Abstract

Six Stroke engine, the name itself indicates a cycle of six strokes out of which two are useful

power strokes. According to its mechanical design, the six-stroke engine with external and

internal combustion and double flow is similar to the actual internal reciprocating combustion

engine. However, it differentiates itself entirely, due to its thermodynamic cycle and a

modified cylinder head with two supplementary chambers: combustion and an air heating

chamber, both independent from the cylinder. In this the cylinder and the combustion

chamber are separated which gives more freedom for design analysis. Several advantages

result from this, one very important being the increase in thermal efficiency.

It consists of two cycles of operations namely external combustion cycle and internal

combustion cycle, each cycle having four events. In addition to the two valves in the four

stroke engine two more valves are incorporated which are operated by a piston arrangement.

The Six Stroke is thermodynamically more efficient because the change in volume of the

power stroke is greater than the intake stroke and the compression stroke. The main

advantages of six stroke engine includes reduction in fuel consumption by 40%, two power

strokes in the six stroke cycle, dramatic reduction in pollution, adaptability to multi fuel

operation. Six stroke engine's adoption by the automobile industry would have a tremendous

impact on the environment and world economy.

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Chapter-1

INTRODUCTION

In 1994, Malcolm Beare, a self-taught enginner from a small south Australian town named

Bordertown, invented a revolutionary and an innovative hybrid design of the I C Engine by

combining a two-stroke engine with a four-stroke engine. He worked for 16 years on his

design, building three engines in his farm workshop and the fourth in his engineering

premises, to successfully invent the Six-Stroke Engine.

Used to repairing badly-designed farm machinery and frequently redesigning it, Mr Beare

started thinking about poppet valves and camshafts, and decided there had to be a better way.

Rotary valves are quiet, compact, and cheap to manufacture, but difficult to lubricate.

Mr Beare than borrowed the basic components of a rotary disc induction two-stroke and

grafted it onto a four-stroke motor. In doing so he had taken combustion pressure off the

rotary valve during the period when temperatures and pressures are highest.

A small upper piston forms the roof of the combustion chamber. It takes the brunt of the gas

sealing and the part of the valving, the opening of the exhaust port and the closing of the

intake. The upper porting piston is connected to a small crank driven at half main crank

speed.

The main crank does the normal four strokes, while the upper porting piston does two

strokes, making six strokes for a complete cycle. During the power stroke approximately 12%

of the power is transmitted through the upper piston. The main piston loses about three

percent, therefore there is a net gain of nine percent, all things being equal.

The crown of the upper piston remains at a much more even temperature, unlike the roof of a

conventional combustion chamber, where the exhaust poppet valve is the hottest area.

Therefore a gain in thermodynamic efficiency is evident, because a significant increase in

compression ratio can be achieved without the onset of detonation or pre-ignition – lower

octane number or unleaded petrol is no problem. Mr Beare envisages a gain from

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approximately 9:1 to 10.5:1, or compression pressure of approximately 200-220 lbs/sq inch,

from the standard of 150 lbs/sp inch.

The unique design provides advantages in power, efficiency and quietness over current

engines.

The prototype has been installed in a 500cc motorcycle but the design can be adapted to any

four-stroke, overhead camshaft engine and could eventually be used in trucks and passenger

cars.

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Chapter-2

HISTORY

The six-stroke engine is a type of internal combustion engine based on the four-stroke engine,

but with additional complexity intended to make it more efficient and reduce emissions. Two

types of six-stroke engine have been developed since the 1990s:

In the first approach, the engine captures the heat lost from the four-stroke Otto

cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the

piston in the same cylinder. Designs use either steam or air as the working fluid for the

additional power stroke. The pistons in this type of six-stroke engine go up and down three

times for each injection of fuel. There are two power strokes: one with fuel, the other with

steam or air. The currently notable designs in this class are the Crower six-stroke engine,

invented by Bruce Crower of the U.S.; the Bajulaz engine by the Bajulaz S.A. company of

Switzerland; the Velozeta Six-stroke engine built by the College of Engineering, at

Trivandrum in India; and the NIYKADO Six Stroke Engine invented by Chanayil Cleetus

Anil, NIYKADO Motors, India under patent number IN252642 granted on 25 May 2012.

