Report on Rapid Pro to Typing Using Various Technologies Latest.

8/8/2019 Report on Rapid Pro to Typing Using Various Technologies Latest.

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RAPID PROTOTYPING USING

VARIOUS TECHNOLOGIES.

Submitted in partial fulfilment of the requirements

For the degree of

Bachelor of Technology

By

AMEY VIDVANS(Roll No. U07PR849)

Supervisor:

DR.A.A.SHEIKH

MECHANICAL ENGINEERING DEPARTMENT

S.V. NATIONAL INSTITUTE OF TECHNOLOGY

SURAT

NOVEMBER -2010


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Topics

y Introduction , history and evolution

y The process

y Machines and software

y Rapid prototypingtechnologies

y Special focus on Stereo lithography

y Use ofrapid prototyping in various industries.

y Comparisonwith subtractive manufacturing processes.

y The Indian scenario and future ofrapid prototyping


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INTRODUCTION ,HISTORY AND EVOLUTION

Introduction.

The competition of manufactured products has increased tremendously in the past few years.It is now imperative to speed up the product development process so that new products may

reach the market quickly and before the competitors products. To do this various techniqueshave been introduced in the design , development and testing stages.one such technique is

rapid prototyping. Rapid prototyping allows the designers to test the feel , appearance of theproduct before it actually goes in to production.What is a prototype?From the engineering point of view a prototype is an approximation of a product or itscomponents in some form for a definite purpose in its implementation.

There are 4 main types of prototypes1) Solid image

Used for checking visual appearance and proportions

2) Geometric prototype

Verification of handling use and operation.

3) Functional prototype

Investigation of one or more functionalities

4) Technical prototype

Almost identical to production part. However a different manufacturing process is

used.

The functions of prototypes can stated as follows.

y Experimentation and learning

y Testing and proofing

y Communication and interaction

y Synthesis and integration

y Scheduling

Rapid Prototyping (RP) is a term most commonly used to describe a variety of processes,which are aimed at quickly creating three-dimensional physical parts from virtual 3Dcomputer models using automated machines. The parts are built directly from the 3D CADmodel and can match that model very closely (within the precision limits of the chosen

process).Rapid prototyping is different from traditional fabrication in that it is only possiblethrough the use of computers,


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both to generate the 3D CAD model data, as well as to control the mechanical systems of themachines that build the parts. Virtually all RP processes are additive. Parts are built up by

adding, depositing, or solidifying one or more materials in a horizontal layer-wise process.The part is built up layer by layer until done.

In addition to additive production processes, one must also consider the possibilities of

subtractive processes such as CNC machining and laser cutting. Subtractive processes, as thename implies, create objects by removing unwanted material from a large block or sheet inthe form of chips. CNC machining of 3D CAD models (normally called CAD/CAM) is notactually considered a rapid prototyping process (although it can be as fast), but both additiveand subtractive approaches are important aspects of todays prototyping industry. RPtechnologies are able to create one-piece part geometries which would be difficult if notimpossible to create by machining, including overhangs, undercuts and enclosed spaces. Tocreate these types of structures RP technologies often rely on a support material, which isused alongside the model material. These automatically generated supports must be removedafter the part is finished. Other processes rely on the unused model material to support the

part being built. However, machining is still able to produce finer surfaces, more accurate andlarger parts in a much wider variety of materials than RP processes are currently able to, and

complex models may often be built up out of assemblies of simpler, easier to machine parts.Thus, the two types of technologies, additive and subtractive, continue to co-exist and be

complimentary in the 3D prototyping world. The materials which are available for RP usewill depend on the process chosen and are still relatively limited, but the variety is growing.

There are a number of plastics and resins commonly used, as well as some process that canuse things like starch, plaster, wax and metal.

The word Rapid in RP is a relative term, as most of these processes are actually quite slow.The rapid actually refers to the reduced time from initial design to the production of the final

part. This is due to the elimination of extensive amounts of hand and machine work involvedin making prototypes with traditional methods, as well as the ability to quickly iterate and testa design through various stages. Also, as contrasted with more complicated CAM

programming and CNC machining, RP software and machines are generally simple and quickto use, resulting in significantly reduced human time needed to produce prototype parts.

