“PAANI GENIE – AN IMPROVED WATER

COLLECTION DEVICE”

A PROJECT REPORT

Submitted byJay Puducheri 1021210349Fajal Ashraf 1021210346Tirthankar Bhattacharjee 1021210374

Under the guidance ofMr. K.V. SREEJITH,

Assistant ProfessorDepartment of Mechanical Engineering

in partial fulfillment for the award of the degreeof

BACHELOR OF TECHNOLOGY

inMECHANICAL ENGINEERING

of

FACULTY OF ENGINEERING & TECHNOLOGY

S.R.M. Nagar, Kattankulathur, Kancheepuram District

APRIL 2016

i

SRM UNIVERSITY(Under Section 3 of UGC Act, 1956)

BONAFIDE CERTIFICATE

Certified that this project report titled “PAANI GENIE” is the bonafide work

of “Jay Puducheri ,Fajal Ashraf , Tirthankar Bhattacharjee ”, who

carried out the project work under my supervision. Certified further, that to the best of

my knowledge the work reported herein does not form any other project report or

dissertation on the basis of which a degree or award was conferred on an earlier

occasion on this or any other candidate.

SIGNATURE SIGNATURE

GUIDE HEAD OF THE DEPARTMENT MR. K.V. SREEJITH MECHANICAL ENGINEERING

Signature of the Internal Examiner Signature of the External Examiner

ii

iii

TABLE OF CONTENTS

CHAPTER No.

TITLE PAGE NO

ABSTRACT vACKNOWLEDGEMENT viLIST OF TABLES viiLIST OF FIGURES vii

1. INTRODUCTION 11.1 GENERAL 11.2 WATER CRISIS 11.3 EFFECTIVE AND EFFICIENT 3

2. LITERATURE SURVEY 4

3. 3.1 GENERAL3.2 PRODUCTION PROCESS

610

3.1.1 ROTATIONAL MOLDING PROCESS

11

3.1.2 RECENT IMPROVEMENTS 123.1.3 TYPICAL MOLDING APPLICATION

12

3.2 MOLD RELEASE AGENTS 133.3 MATERIALS 133.4 PRODUCTS 143.5 DESIGN CONSIDERATION 143.5.1 PRODUCT DESIGN FOR ROTATIONAL MOLDING

14

3.5.2 DESIGN 153.6 PROCESS : ADVANTAGES, LIMITATIONS AND MATERIAL REQUIREMENTS

15

3.6.1 ADVANTAGES 163.6.2 LIMITATIONS 173.6.3 MATERIAL REQUIREMENTS 183.6.4 CLAIMED BENEFITS 183.7 WALL THICKNESS 193.8 RESIN CHOICE 193.9 MELT INDEX 203.10 TYPES OF POLYETHYLENE 22

iv

3.11 MOULDS FOR ROTATIONAL MOLDING

23

3.12 TYPES OF MOULDS 233.12.1 FLANGE-MEETING, SURFACES AND HINGES

23

3.12.2 MOULD MOUNTING 243.12.3 INSULATION LIDS AND COVERINGS

24

3.12.4 VENTING 253.12.5 MOULD RELEASE 253.13 ROTOMOULDING EQUIPMENT

25

3.13.1 HEATING STATIONS 263.13.2 MOULD COOLING STATIONS 263.13.3 INSTRUMENTATION 263.13.4 FINISHING ROTATIONALY MOULDED PIECES3.14 TESTING PROCESS OF THE

PRODUCT

26

28

4. 4.1 CONCLUSION 314.1.1 FUTURE ENHANCEMENT 31

5. APPENDICES 33

6. REFERENCES 34

v

ABSTRACT

The Paani Genie the most efficient and appropriate technology to achieve

this purpose. Instead of being carried on the head, the weight of the water

remains on the ground in a drum. A steel clip-on handle allows the wo-

men and children to roll the drum by either pushing or pulling it, depend-

ing on gradients. Compared to a bucket, the Panni Genie allows 5 times

more water to be carried home. As an additional benefit, it saves time and

while women can use it for other household tasks, children can attend

school more often, resulting in better education. Basic hygiene and health

can be significantly improved and long-term injuries from carrying heavy

weights are prevented. The durable design ensures a lifespan of 5 to 7

years and often even longer, depending on prevailing conditions. The

maintenance-free design and no consumable parts, ensures sustainability

and long-term success in remote locations.

The manufactured product was a rotomoulded HDPE water roller carry-

ing 90 litres of water. The HDPE material was chosen due to its impact,

and wear resistant, flexible, can have very high elongation before break-

ing, generally good chemical resistance, food contact grade. This product

was then tested and distributed to various remote locations.

vi

ACKNOWLEDGEMENT

We would like to acknowledge the help of a few in our journey. Akhil

Nichani, Maanasa Madhu Krishna, Achintya Bansal, Shantanu Vyas, Hiroshan G and

Trishanka Menon who are all part of the Paani Genie team. Mukesh Ambani and IN-

FRA, our manufacturers who have helped us bring this product to life. Vinod Saraogi

and the Rotary Club for providing us with their resources to find suitable villages to

pilot this project in. All of our generous donors. Lady Andal Venkatasubba Rao

School where 6 of the 7 Moving Forward members studied has shown us great sup-

port and encouragement. Mr. Jayaprakash and Dr. Sharma for early advice and guid-

ance with respect to producing Paani Genie and for connecting us with Infra. The

Hindu, Chennai Live 104.8 and other media agencies who have given us much appre-

ciated exposure. Bhaskar, a junior level Panachayat official in Vinayaganallur who

has been our contact in the village and has helped us co-ordinate with the vil-

lagers. Mr. Sreejith, Dr. Haridasan for guiding us through this entire process.

vii

LIST OF TABLES

TABLE No. Name Page No.