The second approach to the six-stroke engine uses a second opposed piston in each cylinder

that moves at half the cyclical rate of the main piston, thus giving six piston movements per

cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine

but also increases the compression ratio. The currently notable designs in this class include

two designs developed independently: the Beare Head engine, invented by Australian

Malcolm Beare, and the German Charge pump, invented by Helmut Kottmann.

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Chapter-3

BASIC PRINCIPLES OF RAPID PROTOTYPING PROCESSES

Rapid Prototyping process belong to the generative (or additive) production processes unlike

subtractive or forming processes such as lathing, milling, grinding or coining etc. in which

form is shaped by material removal or plastic deformation. In all commercial RP processes,

the part is fabricated by deposition of layers contoured in a (x-y) plane two dimensionally.

The third dimension (z) results from single layers being stacked up on top of each other, but

not as a continuous z-coordinate. Therefore, the prototypes are very exact on the x-y plane

but have stair-stepping effect in z-direction. If model is deposited with very fine layers, i.e.,

smaller z-stepping, model looks like original. RP can be classified into two fundamental

process steps namely generation of mathematical layer information and generation of

physical layer model. Typical process chain of various Rapid Prototyping systems is shown

in figure.

Figure 3.1 RP process chain showing fundamental process steps

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Although several rapid prototyping techniques exist, all employ the same basic five-step

process. The steps are: 

1. Create a CAD model of the design

2. Convert the CAD model to STL format

3. Slice the STL file into thin cross-sectional layers

4. Construct the model one layer atop another

5. Clean and Finish the model

3.1 CAD Model Creation: First, the object to be built is modeled using a Computer-

Aided Design (CAD) software package. Solid modelers, such as Pro/ENGINEER, tend to

represent 3-D objects more accurately than wire-frame modelers such as AutoCAD, and will

therefore yield better results. The designer can use a pre-existing CAD file or may wish to

create one expressly for prototyping purposes. This process is identical for all of the RP build

techniques. 

3.2 Conversion to STL Format: The various CAD packages use a number of different

algorithms to represent solid objects. To establish consistency, the STL (stereo lithography,

the first RP technique) format has been adopted as the standard of the rapid

prototyping industry. The second step, therefore, is to convert the CAD file into STL format.

This format represents a three-dimensional surface as an assembly of planar triangles, "like

the facets of a cut jewel". The file contains the coordinates of the vertices and the direction of

the outward normal of each triangle. Because STL files use planar elements, they cannot

represent curved surfaces exactly. Increasing the number of triangles improves the

approximation, but at the cost of bigger files size. Large, complicated files require more time

to pre-process and build, so the designer must balance accuracy with manageability to

produce a useful STL file. Since the STL format is universal, this process is identical for all

of the RP build techniques.

3.3 Slice the STL File: In the third step, a pre-processing program prepares the STL file

to be built. The standard data interface between CAD software and the machine is the STL-

format (Stereolithography).

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An STL-file approximates the shape of a part using triangular facets. Small facets produce a

high quality surface. Several programs are available, and most allow the user to adjust the

size, location and orientation of the model. Build orientation is important for several reasons.

First, properties of rapid prototypes vary from one coordinate direction to another. For

example, prototypes are usually weaker and less accurate in the z (vertical) direction than in

the x-y plane. In addition, part orientation partially determines the amount of time required to

build the model. Placing the shortest dimension in the z direction reduces the number of

layers, thereby shortening build time. The pre-processing software slices the STL model into

a number of layers from 0.01 mm to 0.7 mm thick, depending on the build technique. The

program may also generate an auxiliary structure to support the model during the build.

Supports are useful for delicate features such as overhangs, internal cavities, and thin-walled

sections. Each RP machine manufacturer supplies their own proprietary pre-processing

software

Figure 3.2 General Methods employed for Rapid Prototyping

. 

3.4 Layer by Layer Construction: The fourth step is the actual construction of the

part. Using one of several techniques (described in the next section) RP machines build one

layer at a time from polymers, paper, or powdered metal. Most machines are fairly

autonomous, needing little human intervention.

