further cut the
completion time to 3 weeks in 1995

40. 1. To the individual in the company, the benefits can be
varied and have different impacts.
2. It depends on the role in which they play in the
company.
3. The full production of any product encompasses a
wide spectrum of activities.
4. Kochan and Chua describe the impact of RP
technologies on the entire spectrum of product
development and process realization.
5. In Figure , the activities required for full production in
a conventional model are depicted at the top.
6. At the bottom of Figure is the RP model. Depending
on the size of production, savings on time and cost
could range from 50% up to 90%!

42. Benefits to Product Designers
1. The product designers can increase part complexity with little significant effects
on lead time and cost.
2. More organic, sculptured shapes for functional or aesthetic reasons can be
accommodated.
3. They can optimize part design to meet customer requirements, with little
restrictions by manufacturing.
4. In addition, they can reduce parts count by combining features in single-piece
parts that are previously made from several because of poor tool accessibility or
the need to minimize machining and waste.
5. With fewer parts, time spent on tolerance analysis, selecting fasteners, detailing
screw holes and assembly drawings is greatly reduced.
6. There will also be fewer constraints in the form of parts design without regard to
draft angles, parting lines or other such constraints.
7. Parts which cannot easily be set up for machining, or have accurate, large thin
walls, or do not use stock shapes to minimize machining and waste can now be
designed.
8. They can minimize material and optimize strength/weight ratios without regard
to the cost of machining.
9. Finally, they can minimize time-consuming discussions and evaluations of
manufacturing possibilities.

43. Benefits to the Tooling and Manufacturing Engineer
1. The main savings are in costs.
2. The manufacturing engineer can minimize design, manufacturing and
verification of tooling.
3. He can realize profits earlier on new products, since fixed costs are lower.
4. He can also reduce parts count and, therefore, assembly, purchasing
and inventory expenses.
5. The manufacturer can reduce the labor content of manufacturing,
since part-specific setting up and programming are eliminated,
machining/casting labor is reduced, and inspection and assembly are
also consequently reduced as well.
6. Reducing material waste, waste disposal costs, material transportation
costs, inventory cost for raw stock and finished parts (making only as
many as required, therefore, reducing storage requirements) can
contribute to low overheads.
7. Less inventory is scrapped because of design changes or disappointing
sales.

44. Indirect Benefits
1. Outside the design and production departments, indirect benefits can also be
derived.
2. Marketing as well as the customers will also benefit from the utilization of RP
technologies.
3.Benefits to Marketing
To the market, it presents new capabilities and opportunities.
It can greatly reduce time-to-market, resulting in
(1) reduced risk as there is no need to project customer needs and market dynamics
several years into the future,
(2) products which fit customer needs much more closely,
(3) products offering the price/performance of the latest technology,
(4) new products being test-marketed economically.
• Marketing can also change production capacity according to market demand,
possibly in real time and with little impact on manufacturing.
• One can increase the diversity of product offerings and pursue market niches
currently too small to justify due to tooling cost (including custom and semi-
custom production).
• One can easily expand distribution and quickly enter foreign markets.

45. Benefits to the Consumer
1. The consumer can buy products which meet more
closely individual needs and wants.
2. Firstly, there is a much wider diversity of offerings to
choose from.
3. Secondly, one can buy (and even contribute to the
design of) affordable products built-to-order.
4. Furthermore, the consumer can buy products at
lower prices, since the manufacturers’ savings will
ultimately be passed on.

46. CLASSIFICATION OF RAPID PROTOTYPING SYSTEMS
1. While there are many ways in which one can classify the numerous RP systems in
the market, one of the better ways is to classify RP systems broadly by the initial
form of its material, i.e. the material that the prototype or part is built with.
2. In this manner, all RP systems can be easily categorized into
3. (1) liquid-based (2) solid-based and (3) powder based.

47. Liquid-Based
1. Liquid-based RP systems have the initial form of its material in liquid state.
2. Through a process commonly known as curing, the liquid is converted into the
solid state.
3. The following RP systems fall into this category:
(1) 3D Systems’ Stereolithography Apparatus (SLA)
(2) Cubital’s Solid Ground Curing (SGC)
(3) Sony’s Solid Creation System (SCS)
(4) CMET’s Solid Object Ultraviolet-Laser Printer (SOUP)
(5) Autostrade’s E-Darts
(6) Teijin Seiki’s Soliform System
(7) Meiko’s Rapid Prototyping System for the Jewelry Industry
(8) Denken’s SLP
(9) Mitsui’s COLAMM
(10) Fockele & Schwarze’s LMS
(11) Light Sculpting
(12) Aaroflex
(13) Rapid Freeze
(14) Two Laser Beams
(15) Micro fabrication

48. 1. As is illustrated in the RP Wheel in Figure, three methods are possible under the
“Photo-curing” method.
2. The single laser beam method is most widely used and include all the above RP systems
with the exception of (2), (11), (13) and (14).
3. Cubital (2) and Light Sculpting (11) use the masked lamp method, while the two laser
beam method is still not commercialized.
4. Rapid Freeze (13) involves the freezing of water droplets and deposit in a manner
much like FDM to create the prototype.