RP processes are generally quiet, non-dangerous processes which can run in an officeenvironment 24/7. This contrasts with machining, which generally needs a workshop orfactory environment (noise, dust, liquids) and has a number of safety issues (including

personal injury or the possible destruction of the machine if things are not done properly).

History and evolution of rapid prototyping.

Rapid prototyping as it is known today was conceptualized by Professor Voeckler while he

was at University of Rochester. At that time , Professor Voeckler observed that all machining

processes involved cutting away excess material from the slab of metal. He wondered if hecould build the product layer by layer. Thus he designed mathematical algorithms and

mathematical modelling tools required for this. His ideas were implemented in the 1970s by

professor Deckard of the University of Texas. Deckard took his ideaconsidered too

speculative by industryto NSF(a research body in the USA), which awarded him a $50,000

Small Grant forExploratory Research (SGER) to pursue what he called "selective laser

sintering." Deckard's initial results were promising and in the late 1980s his team was

awarded one of NSF's first Strategic Manufacturing (STRATMAN) Initiative grants, given to


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the kind of interdisciplinary groups often necessary for innovation in the realm of

manufacturing.

The other person who has made a significant contribution to rapid prototyping is Charles

Hull. He developed the technology known as stereo lithography and acquired a patent for it.

He is therefore known as the father of modern day rapid prototyping. Rpaid prototyping

evolved from an experimental technique to a fully fledged technology due to the efforts of the

above mentioned people.

.

THE PROCESS


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The approach to rapid prototyping can be described as follows. It consists of 4 primary areas

The first is the input which consists of the following parts.

ModellingIn this a model of the product is made in any of the modelling softwares like AUTOCAD,PRO-E. There are however some restrictions on the types of models. All models shoul consistof closed surfaces. In general, what is needed is one or more completely closed volumes. TheRP software may be able to understand and automatically correct small openings and errors,

but large holes or open objects will result in not being able to print (without the file beingfirst repaired).Conversion.

In this stage the prepared file is converted into a file format called the STL(stands for stereolithography made by 3D systems). Since different programs work in different ways and havedifferent file formats, it will be necessary totranslate the representation of the model in thatsoftware into something more universal that the RP software can understand. Thistranslation process (like any translation) can introduce problems into the process that werenot apparent in the original.In general, from the 3D CAD software, we need to export the model as a .STL file. Nearly all3D

programs can export an STL and most can import them.This file is an approximation of theoriginal model made using polygons. Depending upon the surface the file size may vary. Forcurved surfaces the number of polygons used is high so the file size is also big.

Slicing.In this a computer program slices the generated STL file into layers which defines the

product to be fabricated. An STL is a type of standardized computer exchange file whichcontains a 3D model. The representation of the surface(s) of the object(s) in the file is in theform of one or more polygon meshes. The polygon meshes in an STL file are entirelycomposed of triangular faces, edges and vertices. Further, the faces have assigned normalswhich indicate their orientation (inside/outside).. The file format has become a world standard for exchanging 3D polygon mesh type objects

between programs, and .stls are now used as input for virtually all rapid prototypingprocesses, as well as some 3D machining The layers or cross sections are manufactured bysolidification of liquids or powders and joined together to from the product. The thickness ofthe layer depends upon the type of accuracy required.

Once the .stl is 100% correct and verified, it can then be imported into the machine-specific

RP software which will generate the commands to run the machine. This data is then sent tothe machine (like a printer) and the model construction is started. However some holes orimperfections in the STL file are permissible.


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Non-uniform rationalbasis spline (NURBS) is a mathematical model commonly used in

computer graphics for generating and representing curves and surfaces which offers great

flexibility and precision for handling both analytic and freeform shapes.


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The second is the method.