3.9 An increase in Melt Index and Density 20

6.2 Table 3.3 Test Results from CIPET 22

6.3 Tensile Strength for Isopthalic. 24

6.4 Flexural Test for Polyester. 27

LIST OF FIGURES

TABLE No. Name Page No.

2.1 Mould 11

3.1 Finished Product 27

3.2 Lid 27

viii

CHAPTER 1

INTRODUCTION

1.1 GENERAL

The Paani Genie, is a device for carrying water more easily and efficiently

than traditional methods, particularly in the developing world. It consists of a barrel-

shaped container which holds the water and can roll along the ground, and a handle

attached to the axis of the barrel. It’s simple and purpose-built nature makes it an

example of appropriate technology. This project aims to alleviate the daily struggle

endured by women and children in rural India by helping them improve their ability to

transport more water, in less time with considerable ease. Paani Genie is a water roller

that has a capacity of 90 litres, which is five times that of the normal pot being used. It

has many advantages, which include saving time, energy and reducing suffering. It is

also environment friendly, as the wide rolling surface helps compact soil to minimise

erosion unlike narrow wheelbarrows. Another interesting application of Paani Genie

is that once it is damaged beyond its usefulness for water collection, it can be used as

a storage bin and when cut vertically in half, or as a feeding/water trough for animals

and a bath for washing clothes and children. This project is one that will substantially

increase the quality of life of people in rural India. Partner with us and help

underdeveloped communities improve their access to water for immediate benefits

and tangible results.

1.2 WATER CRISIS

There is an urgent need for the Paani Genie because it offers an immediate

solution to the relentless struggle to collect enough water for daily activities,

consumption and sustenance farming and results in improvements to health and living

standards. According to the United Nations, this affects approximately 1 billion

people who are without adequate access to water. The statistics on access to water

does not reflect the reality on the ground, where many people struggle to live a

dignified life. While the Paani Genie is not a permanent water solution, it does offer

an immediate and appropriate response to the issues surrounding water access and

1

food security. With respect to our pilot village, we had three criteria that we wanted

our village to satisfy:

1) It must have a significant water problem with people walking at least 1.5

kilometres for their water.

2) The village must not have more than 150 homes. As this is our first project,

we want to start small.

3) The village must be within a three hour radius of Chennai. As this project is

run by a group of college students, we would find it hard to visit a village on a

regular basis if it were very far away. We wanted to find a village that we

could visit on a relatively regular basis so that we could develop a relationship

with the people in the village.

After visiting between 15 and 20 villages, we found Vinayaganallur, a village two and

a half hours away from Chennai with 125 homes. People walk 2 kilometres and more

to get their water between April and September. Vinayaganallur satisfied all of our

criteria and so has been selected as our pilot village.

Vinayaganallur is located in Kancheepuram district, 10 minutes away from Vedan-

thangal bird sanctuary. We contacted the Rotary Club and asked them to help us find

a village to pilot this project. With their assistance, we visited over 15 villages in

Tamil Nadu over a span of 4 months hoping to find the ideal village. In our head, the

ideal village is one where: 

1. There are 100-150 homes. This is in our size bracket.

2. People walk a minimum of 1.5 kilometers to reach the water source. 

3. The village should not be further than 2 hours from Chennai. Most of the

Paani Genie team comprises of college students studying in Chennai and so

accessibility to the village where the project is being piloted is crucial. 

After looking at many villages in areas like Jolarpet and Vellore, we happened

to connect with a Rotary member who invited us to take a look at Vinayaganallur. We

visited Vinayaganallur in January 2015 and were instantly struck by how aptly it met

2

all of our base conditions. It has 120 homes and is located an hour and forty five min-

utes away from Chennai. Vinayaganallur is located in a rectangle comprising of ten

villages. All the villages are similar to Vinayagallur. When water is in short supply,

the people of these 10 villages walk from village to village in search of a water source

that has not been exhausted. If the people of Vinayaganallur are lucky, the first village

on their walk will have a working water source and this is at a distance of 1.5 km

from their homes. If the first village does not have a working water source, they con-

tinue walking from village to village until they find one that works. In the worst case

scenario, they end up walking close to 5 kilometers. This ridiculous dependence on

luck for the people of these villages hit home hard with all the Paani Genie team

members and we decided to adopt Vinayagallur as the pilot village. We visit Vinaya-

ganallur once in two weeks and have established a good relationship with the people

who live there. Gaining their trust is important as we gear up to helping them make

the step up from using 15 liter crippling Kodams to 90 liter Paani Genies that make

your life easy. 

1.3 EFFECTIVE & EFFICIENT

Our innovation makes more water and time available for education, household

tasks and food production as smallholder farmers can transport up to 5 x more water

to their homes and food gardens. Currently, they tend to rely on traditional methods of

water collection that consume excessive amounts of energy and time, which could be

better spent on food production and school attendance to break free from the poverty

cycle. The Hippo roller is very user friendly for women, children and physically weak

as it makes the transportation of water much less strenuous than traditional methods.

It is specifically designed for rural and economically poor communities with its low to

none maintenance costs and there is no need to access spare parts which is very

difficult in these areas.