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3.5 Clean and Finish: The final step is post-processing. This involves removing the

prototype from the machine and detaching any supports. Some photosensitive materials need

to be fully cured before use. Prototypes may also require minor cleaning and surface

treatment. At this stage, generally some manual operations are necessary therefore skilled

operator is required. In cleaning, excess elements adhered with the part or support structures

are removed. Sometimes the surface of the model is finished by sanding, polishing or

painting for better surface finish or aesthetic appearance and durability. Prototype is then

tested or verified and suggested engineering changes are once again incorporated during the

solid modelling stage.

Table 3.1 Generalized illustration of data flow in RP

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Chapter-4

EXAMPLE OF PROTOTYPING

Rapid prototyping is a technology that takes a three-dimensional computer model and builds

a three dimensional part by building layers upon layer of material. Its speed and low cost

allow design teams to confirm their new designs early and frequently in the process.

Step 1

Start with a 3 dimension computer model. Typically created in 3D CAD products like Solid

Works, Rhino, Pro/E, Mechanical Desktop etc.

Step 2

From 3D CAD, an STL file is exported. Typically done as a "File Save As …". Xpress3D

CAD Add-ins perform this step automatically.

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Step 3

The STL file is then translated into hundreds (or even thousands) of cross sectional data.

Step 4

Starting with the bottom slice, the prototyping machine builds each slice upon the previous,

until all the slices are built and the prototype is complete.

Step 5

Final Prototype

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Chapter-5

RAPID PROTOTYPING TECHNOLOGIES

The professional literature in RP contains different ways of classifying Rapid Prototyping

processes. Few important RP processes are namely:-

Steriolithography (SLA)

Fused Deposition modeling (FDM)

Selective Laser Sintering (SLS)

Laminated Object Manufacturing (LOM)

3D Printing

Direct Metal Laser Sintering (DMLS)

5.1 Steriolithography

Stereolithography is the most widely used RP-technology. It can produce highly

accurate and detailed polymer parts. SLA was the first RP-process, introduced in 1988 by 3D

Systems Inc.

In this process photosensitive liquid resin which forms a solid polymer when exposed to

ultraviolet light is used as a fundamental concept. Due to the absorption and scattering of

beam, the reaction only takes place near the surface and layers of solid polymeric resin are

formed. A SL machine consists of a build platform (substrate), which is mounted in a vat of

resin and a UV Helium-Cadmium or Argon ion laser. The laser scans the first layer and

platform is then lowered equal to one slice thickness and left for short time (dip-delay) so that

liquid polymer settles to a flat and even surface and inhibit bubble formation. The new slice

is then scanned. Schematic diagram of a typical Stereolithography apparatus is shown in

figure.

In new SL systems, a blade spreads resin on the part as the blade traverses the vat. This

ensures smoother surface and reduced recoating time. It also reduces trapped volumes which

are sometimes formed due to excessive polymerization at the ends of the slices and an island

of liquid resin having thickness more than slice thickness is formed. Once the complete part

is deposited, it is removed from the vat and then excess resin is drained. It may take long time

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due to high viscosity of liquid resin. The green part is then post-cured in an UV oven after

removing support structures.

Overhangs or cantilever walls need support structures as a green layer has relatively low

stability and strength. These overhangs etc. are supported if they exceed a certain size or

angle, i.e., build orientation. The main functions of these structures are to support projecting

parts and also to pull other parts down which due to shrinkage tends to curl up. These support

structures are generated during data processing and due to these data grows heavily specially

with STL files, as cuboid shaped support element need information about at least twelve

triangles. A solid support is very difficult to remove later and may damage the model.

Build strategies have been developed to increase build speed and to decrease amount of resin

by depositing the parts with a higher proportion of hollow volume. These strategies are

devised as these models are used for making cavities for precision castings. Here walls are

designed hollow connected by rod-type bridging elements and skin is introduced that close

the model at the top and the bottom. These models require openings to drain out uncured

resin.

Figure 5.1. Stereolithograph

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Abbreviation: SLA

Material type: Liquid(Photopolymer)

Materials: Thermoplastics(Elastomers)

Min layer thickness: 0.02mm

Surface finish: Smooth

Build speed: Average

Applications: Form/fit testing, Functional testing, Very detailed parts,

Presentation models, snap fits.

Table 5.1. Details for Stereolithography

5.2 Fused Deposition modeling (FDM)

FDM was developed by Stratasys. In this process, a plastic or wax material is extruded

through a nozzle that traces the part´s cross sectional geometry layer by layer.