There are more than 30 vendors worldwide in the rapid prototyping industry and thetechnology used varies from vendor to vendor. There are various classifications of the

methods used based on the physical effect, type of curing.etc This will be discussed in detailin the coming topics. This area is concerned with the selection of the proper method for RP.

During the approach 2 other areas to be kept in mind are the material considerations and theapplications. For example , the material aspect deals with whether the state of the materialwhich solidifies will affect the product. The material may be in liquid , solid or powder form.Generally the solid materials come in the form of pallets, wires or laminates. Also theapplication of the prototype will affect the RP process. It should be known whether the

product is required for tooling , manufacturing or for some other purpose .

The sliced STL file is entered into an RP machine and thus the product is made. There are

several other things to be considered during the design of the model like overhang , supportmaterials, base materials. During the finishing stages the support material is stripped off the

product .

Clasiification of the RP systems according to state of material.

Liquid based.

1. 3D systems stereolithography apparatus

2. Cubitals solid ground curing3. Sonys solid creation system

4. Auto strades E darts5. Teijin seki soliform method.

6. Microfabrication7. Denkens SLP

8. Aaroflex9. Light sculpting

Powder based

1. 3D systems selective laser sintering2. Fraunhofers multiphase jet solidification3. Acrams electron beam melting4. Aeromets lasform technology5. Generis RP systems6. Extrudes prometal.


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Solid based

1. Cubic technologies LOM2. 3D systems multijet modelling

3. Solidscapes model maker and patternmaker4. Stratsys fused deposition modelling.

Machines and softwares.

MachinesSpecial machines are required to manufacture the product. The machines may be based on

any of the above mentioned technologies. The machines are expensive and prices vary frommanufacturer to manufacturer. The actual mechanisms on which these machines operate will

be explained later.


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This is a photograph of a Z corp printer RP system.

Photograph of an SLA printer manufactured by 3D systems.


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An LOM (laminted object manufacturing) machine


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This is a photograph of a SLS machine

This is a photograph of a fused deposition modelling machine


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.

Softwares.As mentioned earlier we require powerful mathematical modelling tools and algorithms to convert

the models into STL files and subsequently into slices or layers which can be fabricated accordingly.The programs that do this job are call RP softwares. Also in the case of reverse engineering there is aneed of several other programs which acquire data and feed the same to the system for RP.There areas in the case of machines several software coders who are involved in this. Some of their productsare mentioned below.

3 D systems lightyear

3D Lightyear file preparation software is used on Windows-based CAD/CAM or otherworkstations to prepare STL and SLC files for part building on the SLA system.

3D Lightyear software inputs STL or SLC files, which it then prepares for part building on

any of 3D Systems SLA systems. An industry standard, STL files are routinely produced byvirtually all significant CAD/CAM software programs, and a large variety of scanning ortooling-related software, as well as a variety of commercially-available third-partyconversion/utility programs.

Materialise

Offers the free MiniMagics software for STL inspection and compression (up to a factor of20). MiniMagics makes project communication easy, with the functionality to addannotations to STL files and a variety of visualization options.

Z tech solutions

Provides Ztech-STL for viewing and repairing STL files. Multiple files can be handledsimultaneously and the program is said to offer advanced tools to prepare data for rapid

prototyping

There are other various softwares for sending STL files through email, compressing the STLfiles., converting from STL to other formats.etc.


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Rapid prototyping technologies.

The following are the rapid prototyping technologies which are most widely used.

In the following article a brief description will be provided on each of these technologies anda special emphasis will be on stereo lithography as it is the oldest and gives the best results.Also the materials that can be used in these technologies will be discussed.

Stereolithography.

Stereolithography is the most widely used rapid prototyping technology. Stereolithographybuilds plastic parts or objects one layer at a time by tracing a laser beam on the surface of avat of liquid photopolymer, inside of which is a movable stage to support the part being built.The photopolymer quickly solidifies wherever the laser beam strikes the surface of the liquid.