3

CHAPTER 2

LITERATURE SURVEY

1. Social Impact of the Hippo Water Roller, retrieved 02 November 2015 - The

Hippo water roller, or Hippo roller, is a device for carrying water more easily and

efficiently than traditional methods, particularly in the developing world. It con-

sists of a barrel-shaped container which holds the water and can roll along the

ground, and a handle attached to the axis of the barrel. Currently deployed in rural

Africa, its simple and purpose-built nature makes it an example of appropriate

technology.

2. Ward, Noel M. (Winter 1997). "A History of Rotational Moulding". Platiquarian

Reprints - Rotational Molding (BrE moulding) involves a heated hollow mold

which is filled with a charge or shot weight of material. It is then slowly rotated

(usually around two perpendicular axes) causing the softened material to disperse

and stick to the walls of the mold. In order to maintain even thickness throughout

the part, the mold continues to rotate at all times during the heating phase and to

avoid sagging or deformation also during the cooling phase. The process was ap-

plied to plastics in the 1940s but in the early years was little used because it was a

slow process restricted to a small number of plastics. Over the past two decades,

improvements in process control and developments with plastic powders have res-

ulted in a significant increase in usage. Rotocasting (also known as rotacasting),

by comparison, uses self-curing resins in an unheated mould, but shares slow rota-

tional speeds in common with rotational molding.

3. Beall, Glenn (1998), Rotational Molding, Hanser Gardner Publications, The

rotational molding process is a high-temperature, low-pressure plastic-forming

process that uses heat and biaxial rotation (i.e., angular rotation on two axes) to

produce hollow, one-piece parts. Critics of the process point to its long cycle

times—only one or two cycles an hour can typically occur, as opposed to other

processes such as injection molding, where parts can be made in a few seconds.

The process does have distinct advantages. Manufacturing large, hollow parts

4

such as oil tanks is much easier by rotational molding than any other method.

Rotational molds are significantly cheaper than other types of mold. Very little

material is wasted using this process, and excess material can often be re-used,

making it a very economically and environmentally viable manufacturing process.

4. Crawford, R, Throne, James L., Rotational Moulding of Plastics, William Andrew

Size – Rotational molded products can be as small as a ping pong ball and as large

as a 20,000 gallon tanks. Dutchland Plastics is capable of manufacturing products

from 0 to 1000 pounds in weight and up to 17 feet long.

Design –Rotational molding allows much more flexibility in product design

compared to blow molding. Complex shapes and moving sections are easier to

manufacture and rotomolding offers a distinct advantage with uniform wall

thickness.

5

CHAPTER 3

3.1 GENERAL

The production of Paani Genie water roller was done by rotational molding

process. This process was chosen because of various reasons explained below, but

here we will explain briefly. The water roller is a 50 X 50 X 65 cm hollow drum, it

has a detachable rod handle; 100 X 70 X 3 cm, the opening diameter was designed to

be at 135 mm or 53 inches. This was done so that the opening extractions on the

finished product doesn’t affect the smooth rolling of the water roller. The detachable

rod enables the push and pull activity easily for most humans by just varying the

angle to the roller. The size of the rod make is very easy to handle and easily attach

and detach it from the roller. The usability of the rod was used to base the design

interpretations of it into the water roller. The water roller needed to be of the specific

height, diameter and width to meet the design requirements for the volume

specification, which needed the water roller to carry 90 liters. So the Paani Genie

water roller has a 90 liter water carrying capacity. Rotational molding process was

chosen as they had many advantages compared to other plastic molding process

methods. Most manufacturers of hollow type plastics usually prefer this the most in

producing their products. Other terms used to refer to the process are roto-molding

and roto-casting. Slush molding is also used in liquid-vinyl which is also a similar

process. Rotational molding has several benefits attached to it and some of the major

ones include; low residual-stresses levels and cheaper molds. They are:

Size options: The process fits any size from the tiniest to larger sizes; this

means that there is a room for flexibility as compared to other systems. The

rotational molding can be done on a small Ping-Pong sized plastic to even

21,000 gallon-tanks. Many manufacturers of the moldings are able to make a

gallon of between 0 to 1000 pounds and as high as 17ft. This is a big

6

advantage since different sizes can be manufactured using the process, in this

aspect the molding can make many sizes to be used for many purposes.

Different designs: It’s very easy to design many shapes using the rotational

molding process; this is due to the fact that when the hot plastic or compounds

are put into a mold, they will take the shape of the mold, which makes it ideal

for creativity since any shape can be made from the process. Other types of

molding processes are rigid in nature with few options, but the rotational

molding can provide a lot of variety in the manufacturing phase. Also to keep

in mind is that there is more room for designing in the process when compared

to the blow molding method. Rotational molding can be used to manufacture

many complex designs and shapes especially moving sections. Besides it has

uniform-thickness of its walls, which is a distinct advantage in designing

different shapes.

Inserts: The rotational moulding process can easily accept metal inserts while

producing the product and it also allows the possibility for additional

threading inserts. All these can be processed at very low costs, as compared to

other methods which are cumbersome. Assembly’s techniques can be easily

altered in the rotomoulding process, which offers the aspect of lower costs and

durability in all dimensions.

Color sectioning: Color sectioning is much easier with this rotomold process

and the color-blending can be done in-house to a variety of shades. The color

matching is easily done on the rotational molding without extreme volumes;

any pattern imaginable can be created with this process. There are a number of

colors which can be achieved and at a lower cost. Some of the colors which

are available include; sandstone, marble and other color varieties.

Quality surface finishing: The process offers high quality surface finishing

capabilities by exactly taking the shape of the particular mold plus the texture.

