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