49. Solid-Based
1. Except for powder, solid-based RP systems are meant to encompass all forms of
material in the solid state.
2. In this context, the solid form can include the shape in the form of a wire, a roll,
laminates and pellets.
The following RP systems fall into this definition:
(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) Solidscape’s ModelMaker and PatternMaster
(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
(8) Ennex Corporation’s Offset Fabbers

50. • Referring to the RP Wheel in Figure , two methods are possible for solid-based RP
systems.
• RP systems (1), (3), (4) and (9) belong to the Cutting and Glueing/Joining method,
while the Melting and Solidifying/Fusing method used RP systems (2), (5), (6), (7)
and (8).

51. Powder-Based
• In a strict sense, powder is by-and-large in the solid state.
• However, it is intentionally created as a category outside the solid-based RP
systems to mean powder in grain-like form.
• The following RP systems fall into this definition:
(1) 3D Systems’s Selective Laser Sintering (SLS)
(2) EOS’s EOSINT Systems
(3) Z Corporation’s Three-Dimensional Printing (3DP)
(4) Optomec’s Laser Engineered Net Shaping (LENS)
(5) Soligen’s Direct Shell Production Casting (DSPC)
(6) Fraunhofer’s Multiphase Jet Solidification (MJS)
(7) Acram’s Electron Beam Melting (EBM)
(8) Aeromet Corporation’s Lasform Technology
(9) Precision Optical Manufacturing’s Direct Metal Deposition (DMDTM)
(10) Generis’ RP Systems (GS)
(11) Therics Inc.’s Theriform Technology
(12) Extrude Hone’s Prometal TM 3D Printing Process

52. 1. All the above RP systems employ the Joining/Binding
method.
2. The method of joining/binding differs for the above
systems in that some employ a laser while others use a
binder/glue to achieve the joining effect.

53. RAPID PROTOTYPING PROCESS CHAIN

54. RAPID PROTOTYPING PROCESS CHAIN
1.FUNDAMENTAL AUTOMATED PROCESSES
1. There are three fundamental fabrication processes as shown in Figure.
2. They are Subtractive, Additive and Formative processes.
3. In the subtractive process, one starts with a single block of solid material larger
than the final size of the desired object and material is removed until the
desired shape is reached.
4. In contrast, an additive process is the exact reverse in that the end product is
much larger than the material when it started.
5. A material is manipulated so that successive portions of it combine to form the
desired object.
6. Lastly, the formative process is one where mechanical forces or restricting forms
are applied on a material so as to form it into the desired shape.
7. There are many examples for each of these fundamental fabrication processes.
Subtractive fabrication processes include most forms of machining processes —
CNC or otherwise.
8. These include milling, turning, drilling, planning, sawing, grinding, EDM, laser
cutting, water-jet cutting and the likes

56. 1. Most forms of rapid prototyping processes such as
Stereolithography and Selective Laser Sintering fall
into the additive fabrication processes category.
2. Examples of formative fabrication processes are:
Bending, forging, electromagnetic forming and plastic
injection molding.
3. These include both bending of sheet materials and
molding of molten or curable liquids.
4. The examples given are not exhaustive but indicative
of the range of processes.
5. Hybrid machines combining two or more fabrication
processes are also possible. For example, in
progressive pressworking, it is common to see a
hybrid of subtractive (as in blanking or punching) and
formative (as in bending and forming) processes.

57. 2.PROCESS CHAIN
1. All RP techniques adopt the same basic approach.
2. As such all RP systems generally have a similar sort of process chain. Such a
generalized process chain is shown in Figure.
3. There are a total of five steps in the chain and these are 3D modeling, data
conversion and transmission, checking and preparing, building and post
processing.