This makes room for very high gloss quality finishes on the product surface. It

also can reflect smoothness and quality artistic product design and take on a

high oriental texture finish on its surface.

Decorations in mold: The rotomolding process takes any authentically

designed decorations which are made in the mold and will feature it on the

plastic in a vibrant manner. The in-mold techniques used to decorate and

7

design graphics are a by-product of the rotational molding process. The unique

design of graphics will stick permanently in the final rotational plastic product.

This method makes it possible for items like serial numbers, bar-codes and

colorful logos to be molded easily. They often appear and are better quality as

opposed to the traditional ones.

Quick tooling: Among the advantages of rotational moulding is the process of

quick tooling. The reason is, the process is slow-pressure without any need of

ejection or in-mold cooling. The cast aluminum manufactured molds are very

easy to use especially when cooling. The tooling process offers less expenses

when aluminum is involved. A new tooling-process takes about 4 to 10 weeks

depending on the design and complexity involved. Multiple molds are also

manufactured easily by aluminum casts. The actual fact is that the other

molding processes like the blow-molding and others can be expensive and

complicated. For variety of designs and even graphics, rotational molding has

an upper hand. Bottom line is that with the advantages of rotational molding

you get a much easier process with versatility and more cost savings.

The Paani Genie water roller’s material was selected to be HDPE, (High Density

Polyethylene). This thermoplastic is available in a range of flexibilities depending on

the production process. High density materials are the most rigid. The polymer can be

formed by a wide variety of thermoplastic processing methods and is particularly

useful where moisture resistance and low cost are required. Polyethylene is limited by

a rather low temperature capability (200-250 F) but is manufactured in billions of

pounds per year. Vinyl acetate can be copolymerized with ethylene. The resulting

product has improved transparency over homopolymerized polyethylene because of a

reduction of crystallinity in the copolymer.

Basic Advantages of HDPE over other plastics:

• Low cost

• Impact resistant from -40 C to 90 C

• Moisture resistance

• Good chemical resistance8

• Food grades available

• Readily processed by all thermoplastic methods

Basic Disadvantages

• High thermal expansion

• Poor weathering resistance

• Difficult to bond

• Flammable

In general, high density grades of polyethylene have densities up to 0.97 g/cm^. Low

density grades are as low as 0.91 g/cm^. Typically, the high-density material is more

linear and consequently more crystalline. As might be expected, this higher

crystallinity permits use at temperatures up to 130 C with somewhat better creep

resistance below that temperature. Low density polyethylene has less stiffness than

the high density type. Blends of the two types are common. With a high strength-to-

density ratio, HDPE is used in the production of plastic bottles, corrosion-resistant

piping, geomembranes, and plastic lumber. HDPE plastic has several properties that

make it ideal as a packaging and manufacturing product. It’s stronger than standard

polyethylene, acts as an effective barrier against moisture and remains solid at room

temperature. It resists insects, rot and other chemicals. HDPE creates no harmful

emissions during its production or during its use by the consumer. Also, HDPE leaks

no toxic chemicals into the soil or water. It works well in extreme hot or cold with a

temperature range from -100 to 120 degrees Celsius. This material has a tensile

strength of 4550 pounds per square inch. HDPE gets harder and stiffer as the

temperature drops, but does not get brittle like other plastics. HDPE is resistant to

many dilute and concentrated solvents containing acids, bases, or alcohol. HDPE is

Rot resistant, Remains cool to the touch in high temperatures unlike metal core trays

and its structural integrity is unaffected by UV rays.

9

3.2 PRODUTION PROCESS

The rotational molding process is a high-temperature, low-pressure plastic-

forming process that uses heat and biaxial rotation (i.e., angular rotation on two axes)

to produce hollow, one-piece parts. Critics of the process point to its long cycle times

—only one or two cycles an hour can typically occur, as opposed to other processes

such as injection molding, where parts can be made in a few seconds. The process

does have distinct advantages. Manufacturing large, hollow parts such as oil tanks is

much easier by rotational molding than any other method. Rotational molds are

significantly cheaper than other types of mold. Very little material is wasted using this

process, and excess material can often be re-used, making it a very economically and

environmentally viable manufacturing process. Until recently, the process was largely

empirical, relying on both trial and error and the experience of the operator to judge

when the part should be removed from the oven, and when it was cool enough to be

removed from the mold. Technology has improved in recent years, allowing the air

temperature in the mold to be monitored, removing much of the guesswork from the

process.

Much of the current research is into reducing the cycle time, as well as

improving part quality. The most promising area is in mold pressurization. It is well

known that applying a small amount of pressure internally to the mold at the correct

point in the heating phase accelerates coalescence of the polymer particles during the

melting, producing a part with fewer bubbles in less time than at atmospheric

pressure. This pressure delays the separation of the part from the mold wall due to

shrinkage during the cooling phase, aiding cooling of the part. The main drawback to

this is the danger to the operator of explosion of a pressurized part. This has prevented

adoption of mold pressurization on a large scale by rotomolding manufacturers.

10

Figure 2 : Mould

3.2.1 ROTATIONAL MOULDING PROCESS

The rotational moulding process consists of four distinct phases:

1. Loading a measured quantity of polymer (usually in powder form) into the

mold.

