1. 1. What is Rapid PrototypingWhat is Rapid Prototyping
Rapid Prototyping: Traditional manufacturing:
additive material subtractive material
1.1 1.1 Characteristics of RPCharacteristics 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
RPRP also known as Solid Freeform Fabrication (SFF) or Layer Manufacturing (LM)
BuildPrototype
1.2 1.2 Basic process of RPBasic process of RP
Three stages: pre-processing, building, and
post processing
RP Process Post ProcessPre Process
Generate.STL file
Build Supportsif needed
Slicing
RemoveSupports
Clean Surface
Post Cure if needed
Part Completed
CAD Model
Surface/SolidModel
in RPsystems
in CAD
1.3 1.3 Benefits of RPBenefits of RP
Shorten time to market & reduced development cost
THE COST OF CHANGE PHASE COST
Conceptual modeling $10Detail design $100Prototype/test $1,000Manufacturing $10,000Product release $100,000
Source: Wohlers Associates
3D visualization of product designsEsure 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
2. 2. Common types of RPCommon 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)
2.1 Stereo-Lithography (SL)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.
LaserScanningMirror
Liquid Resin
Sup
port
s
Cured resinto form model
Ele
vato
r &
Pl a
tfor
mRe-coatingBlade
Stereo-Lithography Apparatus (SLA)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
2.2 Fused Deposition Modeling (FDM)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.
S up p
o rt
Par
t
Heated extrusionhead
Model & Support Filaments
Elevator & Platform
Fused Deposition Modeling (FDM)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.
2.3 Selective Laser Sintering (SLS)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.
LaserScanningMirror
Roller
Piston
Par
t
Supp
ort
Powdercartridges
BuildChamber
Selective Laser Sintering (SLS)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.
2.4 Laminated Object Manufacturing2.4 Laminated Object Manufacturing (LOM) (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.
Laminated Object Manufacturing (LOM)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;
2.5 3D Printing (3DP) 2.5 3D Printing (3DP)
less costly and less capablevariation of RP technology
Companies install them in officesnear their CAD systems for concept modeling.
3. Application cases of RP3. 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
4. Rapid Tooling Making (RTM)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)
4. Rapid Tooling Making (RTM)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