58. 1. Depending on the quality of the model and part in Steps 3 and 5
respectively, the process may be iterated until a satisfactory
model or part is achieved.
2. However, like other fabrication processes, process planning is
important before the RP commences.
3. In process planning, the steps of the RP process chain are listed.
4. The first step is 3D geometric modeling.
5. In this instance, the requirement would be a workstation and a
CAD modeling system.
6. The various factors and parameters which influence the
performance of each operation are examined and decided upon.
7. For example, if a SLA is used to build the part, the orientation of
the part is an important factor which would, amongst other
things, influence the quality of the part and the speed of the
process.
8. Needless to say, an operation sheet used in this manner requires
proper documentation and guidelines.
9. Good documentation, such as a process logbook, allows future
examination and evaluation, and subsequent improvements can
be implemented to process planning.

59. 3.3D MODELING
1. Advanced 3D CAD modeling is a general prerequisite in RP processes and,
usually is the most time-consuming part of the entire process chain.
2. It is most important that such 3D geometric models can be shared by the
entire design team for many different purposes, such as interference
studies, stress analyses, FEM analysis, detail design and drafting, planning
for manufacturing, including NC programming, etc.
3. Many CAD/CAM systems now have a 3D geometrical modeler facility with
these special purpose modules.
4. There are two common misconceptions amongst new users of RP.
5. First, unlike NC programming, RP requires a closed volume of the model,
whether the basic elements are surfaces or solids.
6. This confusion arises because new users are usually acquainted with the use
of NC programming where a single surface or even a line element can be an
NC element.
7. Second, new users also usually assume what you see is what you get. These
two misconceptions often lead to under specifying parameters to the RP
systems, resulting in poor performance and non optimal utilization of the
system.

60. 1. Examples of considerations that have to be taken
into account include orientation of part, need for
supports, difficult-to-build part structure such as thin
walls, small slots or holes and overhanging elements.
2. Therefore, RP users have to learn and gain experience
from working on the system.
3. The problem is usually more complex than one can
imagine because there are many different RP
machines which have different requirements and
capabilities.
4. For example, while a SLA requires supports, SGC does
not, and SGC works most economically if many parts
are nested together and processed simultaneously.

61. 4.DATA CONVERSION AND TRANSMISSION
1. The solid or surface model to be built is next converted into a format dubbed the
STL file format.
2. This format originates from 3D Systems which pioneers the STereoLithography
system.
3. The STL file format approximates the surfaces of the model using tiny triangles.
4. Highly curved surfaces must employ many more triangles, which mean that STL
files for curved parts can be very large.
5. Almost, if not all, major CAD/CAM vendors supply the CAD-STL interface.
6. Since 1990, almost all major CAD/CAM vendors have developed and integrated
this interface into their systems.
7. This conversion step is probably the simplest and shortest of the entire process
chain.
8. However, for a highly complex model coupled with an extremely low performance
workstation or PC, the conversion can take several hours.
9. Otherwise, the conversion to STL file should take only several minutes.
10. Where necessary, supports are also converted to a separate STL file.
11. Supports can alternatively be created or modified in the next step by third party
software which allows verification and modifications of models and supports.

62. 1. The transmission step is also fairly straightforward.
2. The purpose of this step is to transfer the STL files
which reside in the workstation to the RP system’s
computer.
3. It is typical that the workstation and the RP system are
situated in different locations.
4. The workstation, being a design tool, is typically located
in a design office.
5. The RP system, on the other hand, is a process or production
machine, and is usually located on the shopfloor.
6. 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).
7. No validation of the quality of the STL files is carried out at
this stage.

63. 5. CHECKING AND PREPARING
• The computer term, garbage in garbage out, is also applicable to RP.
• Many first time users are frustrated at this step to discover that their STL files are
faulty.
• However, more often than not, it is due to both the errors of CAD models and
the non robustness of the CAD-STL interface.
• Unfortunately, today’s CAD models — whose quality are dependent on the CAD
systems, human operators and postprocesses — are still afflicted with a wide
spectrum of problems, including the generation of unwanted shell-punctures (i.e.
holes, gaps, cracks, etc.).
• These problems, if not rectified, will result in the frequent failure of
applications downstream.
• At present, the CAD model errors are corrected by human operators assisted by
specialized software such as MAGICS, a software developed by Materialise, N.V.,
Belgium.
• 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.

64. • Once the STL files are verified to be error-free, the RP system’s
computer analyzes the STL files that define the model to be fabricated
and slices the model into cross-sections.
• The cross-sections are systematically recreated through the
solidification of liquids or binding of powders, or fusing of solids, to
form a 3D model. In a SLA, for example, each output file is sliced
into cross-sections, between 0.12 mm (minimum) to 0.50 mm
(maximum) in thickness.
• Generally, the model is sliced into the thinnest layer (approximately
0.12 mm) as they have to be very accurate.
• The supports can be created using coarser settings.
• An internal cross hatch structure is generated between the inner and
the outer surface boundaries of the part.
• This serves to hold up the walls and entrap liquid that is later
solidified with the presence of UV light.