2. Heating the mold in an oven while it rotates, until all the polymer has melted and

adhered to the mold wall. The hollow part should be rotated through two or more

axes, rotating at different speeds, in order to avoid the accumulation of polymer

powder. The length of time the mold spends in the oven is critical: too long and

the polymer will degrade, reducing impact strength. If the mold spends too little

time in the oven, the polymer melt may be incomplete. The polymer grains will

not have time to fully melt and coalesce on the mold wall, resulting in large bub-

bles in the polymer. This has an adverse effect on the mechanical properties of

the finished product.

3. Cooling the mold, usually by fan. This stage of the cycle can be quite lengthy.

The polymer must be cooled so that it solidifies and can be handled safely by the

operator. This typically takes tens of minutes. The part will shrink on cooling,

coming away from the mold, and facilitating easy removal of the part. The cool-

ing rate must be kept within a certain range. Very rapid cooling (for example, wa-

ter spray) would result in cooling and shrinking at an uncontrolled rate, producing

a warped part.

11

4. Removal of the part.

3.1.2 RECENT IMPROVEMENTS

Until recently, the process was largely empirical, relying on both trial and er-

ror and the experience of the operator to judge when the part should be removed from

the oven, and when it was cool enough to be removed from the mould. Technology

has improved in recent years, allowing the air temperature in the mould to be mon-

itored, removing much of the guesswork from the process.

Much of the current research is into reducing the cycle time, as well as im-

proving part quality. The most promising area is in mould pressurization. It is well

known that applying a small amount of pressure internally to the mould at the correct

point in the heating phase accelerates coalescence of the polymer particles during the

melting, producing a part with fewer bubbles in less time than at atmospheric pres-

sure. This pressure delays the separation of the part from the mould wall due to

shrinkage during the cooling phase, aiding cooling of the part. The main drawback to

this is the danger to the operator of explosion of a pressurized part. This has prevented

adoption of mould pressurization on a large scale by rotomolding manufacturers.

3.1.2 TYPICAL ROTOMOULDING APPLICATIONS

Rotational molding permits production of a countless number of fully or

partially closed items. Design versatility of rotationally molded pieces is almost

unlimited. The rigidity or flexibility of an item is controlled by the properties of the

resin used (see section on Resin Choice) and by the wall thickness of the molding.

Some typical applications for which rotational molding is particularly suited include

the following:

• Commercial, industrial and agricultural storage tanks ranging in size from 5

gallons to 22,000 gallons;

• Containers for packaging and material handling;

• A variety of industrial parts, especially covers and housings, water softening

tanks, tote bins;

12

• Numerous under-the-hood and in-the-cab automotive parts

Rotomolded parts are also used in portable outhouses, battery cases, light

globes, vacuum cleaner and scrubber housings and garbage containers. Furniture,

game housings, surf boards, traffic barricades, display cases and ducting can also be

produced by rotomolding. The list above indicates just some of the possibilities.

3.2 MOULD RELEASE AGENTS

A good mold release agent (MRA) will allow the material to be removed

quickly and effectively. Mold releases can reduce cycle times, defects, and browning

of finished product. There are a number of mold release types available; they can be

categorized as follows:

Sacrificial coatings: the coating of MRA has to be applied each time because most

of the MRA comes off on the molded part when it releases from the tool. Silicones

are typical MRA compounds in this category.

Semi-permanent coatings: the coating, if applied correctly, will last for a number

of releases before requiring to be re-applied or touched up. This type of coating is

most prevalent in today's rotational molding industry. The active chemistry in-

volved in these coatings is typically a polysiloxane.

Permanent coatings: most often some form of PTFE coating, which is applied to

the mold. Permanent coatings avoid the need for operator application, but may be-

come damaged by misuse.

3.3 MATERIALS

More than 80% of all the material used is from the polyethylene family: cross-

linked polyethylene (PEX), low-density polyethylene (LDPE), linear low-density

polyethylene (LLDPE), high-density polyethylene (HDPE), and regrind. Other com-

pounds are PVC plastisol’s, nylons, and polypropylene.

13

3.4 PRODUCTS

Designers can select the best material for their application, including materials

that meet U.S. Food and Drug Administration (FDA) requirements. Additives for

weather resistance, flame retardation, or static elimination can be incorporated. In-

serts, graphics, threads, handles, minor undercuts, flat surfaces without draft angles,

or fine surface detail can be part of the design. Designs can also be multi-wall, either

hollow or foam filled.

Products that can be manufactured using rotational moulding include storage

tanks, furniture, road signs and bollards, planters, pet houses, toys, bins and refuse

containers, doll parts, road cones, footballs, helmets, canoes, rowing boats, kayak

hulls and playground slides. The process is also used to make highly specialised

products, including UN-approved containers for the transportation of nuclear fissile

materials, anti-piracy ship protectors, seals for inflatable oxygen masks and light-

weight components for the aerospace industry.

3.5 DESIGN CONSIDERATION

3.5.1 Product design for rotational molding

There are many considerations for a designer when designing a part. Which

factors are most important to a client? For instance, a part may need to be cheap and a

certain colour. However, if another colour is cheaper, would the client be willing to

change colours? Designers are responsible for considering all the limitations and be-

nefits of using certain plastics. This may result in a new process being decided upon.

Another consideration is in the draft angles. These are required to remove the

piece from the mould. On the outside walls, a draft angle of 1° may work (assuming

no rough surface or holes). On inside walls, such as the inside of a boat hull, a draft

angle of 5° may be required, this is due to shrinkage and possible part warping.

Another consideration is of structural support ribs. While solid ribs may be de-

sirable and achievable in injection moulding and other processes, a hollow rib is the

best solution in rotational moulding. A solid rib may be achieved through inserting a

finished piece in the mould but this adds cost.