Once one layer is completely traced, the stage is lowered a small distance into the vat and asecond layer is traced directly on top of the first.the distance moved by the table depends onthe accuracy required. The self-adhesive property of the material causes each succeedinglayer to bond to the previous one and thus form a complete, three-dimensional object out ofmany layers.Objects which have overhangs or undercuts must be supported during the fabrication process

by support structures. These are either manually or automatically designed with a computerprogram specifically developed for rapid prototyping. Upon completion of the fabrication

process, the object is removed from the vat and the supports are cut or broken off.

1. Selective laser sintering (SLS)

2. Fused deposition modeling (FDM)

3. Stereolithography (SLA)

4.

Laminated object manufacturing (LOM)

5. Electron beam melting (EBM)

6. 3D printing


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Stereolithography generally is considered to provide the greatest accuracy and best surfacefinish of any rapid prototyping technology. Over the years, a wide range of materials with

properties mimicking those of several engineering thermoplastics have been developed.Limited selectively color changing materials for biomedical and other applications are

available, and ceramic materials are currently being developed. The technology is alsonotable for the relatively large size range of objects possible, from parts as big as a car wheel

to as small as a sugar cube, with excellent accuracy relative to the scale of the object. On thenegative side, the photopolymers are expensive and perishable, working with liquid materialscan be messy and parts require a post-curing operation in a separate oven-like apparatus forcomplete cure and stability.

The liquid based material used is highly expensive and prices range from $400 to $500 for agallon. This puts the technology out of range of several small small enterprises. Howeverthere are some corporations that provide these machines on a time sharing basis for 25dollars an hourPrincipal commercial providers: 3DSystems, Aaroflex, envisionTEC (non-laser

stereolithography)Materials: Principally photo curing polymers which simulate polypropylene, ABS, PBT,

rubber; development of ceramic-metal alloys.

The following is a schematic figure of the stereolithography.


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A photopolymer is a polymer that changes its properties when exposed to light, often in the

ultraviolet spectrum. These polymers are useful in rapid prototyping in the stereolithography

and 3D printing processes. These are cured as mentioned above. Curing means irradiation ofultraviolet light int his case to solidify the polymer.

The object below is a example of the type products obtained and also gives a rough ideaabout the surface finish obtained. This is the inlet manifold of a multicylinder engine.


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Laminated object manufacturing .

Profiles of object cross sections are cut from paper or other web material using a laser. The

paper isunwound from a feed roll onto the stack and first bonded to the previous layer using a heated

roller which melts a plastic coating on the bottom side of the paper. The profiles are thentraced by an optics system that is mounted to an X-Y stage. After cutting of each layer iscomplete, excess paper is cut away to separate the layer from the web. Waste paper is woundon a take-up roll. The method is self-supporting for overhangs and undercuts. Areas of crosssections which are to be removed in the final object are heavily cross-hatched with the laserto facilitate removal. It can be time consuming to remove extra material for some partgeometries, and there is a lot of inherent waste in the process, as every object uses up anamount of material equivalent to a box that contains the part - even if the part itself is verythin walled. Variations on this method use a knife to cut each layer instead of a laser or applyadhesive to bond layers using the xerographic process. There are also variations which seek

to increase speed and/or material versatility by cutting the edges of thick layers diagonally toavoid stair stepping. In general, the finish, accuracy and dimensional stability of paper objects

are not as good as for materials used with other RP methods. In addition, the laser cutting ofthe material creates a lot of smoke and needs to be ventilated to the outside. However,

material costs are very low, and objects have the look and feel of wood and can be workedand finished in the same manner. This has fostered applications such as patterns for sand

castings. While there are limitations on materials, work has been done with plastics,composites, ceramics and metals


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Principal commercial providers: Helisys (paper); 3DSystems (plastic)Materials: Typically paper rolls but recently also plastic films

Selective laser sintering

Thermoplastic powder is spread by a roller over the surface of a build cylinder. The piston inthecylinder moves down one object layer thickness to accommodate the new layer of powder. A

piston movesupward incrementally to supply a measured quantity of powder for each layer.A laser beam is traced over the surface of this tightly compacted powder to selectively meltand weld the grains together to form a layer of the object. The fabrication chamber ismaintained at a temperature just below the melting point of the powder so that the laserelevates the temperature slightly to cause sintering - the grains are not entirely melted, justtheir outer surfaces - which greatly speeds up the process. The process is repeated, layer bylayer, until the entire object is formed.