In this process a movable (x-y movement) nozzle on to a substrate deposits thread of molten

polymeric material. The build material is heated slightly above (approximately 0.5 C) its

melting temperature so that it solidifies within a very short time (approximately 0.1 s) after

extrusion and cold-welds to the previous layer as shown in figure. Various important factors

need to be considered and are steady nozzle and material extrusion rates, addition of support

structures for overhanging features and speed of the nozzle head, which affects the slice

thickness. More recent FDM systems include two nozzles, one for part material and other for

support material. The support material is relatively of poor quality and can be broken easily

once the complete part is deposited and is removed from substrate. In more recent FDM

technology, water-soluble support structure material is used. Support structure can be

deposited with lesser density as compared to part density by providing air gaps between two

consecutive roads.

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Figure 5.2 Fused Deposition modeling (FDM)

Abbreviation: FDM

Material type: Solid (Filaments)

Materials: ABS, Polycarbonate, Poly phenyl sulfonite ; Elastomers

Min layer thickness: 0.15mm

Surface finish: Rough

Build speed: Slow

Applications: Form/fit testing, Functional testing, Very detailed parts,

Presentation models,

Table 5.2 Details for Fused Deposition modelling

5.3 Selective Laser Sintering (SLS)

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SLS was patented in 1989. The basic concept of SLS is similar to that of SLA. It uses a

moving laser beam to trace and selectively sinter powdered polymer and/or metal composite

materials. The powder is kept at elevated temperature. Unlike SLA, special support structures

are not required because the excess powder in each layer acts as a support.

In Selective Laser Sintering (SLS) process, fine polymeric powder like polystyrene,

polycarbonate or polyamide etc. (20 to 100 micrometer diameter) is spread on the substrate

using a roller. Before starting CO2 laser scanning for sintering of a slice the temperature of

the entire bed is raised just below its melting point by infrared heating in order to minimize

thermal distortion (curling) and facilitate fusion to the previous layer. The laser is modulated

in such a way that only those grains, which are in direct contact with the beam, are affected.

Once laser scanning cures a slice, bed is lowered and powder feed chamber is raised so that a

covering of powder can be spread evenly over the build area by counter rotating roller. In this

process support structures are not required as the unsintered powder remains at the places of

support structure. It is cleaned away and can be recycled once the model is complete. The

schematic diagram of a typical SLS apparatus is given in figure.

SLS allows for a wide range of materials, including nylon, glass-filled nylon, Truform

(investment casting) and metal composites.

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Figure 5.3 Selective Laser Sintering (SLS)

Abbreviation: SLS

Material type: Powder(Polymer)

Materials: Thermoplastics: Nylon, Poly amide and Polystyrene; Elastomers; Composites

Min layer thickness: 0.10mm

Surface finish: Average

Build speed: Fast

Applications: Form/fit testing, Functional testing, Less detailed parts, Parts with snap-fits& living hinges, High heat applications..

Table 5.3 Details for Selective Laser Sintering

5.4 Laminated Object Manufacturing (LOM)

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Typical system of Laminated Object Manufacturing (LOM) has been shown in figure. It can

be seen from the figure that the slices are cut in required contour from roll of material by

using a 25-50 watt CO2 laser beam. A new slice is bonded to previously deposited slice by

using a hot roller, which activates a heat sensitive adhesive. Apart from the slice unwanted

material is also hatched in rectangles to facilitate its later removal but remains in place during

the build to act as supports. Once one slice is completed platform can be lowered and roll of

material can be advanced by winding this excess onto a second roller until a fresh area of the

sheet lies over the part. After completion of the part they are sealed with a urethane lacquer,

silicone fluid or epoxy resin to prevent later distortion of the paper prototype through water

absorption.

Figure 5.4.1 Laminated Object Manufacturing (LOM)

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In this process, materials that are relatively cheaper like paper, plastic roll etc. can be used.

Parts of fiber-reinforced glass ceramics can be produced. Large models can be produced and

the building speed is 5-10 times as compared to other RP processes.

The limitation of the process included fabrication of hollow models with undercuts and re-

entrant features. Large amount of scrap is formed. There remains danger of fire hazards and

drops of the molten materials formed during the cutting also need to be removed.

