RAPID PROTOTYPING

1. Types of Prototypes
2. Fundamentals of Rapid Prototyping
3. Rapid Prototyping Technologies
4. Applications and Benefits of Rapid Prototyping
 Roles of Prototypes
 Experimentation and learning
 Testing and Proofing
 Communication and interaction
 Synthesis and integration
 Scheduling and markers
 There Phases of Developing Leading to
RP
 Manual Prototyping
 Soft or Virtual Prototyping
 Rapid Prototyping
 Parallels between geometric modeling and
prototyping
Geometric Modeling Prototyping
 1 Phase : 2D wireframe  1 Phase : Manual Prototyping
 Started Phase 1960s  Traditional practice for many
 Few straight lines on year
displays may be  Prototyping as a skilled crafts
 Natural – drafting techiques is
 Traditional and manual
 Based on material of
prototypes
 Parallels between geometric modeling and
prototyping
Geometric Modeling Prototyping
 2 Phase : 3D curves  2 Phase : Soft or Virtual
 Mid 1970s Prototyping
 Increasing complexity  Mid 1970s
 Representation more  Increasing complexity
information about precise  Virtual prototype can be
shape, size and surface stressed, simulated and tested
contour of parts with exact mechanical
properties
 Parallels between geometric modeling and
prototyping
Geometric Modeling Prototyping
 3 Phase : Solid Modeling  3 Phase : Rapid Prototyping
 Early 1980s  Mid 1980s
 Edges, surfaces and holes  Benefit of a hard prototype
are knitted together to form made in a very short time.
a cohesive whole  Prototype can also assist in the
 No longer ambiguous but manufacturing of the products
exact
 Rapid Prototyping background
 In this age of fast growth (rapid technology age) the
customer demands faster delivery.
 Customer do not have time to wait. Therefore, one of the
modern business requirements is that the traditional
processing time needs to be shortened.
 Thus, in order to survive in this ‘Buyer’s market’
technological advancements are essential to meet the
buyer’s demand.
 In the quest for fast manufacturing, all non-productive
times need to be eliminated.
 The traditional method involves time loss on concept
designing, manufacturing, assembly and testing.
 E.g. in case of a foundry, lot of time is spent on pattern
designing, marketing, getting the casting done and then
evaluating its performance.
 This initially involves designing & re-designing, until
getting a satisfactory product, which a very slow process.
 Then, the natural questions are
- How to get this time recovered ?
- How to overcome this slow trend?
- Can one wait in this advanced technology age?

©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
 Rapid Prototyping (RP)
A family of fabrication processes developed to make
engineering prototypes in minimum lead time based on a
CAD model of the item
 Traditional method is machining
 Can require significant lead-times – several weeks,
depending on part complexity and difficulty in
ordering materials
 RP allows a part to be made in hours or days, given that a
computer model of the part has been generated on a CAD
system
 Rapid Prototyping
 Product designers want to have a physical model of a new
part or product design rather than just a computer model or
line drawing
 Creating a prototype is an integral step in design
 A virtual prototype (a CAD model of the part) may not
be sufficient for the designer to visualize the part
adequately
 Using RP to make the prototype, the designer can see and
feel the part and assess its merits and shortcomings
 Starting Materials in Material Addition RP
1. Liquid monomers that are cured layer by layer into solid
polymers
2. Powders that are aggregated and bonded layer by layer
3. Solid sheets that are laminated to create the solid part
Additional Methods
1. In addition to starting material, the various material addition RP
technologies use different methods of building and adding layers
to create the solid part
1. There is a correlation between starting material and part building
techniques
 Steps in RP Technology

 Creation of the CAD model of design

 Conversion of CAD model into STL format
 Slicing of STL file into thin sections
 Building part layer by layer
 Post processing/ finishing and the joining
processes.

©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
 Solid Model to Layers

Figure 34.1 Conversion of a solid model of an object into layers

(only one layer is shown).
 More About Rapid Prototyping
 Alternative names for RP:
 Layer manufacturing
 Direct CAD manufacturing
 Solid freeform fabrication
 Rapid prototyping and manufacturing (RPM)
 RP technologies are being used increasingly to make
production parts and production tooling, not just
prototypes
 Classification of RP Technologies
 There are various ways to classify the RP techniques that
have currently been developed
 The RP classification used here is based on the form of
the starting material:
1. Liquid-based
2. Solid-based
3. Powder-based
 RP Applications
 Applications of rapid prototyping can be classified into
three categories:
1. Design
2. Engineering analysis and planning
3. Tooling and manufacturing
 Design Applications
 Designers are able to confirm their design by building a
real physical model in minimum time using RP
 Design benefits of RP:
 Reduced lead times to produce prototypes
 Improved ability to visualize part geometry
 Early detection of design errors
 Increased capability to compute mass properties
 Engineering Analysis and Planning
 Existence of part allows certain engineering analysis and
planning activities to be accomplished that would be more
difficult without the physical entity
 Comparison of different shapes and styles to determine
aesthetic appeal
 Wind tunnel testing of streamline shapes
 Stress analysis of physical model
 Fabrication of pre-production parts for process
planning and tool design
 Tooling Applications
 Called rapid tool making (RTM) when RP is used to
fabricate production tooling
 Two approaches for tool-making:
1. Indirect RTM method
2. Direct RTM method
 Direct RTM Method
RP is used to make the tool itself
 Example:
 3DP to create a die of metal powders followed by
sintering and infiltration to complete the die
 Manufacturing Applications
 Small batches of plastic parts that could not be
economically molded by injection molding because of the
high mold cost
 Parts with intricate internal geometries that could not be
made using conventional technologies without assembly
 One-of-a-kind parts such as bone replacements that must
be made to correct size for each user
 Problems with Rapid Prototyping
 Part accuracy:
 Staircase appearance for a sloping part surface due to
layering
 Shrinkage and distortion of RP parts
 Limited variety of materials in RP
 Mechanical performance of the fabricated parts is
limited by the materials that must be used in the RP
process