After the object is fully formed, the piston is raised. Excess powder is simply brushed awayand finalmanual finishing may be carried out. No supports are required with this method sinceoverhangs and undercuts are supported by the solid powder bed. It takes a considerable cool-down time before the part can be removed from the machine. Large parts with thin sectionsmay require as much as two days of cooling. SLS offers the key advantage of making largesized functional parts in essentially final materials. However, the system is mechanicallymore complex than stereolithography and most other technologies. A variety of thermoplasticmaterials such as nylon, glass filled nylon, and polystyrene are available. Surface finishes andaccuracy are not as good as with stereolithography, but material properties can be quite closeto those of the intrinsic materials. The method has also been extended to provide directfabrication of metal and ceramic objects and tools.Since the objects are sintered they are porous. It may be necessary to infiltrate the part,especially metals, with another material to improve mechanical characteristics.Laser Sintering parts typically have a grainy surface but all kinds of (very) fine finishing are

possible. They can be sandblasted, coloured to improve surface quality.


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An example of the product manufactured by selective laser sintering.

Principal commercial providers: 3D systems, DTM Corporation, EOSMaterials: Plastics -polystyrene, nylon, glass filled nylon, alumide (aluminum/nylon blend),Materials: Metals - aluminum, stainless steel, titanium, gold (virtually any metal can be

sintered

Fused deposition modelling

FDM is the second most widely used rapid prototyping technology, after stereolithography. Aplasticfilament is unwound from a coil and supplies material to an extrusion nozzle. The nozzle isheated to melt the plastic and has a mechanism which allows the flow of the melted plastic to

be turned on and off. The nozzle is mounted to an X-Y plotter type mechanism which tracesout the part contours, There is a second extrusion nozzle for the support material (differentfrom the model material).

As the nozzle is moved over the table in the required geometry, it deposits a thin bead ofextruded plastic to form each layer. The plastic hardens immediately after being squirtedfrom the nozzle and bonds to the layer below. The object is built on a mechanical stage whichmoves vertically downward layer by layer as the part is formed. The entire system iscontained within a chamber which is held at a temperature just below the melting point of the

plastic.Several materials are available for the process including ABS and investment casting wax.ABS offersgood strength, while the polycarbonate (PC) and polyphenylsulfone (PPS) materials offermore strength and a higher temperature range. Support structures are automatically generatedfor overhanging geometries and are later removed by breaking them away from the object. Awater-soluble support material is also available for ABS parts. The method is office-

friendly and quiet. FDM is fairly fast for small parts on the order of a few cubic centimetres.It can be very slow for large parts with a lot of volume, however. Depending on the partgeometry and orientation,it can also require more support material than the part itself (or virtually none). The finished

parts areanisotropic, that is they exhibit different mechanical characteristics in different directions.The resolution is not as fine as with stereolithography, but the parts are more robust.


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3 dimensional printing

Three dimensional printing was developed at MIT. It's often used as a direct manufacturingprocess aswell as for rapid prototyping. The process starts by depositing a layer of powder objectmaterial at the top of a fabrication chamber. To accomplish this, a measured quantity of

powder is first dispensed from a similar supply chamber by moving a piston upwardincrementally. A roller or scraper then distributes and compresses the powder at the top of thefabrication chamber. The multi-channel jetting head subsequently deposits a liquid adhesive(binder) in a two dimensional pattern onto the layer of the powder (similar to inkjet printing).The binder bonds the powder particles together where it has been deposited, solidifying it toform a layer of the object. Once a layer is completed, the fabrication piston moves down byone layer thickness, and the process is repeated until the entire object is formed within the

powder bed. After completion, the object must be removedfrom the chamber still filled with powder (a delicate operation), and the excess powder

brushed off, leaving a green" object. No external supports are required during fabricationsince the powder bed supports overhangs. Three dimensional printing offers the advantagesof speedy fabrication and low materials and system cost. In fact, it's probably the fastest of all