65. • Preparing building parameters for positioning and
stepwise manufacturing in the light of many available
possibilities can be difficult if not accompanied by
proper documentation.
• These possibilities include determination of the
geometrical objects, the building orientation, spatial
assortments, arrangement with other parts, necessary
support structures and slice parameters.
• They also include the determination of technological
parameters such as cure depth, laser power and other
physical parameters as in the case of SLA.
• It means that user-friendly software for ease of use and
handling, user support in terms of user manuals,
dialogue mode and online graphical aids will be very
helpful to users of the RP system.

66. 1. Many vendors are continually working to improve their systems in this
aspect.
2. For example, a software, Partman Program, was introduced by 3D Systems
to reduce the time spent on setting parameters for the SLA process.
3. Before this software is introduced, parameters (such as the location in the
250 mm × 250 mm box and the various cure depths) had to be set manually.
4. This was very tedious for there may be up to 12 parameters to be keyed in.
5. These parameters are shown in Table 2.1.
6. However, the job is now made simpler with the introduction of default
values that can be altered to other specific values.
7. These values can be easily retrieved for use in other models.
8. This software also allows the user to orientate and move the model such
that the whole model is in the positive axis’ region (the SLA uses only
positive numbers for calculations).
9. Thus the original CAD design model can also be in “negative” regions
when converting to STL format.

68. 6.BUILDING
1. For most RP systems, this step is fully automated.
Thus, it is usual for operators to leave the machine
on to build a part overnight.
2. The building process may take up to several hours
to build depending on the size and number of
parts required.
3. 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.

69. 7.POSTPROCESSING
1. The final task in the process chain is the post processing task.
2. At this stage, generally some manual operations are necessary.
3. As a result, the danger of damaging a part is particularly high.
4. Therefore, the operator for this last process step has a high responsibility for the
successful process realization.
5. He necessary post processing tasks for some major RP systems are shown in Table

70. 1. The cleaning task refers to the removal of excess
parts which may have remained on the part.
2. 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.
3. Similarly, for SLS parts, the excess powder has to
be removed.
4. Likewise for LOM, pieces of excess woodlike blocks
of paper which acted as supports have to be
remove

71. 1. As shown in Table, the SLA procedures require the
highest number of post processing tasks.
2. More importantly, for safety reason, specific
recommendations for post processing tasks have to be
prepared, especially for cleaning of SLA parts.
3. It was reported that accuracy is related to the post-
treatment process.
4. Specifically, the swelling of SLA-built parts with the use
of cleaning solvents.
5. Parts are typically cleaned with solvent to remove un
reacted photosensitive resin.
6. Depending upon the “build style” and the extent of
cross linking in the resin, the part can be distorted
during the cleaning process.
7. This effect was particularly pronounced with the more
open “build styles” and aggressive solvents.

72. 1. With the “build styles” approaching a solid fill and more
solvent-resistant materials, damage with the cleaning
solvent can be minimized.
2. With newer cleaning solvents, like TPM (tripropylene glycol
monomethyl ether) introduced by 3D Systems, part damage
due to the cleaning solvent can be reduced or even
eliminated .
3. SLA parts are built with pockets of liquid embedded within
the part.
4. Therefore, postcuring is required.
5. All other nonliquid RP methods do not undergo this task.
6. Finishing refers to secondary processes such as sanding and
painting used primarily to improve the surface finish or
aesthetic appearance of the part.
7. It also includes additional machining processes such as
drilling, tapping and milling to add necessary features to the
parts.

73. 1. What are the three types of automated fabricators? Describe them
and give two examples each.
2. Describe the five steps involved in a general RP process chain.
Which steps do you think are likely to be iterated?
3. After 3D geometric modeling, a user can either make a part
through NC programming or through rapid prototyping. What are
the basic differences between NC programming and RP in terms
of the CAD model?
4. STL files are problematic. Is this a fair statement to make?
Discuss.
5. Preparing for building appears to be fairly sophisticated. In the
case of a SLA, what are some of the considerations and
parameters involved?
6. Distinguish cleaning, postcuring and finishing which are the
various tasks of postprocessing. Name two RP processes that do
not require postcuring and one that does not require cleaning.
7. Which step in the entire process chain is, in your opinion, the
shortest? Most tedious? Most automated? Support your choice.

74. THANK YOU
BOSHALLA NARSAIAH