steps required for reverse engineering process

1. 1. What is Rapid Prototyping
Rapid Prototyping: Traditional manufacturing:
additive material subtractive material

2. 1.1 Characteristics of RP
 A technology that produces models and
prototype parts from 3D CAD model data, CT
and MRI scan data, and model data created from
3D object digitizing systems
 RP systems join together liquid, powder and
sheet materials to form parts
Layer by layer, RP machines fabricate plastic,
wood, ceramic and metal objects
RP also known as Solid Freeform Fabrication (SFF)
or Layer Manufacturing (LM)

3. Build
Prototype
1.2 Basic process of RP
Three stages: pre-processing, building, and
post processing
RP Process Post Process
Pre Process
Generate
.STL file
Build Supports
if needed
Slicing
Remove
Supports
Clean Surface
Post Cure if needed
Part Completed
CAD Model
Surface/Solid
Model
in RP
systems
in CAD

4. 1.3 Benefits of RP
Shorten time to market &
reduced development cost
THE COST OF CHANGE
PHASE COST
Conceptual modeling $10
Detail design $100
Prototype/test $1,000
Manufacturing $10,000
Product release $100,000
Source: Wohlers Associates
3D visualization of product
designs
Esure that customers have
a clear understanding
“A picture is worth a
thousand words; a model is
worth a thousand pictures.”
Improved product quality
RP enable more design
iterations in a given time

5. 2. Common types of RP
 The first RP system was introduced in 1988
 Common types of RP technologies now:
- StereoLithography (SL)
- Fused Deposition Modeling (FDM)
- Selective Laser Sintering (SLS)
- Laminated Object Manufacturing (LOM)
- 3D Printing (3DP)

6. 2.1 Stereo-Lithography (SL)
1. The elevator lowered by 1
layer deep;
2. The Blade sweep across
the vat, apply an even layer
of resin on top of the part;
3. As the laser beam strikes
the resin surface, the liquid
resin is hardened to a solid
plastic;
4. Loop through the three
steps to cure a new layer.
Laser
Scanning
Mirror
Liquid Resin
Cured resin
to form model
Re-coating
Blade

7. Stereo-Lithography Apparatus (SLA)
 Representative:
from 3D Systems, Inc.
 Materials:
photocurable resins
 Adv. & Disadvantages:
 Good dimensional
accuracy
 Good surface finish
 Narrow range of
materials
 Relatively high cost
 Post curing
 Application areas:
- Prototypes for concept
models;
- Form-fit for assembly
tests and process
planning;
- Models for investment
casting, replacement of
the wax pattern;
- Patterns for metal
spraying, epoxy molding
and other soft tooling

8. 2.2 Fused Deposition Modeling (FDM)
1. Extrusion head and
elevator move to start
position;
2. The head extrude
layer of support;
3. The head extrude
layer of model;
4. Loop through the three
steps to build the next
layer.
Part
Heated extrusion
head
Model & Support Filaments
Elevator & Platform

9. Fused Deposition Modeling (FDM)
 Representative:
from Stratasys Inc.
 Materials:
thermoplastic material such
as wax, ABS plastic &
elastomer
 Adv. & Disadvantages:
 clean, simple, easy to operate
 A good variety of material
 Mid range performance/cost
 Relative low accuracy
 Poor strength in vertical
direction
- Slow for building a mass part
 Application areas:
- Conceptual modeling;
- Fit, form and functional
test;
- Pattern for investment
casting;
- The MABS (methy
methacrylate ABS)
material is particularly
suitable for medical
applications.

10. 2.3 Selective Laser Sintering (SLS)
1. Piston of the part built
chamber lower by one layer;
2. Piston of powder cartridges
raise up;
3. Roller spread powder
evenly over the built
surface;
4. Laser beam scan over the
top of the part, melting the
powder and fuse it to the
previous layer;
5. Loop through the four steps
to build the next layer.
Laser
Scanning
Mirror
Roller
Piston
Powder
cartridges
Build
Chamber

11. Selective Laser Sintering (SLS)
 Representative:
from DTM Corporation
 Materials:
powder material such as nylon,
wax, polycarbonate, metal,
ceramic, elastomer, etc.
Adv. & Disadvantages:
 Large variety of material available
 Produced in short time
 No additional support required
 No post curing required
 Heat up powder & cool down part
 Smoothness of surface restricted
 Expensive running cost
 Toxic gases generated
 Application areas:
- Visual representation;
- durable enough for most
functional tests;
- Pattern for making soft
tooling, casting;
- Direct manufacture of metal
mould;
- Small batch production run.

12. 2.4 Laminated Object Manufacturing
(LOM)
1. The sheet material is stretched
from the supply roller to the
take-up roller;
2. The heated laminated roller
passes over the sheet bonding
it to the previous layer;
3. Laser cuts the profile of that
layer and hatching the excess
material for later removal;
4. Loop through the three steps
to form a new layer.

13. Laminated Object Manufacturing (LOM)
 Representative:
from Helisys
 Materials:
sheet material such as paper,
plastic, ceramic, composite etc.
Adv. & Disadvantages:
 A relatively high speed process
 No post curing required
 No support structure required
 Simple to use
 The most commonly used
material is only paper
 Must be post processed
immediately
 Restricted to build complex
parts
 Fire hazard occasionally
happened
 Application areas:
- Visual representation;
- Concept modeling;
- Pattern for sand casting;

14. 2.5 3D Printing (3DP)
less costly and less capable
variation of RP technology
Companies install them in offices
near their CAD systems for concept
modeling.

15. 3. Application cases of RP
Common applications
of the RP technology:
 Design
concept models
 Marketing
models for tenders,
customer feedback,
presentations and
brochures
 Test & Analysis
functional testing;
strong models for wind
tunnel and stress
analysis
 Tooling
masters and patterns
for a broad range of
manufacturing
processes
 Medicine
artificial limbs, tools and
instruments

16. 4. Rapid Tooling Making (RTM)
 INDIRECT RPM: Pattern created by RP used to fabricate
tool
- RP-fabricated part as master in making silicon-rubber
mold (subsequently used as production mold)
- RP patterns to make sand molds for sand casting
- Fabrication of patterns of low-melting pt. materials for
Investment casting
 DIRECT RPM: RP used to make the tool itself
- 3D printing to create die geometry in metallic powders
(followed by sintering & infiltration)

17. 4. Rapid Tooling Making (RTM)
 low volume (from
tens to hundreds)
- Soft Tooling
 Intermediate (from
hundreds to
thousands)
- Metal filled Epoxy
Tooling
- Powdered Metal
Tooling
Aluminum-filled epoxy mold,
SL master, and molded
thermoplastic parts