RP methods. It is even possible to print colored parts and images onto the part surfaces.However, there are limitations on resolution, surface finish, part fragility and availablematerials. In order to face the problem of the fragility of the standard 3DP plaster and starch

parts, the object can be infiltrated with a resin, which hardens the object once it cures, buteven then the break resistance does not equal that of some other systems such as FDM. 3D

printing is also being used with sand and a high temperature resin to create sand castingmolds and cores for metal casting, as well as acrylic for creating plastic prototype parts.


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Electron beam melting

This solid freeform fabrication method produces fully dense metal parts directly from metalpowder with characteristics of the target material. The EBM machine reads data from a 3DCAD model and lays down successive layers of powdered material. These layers are meltedtogether utilizing a computer controlled electron beam. In this way it builds up the parts. The

process takes place under vacuum, which makes it suited to manufacture parts in reactivematerials with a high affinity for oxygen, e.g. titanium.

The melted material is from a pure alloy in powder form of the final material to be fabricated(no filler). For that reason the electron beam technology doesn't require additional thermal

treatment to obtain the full mechanical properties of the parts. That aspect allowsclassification ofEBM with selective laser melting (SLM) where competing technologies like

SLS and DMLS require thermal treatment after fabrication. Comparatively to SLM andDMLS, EBM has a generally superior build rate because of its higher energy density andscanning method.

The EBM process operates at an elevated temperature, typically between 700 and 1.000 C,producing parts that are virtually free from residual stress, and eliminating the need for heattreatment after the build.


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Special focus on stereo lithography .

Reasons to choose stereolithography over other technologies

y Fast: Parts in as little as 2 days

y High level of accuracy and high surface quality

y Representative parts for visual testing

y Functional parts

y Small and large parts - from intricate switch component to car dashboard built in asingle piece

y Wide range of finishing options

y Wide range of materials

y Design complexity is not an issue

y There are many service bureaus offering this technology at reasonable rates.

Use of rapid prototyping in various industries

Rapid Prototyping models are no longer used only for design verification.

This is cutting edge technology, which can be applied to almost every industry. Thefollowing are some industries that use rapid prototyping: design & engineering, R & D,consumer products, electronics, aerospace, automotive, robotics, appliances,telecommunications, orthopedics, healthcare, dental, foundry, oil & gas, petrochemical, oilrefining, power, marine, medical, toys and plastics.

AerospaceThe aerospace industry has been one of the early adopters of rapid manufacturing technology.Parts for aircraft are made in small quantities, are often complex and must meet stringentrequirements. Price is almost always secondary to function. This is essentially the definitionof a high value-added application - which is exactly the type of application that rapidmanufacturing is most appropriate for at present. Parts for the International Space Station and


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other projects were being made as long as several years ago by Boeing using selective lasersintering. In 2002, the company spun off BoeingOn-Demand Manufacturing (ODM) to

independently pursue the market for rapid manufactured parts. The company still gets muchof its business from Boeing, fabricating items such as air-ducts and ventilating components

for aircraft. Making these complex parts in a single piece without tooling provides significantcost and time-saving advantages over conventional methods. Applications will increase over

time for both plastic and metal parts as materials improve and are flight qualified.

MarineMarine applications of rapid manufacturing have some aspects in common with those foraerospace, and others with those for architectural construction. From the early days of rapid

prototyping, it's been a goal to provide spare parts for naval vessels at sea. Early RP efforts inweld deposition were at least in part driven by this application, although laser powderforming technologies have lately received the most attention.

