Rapid prototyping technologies,applications &part deposition planning 2

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RAPID PROTOTYPING TECHNOLOGIES,APPLICATIONS &PART DEPOSITION PLANNING

Johnbin johnson

S7 ME

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CONTENT• HISTORY• INTRODUCTION• PRINCIPLE & FLOWCHART• WHY RAPID PROTOTYPING?• RP PROCESSES STEREOLITHOGRAPHY

FUSED DEPOSITION MODELING

LAMINATED OBJECT MANUFACTURING

SELECTIVE LASER SINTERING

• PART DEPOSITION PLANNING

ACCURACY OF RP PARTS

PART DEPOSITION ORIENTATION

• LIMITATIONS• APPLICATIONS

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HISTORY

• First phase-Manual prototyping by skilled craftsman (old practice)

• Second phase-soft prototype modeled by 3D Curves & surfaces (mid 1970)

• Third phase-rapid prototyping (1980)

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INTRODUCTION

• PROTOTYPE A prototype is a model used to test and evaluate a design .it is

just a test version of an experiment or machine .Before the start

of full production a prototype is usually fabricated & tested.

• RAPID PROTOTYPING Rapid Prototyping (RP) can be defined as a group of techniques

used to quickly fabricate a scale model of a part or assembly

using three-dimensional computer aided design (CAD) data.

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PRINCIPLE & FLOW CHART

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PRINCIPLE & FLOW CHART (con..)

• First process in RP is generation of 3D model of the product .Commonly used 3D CAD systems for this are

o Pro/Eo UGo CATIAo IDEAS

• Second process is tessellation of 3D model .Basically it is

generation of layer model .A STL file is created after tessellation

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PRINCIPLE & FLOW CHART (con..)

• In next process slicing of model is done by various slicing softwares like

MeshLab

openRP

Admesh

• Generated sliced data is stored in standard data formats like SLC or CLI.

• The next stage of process is making of physical model in which we use a RP system software.

• RP system software generates laser scanning path in which material deposition should occur.

PRINCIPLE & FLOW CHART (con..)

• Final stage is post processing or finishing of part in which following process will occur

o Cleaningo Polishingo Paintingo Milling ,grinding etc..

Prototype is then tested &suggested changes are once again incorporated during the solid modeling stage.

TESSELLATION & SLICING

• Surfaces of CAD model are piecewise approximated by a series of triangles.

TESSELLATION & SLICING

• In slicing the CAD model is divided into number of layers .slice thickness is important thing we should consider during this stage.

Why Rapid Prototyping?

• The Prototype gives the user a fair idea about the final look of

the product.

• To increase effective communication between user & designer.

• Decrease development time.

• Increasing number of variants of products.

• It is easier to find the design flaws in the early developmental

stages.

• cost effective.

• can produce complex products.

PROCESSES• One method of classification of RP process is based on state of

aggregation of their original material.

STEREOLITHOGRAPHY

• In this process liquid resin which forms a solid polymer is exposed to UV rays.

• Main parts of SL machine is a build platform (mounted on vat) & argon ion laser or UV Helium-cadmium laser.

• Laser scans first layer & platform is then lowered equal to one slice thickness.

• A dip-delay is provided for the liquid polymer to settle to a flat & even surface.

• Scanning speeds ~ 500 to 2500 mm/s.

• Once complete part is deposited ,it is removed from vat & excess resin is drained.

STEREOLITHOGRAPHY (con)

stereolithography

STEREOLITHOGRAPHY (con)

A part produced by sterelithography

SL machine

FUSED DEPOSITION MODELING

• Main part of a FDM is a movable (x-y) nozzle.

• Molten polymeric material comes through this nozzle which

gets deposited on the substrate.

• Workhead is controlled in the x-y plane during each layer.

• Build material is heated slightly above its melting point so it

can solidifies easily.

• One layer will cold welds to previous layer.

• Part is fabricated from the base up, using a layer-by-layer

procedure.

FUSED DEPOSITION MODELING

(con..)

Fused Deposition Modeling

LAMINATED OBJECT MANUFACTURING

• Profiles of object cross section are cut from paper or another material by using laser.

• Power full CO2 Laser is used for this purpose.

• Paper is unwound from feed roll.

• It is bonded to previous layer with use of a heated roller.

• Heated roller activates a heat sensitive adhesive .

• Slices are cut by laser.

• Waste paper is wound on a take up roll.

• Once one slice is completed platform is lowered & same process is repeated.

LAMINATED OBJECT MANUFACTURING

LOM process

SELECTIVE LASER SINTERING

• In SLS same process as that in LOM is used.

• But in SLS fine polymeric powder like polycarbonate is used.

• Powder is spread over substrate using a power feed roller.

• CO2 laser beam sinters heat‑fusible powders.

• Grains having direct contact with laser beam fuse with

previous layer.

• Then bed is lowered & In areas not sintered, the powders are

loose and can be poured out of completed part

SELECTIVE LASER SINTERING

SLS process

PART DEPOSITION PLANNING• It is very important because it decides

• part accuracy• surface quality• building time• cost of part

• Accuracy of a part depends upon tessellation & slicing.• Tessellation errors can be reduced by reducing size of triangles.• Slicing of CAD model with a very small slice thickness leads to

large build time .• At the same time if large slice thickness is chosen, the surface finish

is very bad .• Slicing errors can be reduced by using adaptive slicing

PART DEPOSITION ORIENTATION

• Selection of suitable part deposition orientation can reduce

part building time ,cost etc..

• But it is difficult & time consuming because we should

consider various processes.

• A multi objective genetic algorithm is proposed for part

deposition planning.

LIMITATION

• Poor surface finish due to Staircase appearance caused due to

layering .

• It may not be suitable for large sized applications.

• Limited strength.

• Some important developmental steps could be omitted to get a

quick and cheap working model. 

• Mechanical performance of the fabricated parts is limited by the

materials used in the RP process .

• Shrinkage and distortion of RP parts.

APPLICATION• Applications of rapid prototyping can be classified into three

categories:

1. Design .

2. Engineering analysis and planning .

3. Tooling and manufacturing.

• Designers are able to confirm their design by building a real physical model in minimum time using RP

• It will help them to visualize the object, Early detection of design errors , Reduced lead times etc..

• In Engineering analysis and planning we will be able to do stress analysis ,flow analysis ,mock-up etc..

APPLICATION

• In tooling application Pattern is created by RP and the pattern is used to fabricate the tool.

• RP is commonly used in industries like automotive ,aerospace, jewelry ,biomedical etc…

Thank you