RAPID PROTOTYPING

INTRODUCTION OF RAPID PROTOTYPING

• Is a revolutionary and powerful technology with wide range of application.• The process of prototyping involve quick

building up of a prototype or working model for the purpose of testing the various design features, ideas,concepts,funtionality,output and performance.

HISTORY OF RAPID PROTOTYPING

• In 60’s ,the first rapid prototyping technique became accessible in the later eighties and used for production of prototype and model parts.• In 70’s ,Herbert Voelcker, engineering

professor developed the basic tools of mathematics that clearly describe the three dimensional aspects and resulted in the earliest theories of algorithmic and mathematical theories for solid modeling.

• In 80’s, Carl Deckard ,researcher from the University of Texas. He pioneered the layer based manufacturing , he thought of building up the model layer by layer. He printed 3D models by utilizing laser light for fusing metal powder in solid prototypes,single layer at a time. Technique called ‘Selective Laser Sintering’.• Nowadays , the computer engineer has to simply

sketch the ideas on the computer screen with the help of a design program that is computer aided. Computer aided designing allows to make modification as required and can create a physical prototype that is a precise and proper 3D object.

THE ADVANTAGE OF RAPID PROTOTYPING

• CAD data files can be manufactured in hours.• Tool for visualization and concept verification.• Prototype used in subsequent manufacturing

operation to obtain final part.• Tooling for manufacturing operation can be

produce.

SUBTRACTIVE PROCESS

• Is the prevent process in the history of model making. Model makers once utilized materials like clay and wood or other hard material, to whittle, carve, or sculpt a model component. • The excess material was basically chiseled, cut,

and sanded to expose the design within the carving medium. • This process was understandably time intensive

and resulted in a finished product that was a one of a kind and could not be easily replicated without remaking the part from scratch.

ADDITIVE PROCESS• Is built by adding layers of material upon one

another.• This process are inhenrently different from

subtractive processes or consolidation processes. Example such as milling ,turning or drilling, use carefully planned tool movement to cut away material from a workpiece to form the desired part.• The part is constructed directly from a digital

3D model created through Computer Aided Design (CAD) software.

VIRTUAL PROCESS• To create each virtual cross section in then takes physical form

layer after until an identical prototype model is created.THE FUSED DEPOSITION MODELLING (FDM)

• Process constructs three-dimensional objects directly from 3D CAD data. A temperature controlled head extrudes thermoplastic material layer by layer.• This model is oriented and mathematically sliced into

horizontal layers varying from +/- 0.127 – 0.254mm thickness.• The system operates in X, Y and Z axes, drawing the

model one layer at a time.

STEREOLITHOGRAPHY• is an additive manufacturing process using a vat of

liquid UV curable photopolymer ‘resin’ and UV laser to build parts a layer at a time.• The laser beam traces a part cross section pattern

on the surface of the liquid resin.• After a pattern has been traced, the SLA’s elevator

platform descends by a single layer thickness, typically 0.05mm to 0.15mm. Then, a resin filled blade sweeps across the part cross section,recoating it with fresh material.

SELECTIVE LASER SINTERING (SLS)• Is a layer additive production process that creates three

dimensional object using CO2 laser to melt, or sinter and fuse selective powder molecules based on information supplied by a computer aided design (CAD) file.• Commonly called thermoplastic material or in some

cases, thermoplastic binders for use in metals. • Allows for these materials to be fused together in tiny

layers ranging between .003” and .006”.• Parts and or assemblies that move and work that have a

good surface finish and feature detail.• SLS gives the capability of flexible snaps and living

hingers as well as high stress and heat tolerance.

BALLISTIC• The BPM personal modeler came with all hardware and

software enclosed in one compact unit.• The BPM utilized ink jet or droplet based manufacturing

techniques, it builds the models by firing micro droplets of molten wax material from a moving nozzle or jet onto a stationary platform, the platform then lowers and the process is repeated for each layer of the model.• The parts can be scaled, rotated or translated to a desired

orientation. This is performed on a 5 axis workstation.

LAMINATED• That uses a carbon dioxide laser to create

successive cross section of a three dimentional object from layers of paper with a polythylene coating on the backside. The first step is to creates a base om which the paper can attach itself.

HIGHLIGHTS OF LAMINATED OBJECT MANUFACTURING• Layers of glue-backed paper form the model.• Low cost:Raw material is readily availabel.• Large parts: Because there is no chemical reaction

involved,parts can be made quite large.• Accuracy in z is less than that for sterrolithography and

selective laser sintering . No milling step• Outside of model,cross –hatching removes material• Model should be sealedin order to prohibit moisture.• Before sealing ,models have a wood-like texture.• Not as prevalent as stereolithograhy and selective laser

siterning.

METHODOLOGY FOR RP PROCESS The basic methodology for all current rapid prototyping techniques can be summarized as follows:

1. A CAD model is constructed, then converted STL format . The resolution can be set to minimize stair stepping.

2. The RP machine processes the STL file by creating sliced layers of the model.

3. The fisrt layer of the physical model is created .The model is then lowered by the thickness of the next layer, and the process is repeated until completion of the model

4. The model and any supports are removed. The surface of the model is then finished and cleaned.

RAPID TOOLING• A process that is the result of combining Rapid

Prototyping techniques with conventional tooling practices to produce a mold quickly or part of a functional model from CAD data in less time and at lower cost relative to traditional machining method .Rapid Tooling can act as brige to production injection molded parts.• The main advantage are tooling time is much shorter than

for a conventional tool. Time to first articles can be less than one fifth that of conventional tooling; tooling cost is much less than for a conventional tool. Cost can be below five percent of conventional tooling cost.• The main challrnges are tool life is less than for

conventional tools and tolerances are wider than for conventional tools.

TYPES OF RAPID TOOLING PROCESS-Low Volume (from tens to hundreds)- Soft tooling-Reaction injection molding-Bridge Tooling –Direct Access Injection Molding Intermediate (from hundreds to thousands)- Metal filled epoxy tooling- Powdered metal tooling - space puzzle molding