Like aircraft, watercraft are also manufactured in relatively small numbers and use parts thatcan be geometrically complicated. Although the parts are still costly, marine applications arenot quite at the same lofty high value-added level as aircraft. Nevertheless, this segment stilloffers significant long-term possibilities, although it may not be quite the market-propelling

force that aerospace applications have been.

Automobile

Several body part for prototypes are made using RP. The examples of parts made by RP are

given below. The Audi RSQ was made by Audi with rapid prototyping industrial KUKA

robots. This proves that the market for automobile rapid prototyping is expanding .

Some examples of RP products used in automobiles.

y Engine castings and parts

y Auto Body Components

y Auto Mechanical parts

y Car Dashboards

y Car Handles and Knobs

y Car Trim parts

Biomedical industry

Stereolthography is being used to create prosthetic limbs and other body parts. It cancorrectly scan a patients body to optimize the shape of the limb. Also recently prostheticears have been created using stereolithography.


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Comparison with subtractive manufacturing processes.

Using computer controlled cutting machines to create parts with a subtractive type material-removal

procedure is no longer considered rapid prototyping, but it is included here because it is stillan important, widely used technique for creating prototype as well as production parts.

The process of creating machined parts from 2D or 3D CAD models is generally known asCAD/CAM (Computer Aided Design/Computer Aided Machining or Manufacturing).CAD/CAM represents the software and programming part of this manufacturing procedure.Its output is then sent to CNC (Computer Numerical Controlled) machines for physically

producing parts by cutting away unwanted material from solid blocks. The most commonlyused CNC controlled machines for creating 3D parts are milling machines and lathes.In milling, a block of material is clamped to the table of the machine, and a rotating cuttingtool held in the machine spindle moves around the block, removing material from it in the

form of chips. In a lathe, it is the material that is rotated in the spindle and a stationary sharpcutting tool moved across the work to remove the chips. Both of these processes are

subtractive, lathes being mostly used to produce parts of round cross section (as the material

is turning), milling machines being used to produce rectilinear or free-form parts. There arealso machines that combine these two functions.The advantage of these types machines and processes is that virtually any material can beworked, andthe size range of the process is much larger than that of rapid prototyping. CNC machiningcan make parts that range from nearly microscopic watch parts to entire boat hull molds 30mlong, in any material from metal to plastics to wood to composites. In general these rawmaterials are also much less expensive than the special materials needed by RP machines.In a CNC controlled machine, the material and/or the tool movements are executed by motorsthat arecontrolled by the machines computer. The computer control allows the machine to move in avery precise and controlled way, resulting in very precise machined parts that would beimpossible to create with conventional (hand-operated) machine tools.The machine needsdata to make the part, however. While simple parts can actually be programmed right at themachine using a special programming language, for more complex objects, a computer modelis needed, as well as a way to interpret the model data so that the machine can cut the partcorrectly


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The Indian scenario in rapid prototyping.

Indian companies have acknowledged the need for rapid prototyping and have adopted it in theirdesign and research laboratories. Several companies like Marcopolo ,lovson serve the Indian market.Several FMCG, automobile and home appliance majors are on its clients list. Rapid prototyping

however still remains a relatively untouched market in India. There is wide scope for development ofRP in India. There is also a Rapid Prototyping Society of India which is a not for profit

organisation.working under the aegis ofNational Design and Research Forum, Bangalore. Itundertakes assignments like holding of seminars and demonstrations for the progress of rapid

prototyping.Several of our companies are involved in research and are competing with the multinationals all overthe world.

Future of rapid prototyping.

The future of rapid prototyping is very bright as research into increasing the speed and accuracy isgoing on in various research labs and universities across the world. In the future there is a possibilityof rapid prototyping used in biological applications like duplicating of tissues using special polymers,duplicating skin like material for use in surgery. Very soon designers might be able to send signals todesktop 3d printers to make a certain product almost instantly right before the designers eyes.Consumers might be able to order a product they like and the domestic RP system(in development)will make the product according to the customers specifications. After its use the customer candiscard the product send it for recycling. This reduces the storage space required in the house.

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