Figure 5.4.2 Methodology of Formation of Laminated Object

Abbreviation: LOM

Material type: Solid (Sheets)

Materials: Thermoplastics such as PVC; Paper; Composites(Ferrous metals; Non-ferrous metals; Ceramics)

Min layer thickness: 0.05mm

Surface finish: Rough

Build speed: Fast

Applications: Form/fit testing, Less detailed parts, Rapid Tooling Patterns

Table 5.4 Details for Laminated Object Manufacturing

5.5 3D Printing

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Three Dimensional Printing (3DP) technology was developed at the MIT and licensed to

several corporations. The process is similar to the SLS process, but instead of using a laser to

sinter the material, an ink-jet printing head deposits a liquid adhesive that binds the material.

Material options are somewhat limited but are inexpensive relative to other additive

processes. 3D printing is quite fast, typically 2 –4 layers/minute. However, the accuracy,

surface finish, and part strength are not as good as some other additive processes. At the end

the part is infiltrated with a sealant to improve strength and surface finish.

Figure 5.5 3D Printers

Abbreviation: 3DP

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Material type: Powder

Materials: Ferrous metals such as Stainless steel; Non-ferrous metals such as Bronze; Elastomers; Composites; Ceramics

Min layer thickness: 0.05mm

Surface finish: Rough

Build speed: Very Fast

Applications: Concept models, Limited functional testing, Architectural& landscape models, Consumer goods& packaging

Table 5.5. Details for 3D printers

5.6 Direct Metal Laser Sintering (DMLS)

DMLS technology was developed jointly by Rapid Prototyping Innovations (RPI) and EOS

in 1994. It was the first commercial RP-method to produce metal parts in a single process.

Metal powder (20 μm diameter) without binder is completely melted by scanning of a high

power laser beam. The density of a produced part is about 98%. SLS has about 70%. One

advantage of DMLS compared to SLS is the small size of particles which enables very

detailed parts.

Abbreviation: DMLS

Material type: Powder(Metal)

Materials: Ferrous metals such as Steel alloys, Stainless steel, Tool steel; Aluminium, Bronze, Cobalt-chrome, Titanium, Ceramics..

Min layer thickness: 0.02mm

Surface finish: Average

Build speed: Fast

Applications: Form/fit testing, Functional testing, Rapid tooling, High heat applications, Medical implants, Aerospace parts..

Table 5.6 Details for Direct Metal Laser Sintering

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Figure 5.6 Direct Metal Laser Sintering

Chapter-6

PART DEPOSITION PLANNING

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A defect less STL file is used as an input to RP software like Quick Slice or RP-Tools for

further processing. At this stage, designer has to take an important decision about the part

deposition orientation. The part deposition orientation is important because part accuracy,

surface quality, building time, amount of support structures and hence cost of the part is

highly influenced. In this section various factors influencing accuracy of RP parts and part

deposition orientation are discussed as follows:-

6.1 Factors influencing accuracy

Accuracy of a model is influenced by the errors caused during tessellation and slicing at data

preparation stage. Decision of the designer about part deposition orientation also affects

accuracy of the model.

6.2 Errors due to tessellation:

In tessellation surfaces of a CAD model are approximated piecewise by using triangles. It is

true that by reducing the size of the triangles, the deviation between the actual surfaces and

approximated triangles can be reduced. In practice, resolution of the STL file is controlled by

a parameter namely chordal error or facet deviation. It has also been suggested that a curve

with small radius (r) should be tessellated if its radius is below a threshold radius (r o) which

can be considered as one tenth of the part size, to achieve a maximum chordal error of (r/r o).

Value of can be set equal to 0 for no improvement and 1 for maximum improvement.

6.3 Errors due to slicing:

Real error on slice plane is much more than that is felt. For a spherical model proposed that

error due to the replacement of a circular arc with stair-steps can be defined as radius of the

arc minus length up to the corresponding corner of the staircase, i.e., cusp height. Thus

maximum error (cusp height) results along z direction and is equal to slice thickness.

Therefore, cusp height approaches to maximum for surfaces, which are almost parallel with

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the x-y plane. Maximum value of cusp height is equal to slice thickness and can be reduced

by reducing it; however this results in drastic improvement in part building time.