14

Rotational moulding excels at producing hollow parts. However, care must be

taken when this is done. When the depth of the recess is greater than the width there

may be problems with even heating and cooling. Additionally, enough room must be

left between the parallel walls to allow for the melt-flow to properly move throughout

the mould. Otherwise webbing may occur. A desirable parallel wall scenario would

have a gap at least three times the nominal wall thickness, with five times the nominal

wall thickness being optimal. Sharp corners for parallel walls must also be considered.

With angles of less than 45° bridging, webbing, and voids may occur.

3.5.2 DESIGN

With rotomolding, a plastics product designer can create a huge array of

innovative products. Typical design concerns that are handled routinely by rotational

molding include the following:

• maintaining uniform wall thickness – rotational molding can provide a more

consistently uniform wall thickness for a part compared to other plastic

processing methods;

• producing double-wall construction – rotational molding can provide uniform

double-wall construction on parts;

• Molding thicker corners – due to the process, rotomolded parts will have

thicker outer corners which help strengthen the parts;

• molding inserts, reinforcing ribs, kiss-off ribbing and undercuts these are

easily included in a roto-molded part.

3.6 PROCESS: ADVANTAGES, LIMITATIONS, AND MATERIAL

REQUIREMENTS

Another consideration is the melt-flow of materials. Certain materials, such as

nylon, will require larger radii than other materials. Additionally, the stiffness of the

set material may be a factor. More structural and strengthening measures may be re-

quired when a flimsy material is used.

15

3.6.1 ADVANTAGES

Rotational moulding offers design advantages over other moulding processes.

With proper design, parts assembled from several pieces can be moulded as one part,

eliminating high fabrication costs. The process also has inherent design strengths,

such as consistent wall thickness and strong outside corners that are virtually stress

free. For additional strength, reinforcing ribs can be designed into the part. Along with

being designed into the part, they can be added to the mould.

The ability to add prefinished pieces to the mould alone is a large advantage.

Metal threads, internal pipes and structures, and even different coloured plastics can

all be added to the mould prior to the addition of plastic pellets. However, care must

be taken to ensure that minimal shrinkage while cooling will not damage the part.

This shrinking allows for mild undercuts and negates the need for ejection mechan-

isms.

In some cases rotational moulding can be used as a feasible alternative to blow

moulding, this is due to the similarity in product outputs, with products such as plastic

bottles and cylindrical containers, this is only effective on a smaller scale as it much

more costly to blow mould regarding a small output, and with fewer resulting

products rotational molding is much cheaper, due to blow moulding relying on eco-

nomies of scale regarding efficiency.

Another advantage lies in the molds themselves. Since they require less tool-

ing, they can be manufactured and put into production much more quickly than other

molding processes. This is especially true for complex parts, which may require large

amounts of tooling for other molding processes. Rotational molding is also the desired

process for short runs and rush deliveries. The molds can be swapped quickly or dif-

ferent colours can be used without purging the mold. With other processes, purging

may be required to swap colours.

Due to the uniform thicknesses achieved, large stretched sections are non-ex-

istent, which makes large thin panels possible (although warping may occur). Also,

there is little flow of plastic (stretching) but rather a placing of the material within the

part. These thin walls also limit cost and production time.

16

Another cost limiting factor is the amount of material wasted in production.

There are no sprues or runners (as in injection molding), no off-cuts (thermoforming),

or pinch off scrap (blow molding). What material is wasted, through scrap or failed

part testing, can usually be recycled.

3.6.2 LIMITATIONS

Rotationally molded parts have to follow some restrictions that are different

from other plastic processes. As it is a low pressure process, sometimes designers face

hard to reach areas in the mold. Good quality powder may help overcome some situ-

ations, but usually the designers have to keep in mind that it is not possible to make

sharp threads that would be possible with injection molding. Some products based on

polyethylene can be put in the mold before filling it with the main material. This can

help to avoid holes that otherwise would appear in some areas. This could also be

achieved using molds with movable sections.

Another limitation lies in the molds themselves. Unlike other processes where

only the product needs to be cooled before being removed, with rotational molding

the entire mold must be cooled. While water cooling processes are possible, there is

still a significant down time of the mold. Additionally, this increases both financial

and environmental costs. Some plastics will degrade with the long heating cycles or in

the process of turning them into a powder to be melted.

The stages of heating and cooling involve transfer of heat first from the hot

medium to the polymer material and next from it to the cooling environment. In both

cases, the process of heat transfer occurs in an unsteady regime; therefore, its kinetics

attracts the greatest interest in considering these steps. In the heating stage, the heat

taken from the hot gas is absorbed both by the mold and the polymer material. The rig

for rotational molding usually has a relatively small wall thickness and is manufac-

tured from metals with a high thermal conductivity (aluminium, steel). As a rule, the

mold transfers much more heat than plastic can absorb; therefore, the mold temperat-

ure must vary linearly. The rotational velocity in rotational molding is rather low (4 to

20 rpm). As a result, in the first stages of the heating cycle, the charged material re-

mains as a powder layer at the bottom of the mold. The most convenient way of chan-

ging the cycle is by applying PU sheets in hot rolled forms.

17

3.6.3 MATERIAL REQUIREMENTS

Due to the nature of the process, materials selection must take into account the

following:

Due to high temperatures within the mold the plastic must have a high resistance

to permanent change in properties caused by heat (high thermal stability).

The molten plastic will come into contact with the oxygen inside the mold—this

can potentially lead to oxidation of the melted plastic and deterioration of the ma-

terial's properties. Therefore, the chosen plastic must have a sufficient amount of

antioxidant molecules to prevent such degradation in its liquid state.

Because there is no pressure to push the plastic into the mold, the chosen plastic

must be able to flow easily through the cavities of the mold. The parts design must

also take into account the flow characteristics of the particular plastic chosen.

3.6.4 CLAIMED BENEFITS

It is claimed that approximately five times the amount of water can be trans-

ported in less time with far less effort than the traditional method of carrying 20 litres

(approximately 5 gallons) on the head.

time savings (fetching water can be very time consuming in some poor rural

environments);

reduced effort;

reduced strain (carrying heavy weights on the head every day for years puts

strain on the body, particularly the vertebral column);

increased water availability, with benefits for health and perhaps even en-

abling vegetables to be grown

Hygienic storage due to the sealed lid on the roller.

18

3.7 WALL THICKNESS

One benefit of rotational molding is the ability to experiment, particularly with

wall thicknesses. Cost is entirely dependent on wall thickness, with thicker walls be-

ing costlier and more time consuming to produce. While the wall thickness can be

nearly any thickness, designers must remember that the thicker the wall, the more ma-

terial and time will be required, increasing costs. In some cases, the plastics may sig-

nificantly degrade due to extended periods at high temperature. Also, different materi-

als have different thermal conductivity, meaning they require different times in the

heating chamber and cooling chamber. Ideally, the part will be tested to use the min-

imum thickness required for the application. This minimum will then be established

as a nominal thickness.

For the designer, while variable thicknesses are possible, a process called stop

rotation is required. This process is limited in that only one side of the mold may be

thicker than the others. After the mould is rotated and all the surfaces are sufficiently

coated with the melt-flow, the rotation stops and the melt-flow is allowed to pool at

the bottom of the mold cavity.

Wall thickness is important for corner radii as well. Large outside radii are

preferable to small radii. Large inside radii are also preferable to small inside radii.

This allows for a more even flow of material and a more even wall thickness. How-

ever, an outside corner is generally stronger than an inside corner.

3.8 RESIN CHOICE

To obtain the desired end product, the choice of a quality powdered resin is

essential in rotational molding. One reason is the high temperatures used risk

chemical degradation in a less-than-quality product. Today, approximately 84 percent

of all resin used in rotational molding is polyethylene.

While the effects of particle size on end-product properties and process ability

are less critical, those of melt index and density are considerable.

19

3.9 MELT INDEX

For rotomolding, a resin must have a good flow when molten. With

polyethylene, he flow is measured by melt index. The higher the melt index, the better

the flow. Most rotomolding resins have melt indices ranging from 2g/10 minutes to

10g/10 minutes. The term “g/10 minutes” refers to the weight of molten resin moving

through an orifice of a predetermined size in 10 minutes. The melt index is also a

rough measure of the molecular weight or the chain length of a resin. A resin

With a high melt index has shorter chains and a lower molecular weight or

smaller molecules. A resin with a low melt index has longer chains and a higher

molecular weight or larger molecules. Molecular weight distribution is also important

in a rotomolding resin. A narrow distribution is more advantageous, since the

narrower the distribution, the more uniform the melt properties. Density is a measure

of the specific gravity of a resin. The density of polyethylene is classified by types

according to the American Society of Testing and Materials (ASTM):

AN INCREASE IN MELT INDEX and DENSITY AFFECTS THESE PROPERTIES

LDPE HDPE

Melting Point decreases Increases

Flow Increases remains the same

Impact Strength decreases Decreases

Stiffness remains the same increases

Vicat Softening Temp. decreases increases

Resistance to Low Temp

Brittleness

decreases decreases

Barrier Properties remain the same Increase

Table3.9: An increase in Melt Index and Density

Type I: Low Density Resins (range of 0.925 g/cm3 and below). Generally, low

density resins are preferable whenever stiffness is not essential or is undesirable, as

for many toys, and only when light loads are to be expected.

20

Type II: Medium Density Resins (range from 0.926 g/cm3 to0.940 g/cm3).

Most linear low density polyethylene resins fall within this range. Medium density

resins are useful for self- supporting items that require the higher heat-distortion

resistance or stiffness that low density resins do not provide.

Type III: High Density Resins (range from 0.941 g/cm 3 to 0.959 g/cm3).

High density resins impart the highest rigidity to the end product, which frequently

permits reduction in wall thickness.

Type IV: Very High Density Resins (0.960 g/cm3 and above.) These resins are

not currently used in rotomolding. In addition to lowering toughness and increasing

stiffness, increasing density raises the melting point, permits higher temperature limits

and improves barrier properties in the end product.

The polyethylene pellets that are normally produced in the resin

manufacturing process cannot be used for rotational molding; they must be reduced to

a much smaller particle size. This reduction is necessary to obtain good heat transfer

from the mold to the powder. The reduction also improves the flow of the particles

during melting so that oxidation does not inhibit the mold ability and development of

the physical properties of the resin. The size reduction is usually done by the resin

supplier, but can be done by the rotational molder who has grinding equipment. In

addition to mechanically ground powder, some resins are available as reactor powder

or granules. Several linear low density polyethylene’s come in powder or granular

form. Some other resins such as nylon, due to its high melt flow and small pellet size,

can be molded without grinding. Polyethylene’s have the following characteristics

that have made them the most widely used powders for rotational molding:

• They are easily ground to 35 mesh at high rates;

• They can be made thermally stable with proper stabilization additives;

• They can be molded in high-temperature, high-speed rotational molding

equipment without excessive oxidation;

• They have excellent low temperature physical properties, such as impact

strength, allowing their use in a broad temperature range;

21

• They are relatively low in cost, making them a material to consider in all cost-

effective applications;

• They are available in a wide range of densities and melt indices to fit the needs

of simple, no stressed items as well as extremely large, highly stressed

applications;

• They can have their UV stability or outdoor life significantly improved by the

addition of pigment or UV stabilizer;

• They may meet FDA food contact requirements;

3.10 TYPES OF POLYETHYLENE

They are:

• Low Density Polyethylene (LDPE) is flexible and tough, easy to process and

has excellent chemical resistance.