Figure 6.3.1 Real error Slice Plane

Therefore, by using slices of variable thicknesses (popularly known as adaptive slicing), cusp

height can be controlled below a certain value.

Except this, mismatching of height and missing features are two other problems resulting

from the slicing. Although most of the RP systems have facility of slicing with uniform

thickness only, adaptive slicing scheme, which can slice a model with better accuracy and

surface finish without loosing important features must be selected.

Figure 6.3.2 Slicing of a ball, (a) No Slicing; (b) Thick Slicing; (c) Thin Slicing; (d)

Adaptive Slicing

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6.4 Part building:

During part deposition generally two types of errors are observed and are namely curing

errors and control errors. Curing errors are due to over or under curing with respect to curing

line and control errors are caused due to variation in layer thickness or scan position control.

Figure illustrates effect of over curing on part geometry and accuracy. Adjustment of

chamber temperature and laser power is needed for proper curing. Calibration of the system

becomes mandatory to minimize control errors. Shrinkage also causes dimensional

inaccuracy and is taken care by choosing proper scaling in x, y and z directions. Polymers are

also designed to have almost negligible shrinkage factors.

Figure 6.4. Over-curing effects on accuracy in Stereolithography

6.5 Part finishing:

Poor surface quality of RP parts is a major limitation and is primarily due to staircase

effect. Surface roughness can be controlled below a predefined threshold value by using an

adaptive slicing. Further, the situation can be improved by finding out a part deposition

orientation that gives minimum overall average part surface roughness. However, some RP

applications like exhibition models, tooling or master pattern for indirect tool production etc.

require additional finishing improving the surface appearance of the part. This is generally

carried by sanding and polishing RP models which leads to change in the mathematical

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definitions of the various features of the model. The model accuracy is mainly influenced by

two factors namely the varying amount of material removed by the finishing process and the

finishing technique adopted. A skilled operator is required as the amount of material to be

removed from different surfaces may be different and inaccuracies caused due to deposition

can be brought down. A finishing technique selection is important because different

processes have different degrees of dimensional control. For example models finished by

employing milling will have less influence on accuracy than those using manual wet sanding

or sand blasting.

6.6 Selection of part deposition orientation:

This is one of the crucial decisions taken before slicing the part and initiating the process of

deposition for a particular RP process. This decision is important because it has potential to

reduce part building time, amount of supports required, part quality in terms of surface finish

or accuracy and cost as well. Selection of part deposition orientation is process specific where

in designer and RP machine operators should consider number of different process specific

constraints. This may be a difficult and time consuming task as designer has to trade-off

among various conflicting objectives or process outcomes. For example better part surface

quality can be obtained but it will lead to increase in the building time.

Chapter-7

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MAJOR APPLICATIONS OF RAPID PROTOTYPING

Table 7.1 Applications of rapid prototyping

7.1 Automobiles:

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Different Alternative Inlet Manifolds were required to be built. Three major parts were made by laser sintering. By using the methodology, the time

for desktop to produce the product took about 10% of the time earlier.

Figure 7.1.1 Intake Manifold

The Audi RSQ was made with rapid prototyping industrial KUKA robots

Figure 7.1.2 The Audi RSQ 

7.2 Toy Industries:

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The performance of Formula One racing car can be tested by preparing a rapid prototype model with the help of wax modelling.

Figure 7.2.1 Formula One car prototype modelling

Similarly, toys made of plastics can be prepared through Rapid Prototyping.

Figure 7.2.2 Plastic model of a plane

7.3 Medicine:

Models of skull and other body structure can be used for training of medical surgical operation in various hospitals and medical institutions.

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Figure 7.3.1 Models of skull

Figure 7.3.2 Parts made of titanium are used for replacements

These Siamese twins were successfully separated. The operation was planned with the models of skull.

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Figure 7.3.3 RP Skull model used for planning brain surgery

7.4 Architecture:

To prepare a model of house or a terrain with the help of 3D modelling.

Figure 7.4 RP used for preparing architecture design

Chapter-8

ADVANTAGES AND LIMITATIONS

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The Rapid prototype that is developed by the process of rapid prototyping is based on the

performance of earlier designs. Hence, it is possible to correct the defects or problems in the

design by taking corrective measures. The product can be produced if the prototype meets the

requirements of all designing objectives after sufficient refinement. There are many

advantages of rapid prototyping.

8.1 ADVANTAGES:

Rapid Prototyping can provide with concept proof that would be required for attracting funds.

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

Rapid prototyping can enhance the early visibility.

It is easier to find the design flaws in the early developmental stages.

Active participation among the users and producer is encouraged by rapid prototyping.

As the development costs are reduced, Rapid prototyping proves to be cost effective.

The user can get a higher output.

The deficiencies in the earlier prototypes can be detected and rectified in time.

The speed of system development is increased. It is possible to get immediate feedback from the user.

There is better communication between the user and designer as the requirements and expectations are expressed in the beginning itself.

High quality product is easily delivered by way of Rapid prototyping.

Rapid prototyping enables development time and costs.

There are many innovative ways in which Rapid prototyping can be used.

8.2 LIMITATIONS:

It could so happen that some important developmental steps could be omitted to get a quick and cheap working model. This can be one of the

greatest disadvantages of rapid prototyping.

Another disadvantage of rapid prototyping is one in which many problems are overlooked resulting in endless rectifications and revisions

One more disadvantage of rapid prototyping is that it may not be suitable for large sized applications.

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The user may have high expectations about the prototype’s performance and the designer is unable to deliver it.

The system could be left unfinished due to various reasons or the system may be implemented before it is completely ready.

The producer may produce an inadequate system that is unable to meet the overall demands of the organization.

Too much involvement of the user might hamper the optimization of the program.

The producer may be too attached to the program of prototyping, thus it may lead to legal involvement.

The cost reduction benefit of rapid prototyping also seems to be dabatable, as sufficient details regarding the calculation basis and assumptions are

not substantial.

Chapter-9

THE FUTURE OF 3-D PRINTING

Rapid Prototyping is moving in several directions at this time and all indications are that it

will continue to expand in many areas in the future. Some of the most promising areas

include medical applications, custom parts replacement, and customized consumer products.

As materials improve and costs go down, other applications we can barely imagine today will

become possible.

Perhaps the greatest area of potential growth for rapid prototyping is in the medical field. As

mentioned above, researchers are just starting to experiment with the idea of creating

artificial bones with rapid prototyping, but the process could potentially be used for so much

more. Some companies are investigating the possibility of printing organic materials; these

materials could be used in a much wider array of surgeries and potentially replace a much

larger selection of defective human parts. Expect expansion of training techniques based on

rapid prototyping models of complex human systems, a greater effort to more explicitly

explain surgeries or the workings of the human body to patients as detailed replicas of body

parts to become more common, and more precise surgical and diagnostic equipment based on

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designs that can be printed but not manufactured using traditional means.

Another area of growth in the rapid prototyping arena is replacement parts production. If we

need a new screw for our laptop or a new gear for our heirloom grandfather clock, or a new

piston for our car, then instead of trying to track down the part, pay for shipping, and waiting

weeks for its arrival, we'll just be able to print it out and go. Mechanics will keep specs for

every part of every car ever sold in a database and print out whatever they need immediately

with no difficulty. While it would save time and money for any part, it's a particular boon for

restoration jobs of all kinds where the original parts are extremely difficult to find or may not

even exist anymore.

Rapid prototyping can also used in the elite design and engineering schools to teach students

the practical side of their course of study. And with the advent of low cost technologies like

ours, students in middle school and high school will also be able to learn the complex

principles in STEM (science, technology, engineering, and math).

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Table 9.1 The result of introduction of RP in design cycle

Chapter-9

CONCLUSION

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RP is a technology that can be used for many different applications, both manufacturing and

non-manufacturing based. It can enhance and optimize the product development process.

Whilst there are still many outstanding technological issues surrounding development and

application of RP technology, it has already proved that it can be a valuable addition to the

range of automated systems available to manufacturers.

It can be concluded that RP has made a good introduction and has a bright future in making

PD more effective and efficient. Rapid Tooling assists this in current applications, but one

should maintain a watching brief on the development of the exciting area of Rapid

Manufacturing, which is ultimately set to revolutionize the way we manufacture products to

meet the demands of modern consumers.

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