• Linear Low Density Polyethylene (LLDPE) or Linear Medium Density

Polyethylene (LMDPE) has better mechanical properties than LDPE as well as

higher stiffness, excellent low temperature impact strength and excellent

environmental stress crack resistance.

• High Density Polyethylene (HDPE) is the stiffest resin of the polyethylene

family. HDPE has excellent chemical resistance and good process ability.

3.11 Molds for Rotational Molding (Inexpensive and Lightweight)

Since very little pressure is exerted in the rotomolding process and no coring

for cooling is necessary, rotational molds can be relatively simple. Because of this

simplicity, the cost of a rotational mold is a fraction of that for a comparable injection

or blow mold. Two-piece molds are the industry standard, but three piece molds are

sometimes required to facilitate proper removal of the finished parts. Molds can be as

simple as a round object or complex with undercuts, ribs and tapers. Selection of

rotational molds depends on the size, shape and surface finish of the piece to be

molded, as well as the number of molds made for a particular piece. Molds should be

as thin-walled and lightweight as possible.

22

3.12 TYPES OF MOULDS

The most important property of a rotational mold is that its interior surface has

to be completely non-porous. Cast aluminum molds are by far the most frequently

used molds in the rotomolding industry. Most parts that are small- to medium sized

are molded with a cast aluminum mold. Cast aluminum has good heat-transfer

characteristics and is cost effective when several molds of the same shape are

required. The only drawbacks to cast aluminum are it can be porous and easily

damaged. Sheet metal molds are normally used for larger parts. They are easy to

fabricate and, in many cases, the sections of the mold need only be welded together.

Sheet metal molds are cost effective when larger single-mold parts are required. Other

molds, such as electro-formed nickel molds, yield an end product with very fine

detail. Vapor-formed nickel molds, like electro-formed molds, also yield very good

detail but are more costly. CNC-machined molds and composite molds with jacketed

heating elements are also used.

3.12.1 FLANGE-MATING, SURFACES AND HINGES

Each mold must be in two or more sections requiring good parting lines to

have proper fit of the mold sections. Proper fit of the parting lines also yields little or

no flash of the resin being used and provides correct formation of the finished part.

The mating surfaces should be machined smooth for a good fit and the molds should

be stress-relieved before the parting lines are matched. The best parting line cannot

function properly without a good clamping system. The most common clamping

system for small-to-medium parts is the “C” vise clamp. Spring-loaded clamps,

welded onto the sections of the mold, are another popular option. As the molds get

larger, nuts and threaded bolts are normally used. The threaded bolts are usually

removed and installed with an air gun.

23

3.12.2 MOULD MOUNTING

Molds must be mounted on the spindle or arm of the rotational molding

machine. Large sheet metal molds are easily mounted by bolts or simple clamping

systems. With cast aluminum molds, a structure commonly known as a spider can be

used to mount several small-to medium-sized molds on the same spindle or arm. The

spider consists of several arms or mounting legs to which each mold is attached,

usually by bolts. In turn, the spider has one, central, mounting location that attaches to

the machine spindle. This design allows two- or three-dozen cast molds to be mounted

on one central structure. The spider or a single large sheet metal mold may be

removed easily with a forklift or crane. This is important because the rotomolding

process typically is used for short production runs of a variety of parts.

3.12.3 INSULATION LIDS AND COVERINGS

When openings are desired in rotationally molded pieces, insulating lids or

inserts can be used. An insulating material is applied to an area of the mold to keep

the powder from fusing at that point. Teflon and silicon foams, among other materials,

are commonly used. If thin-walled sections are desired in a molded piece, they can

also be obtained by covering a section of the mold with an insulting material that

results in a small amount of powder sticking to the mold. The wall thickness can be

controlled to a degree by changing the type or thickness of the insulating material.

3.12.4 VENTING

Because of the inherent build-up of gas in the heating cycle of the rotational

molding process, most rotational molds require a venting system. A vent reduces flash

and piece or mold distortion. It also prevents blowouts caused by pressure and permits

the use of thinner-walled molds. Depending on the size of the mold, vents can range

from 1/8" to 2" inside diameter (I.D.). An industry rule of thumb is to use 1/2" I.D.

tube for each cubic yard of part volume. Since vents leave holes in the molded parts,

correct placement is essential. The vents should be located in an area that may be cut

out of the finished part or in an area where a patch does not reduce the aesthetic value

of the end product. Improper venting can cause many molding problems, such as

water tracking on the inside of the end product.

24

3.12.5 MOULD RELEASE

Since most rotational molds are designed with little or no draft angle, it is

important to condition the molds with a release agent. Normally, molds are cleaned

with a solvent and a lightly abrasive cloth to remove all foreign particles left on the

surface during fabrication of the mold. After the mold is cleaned, a light coating of

release agent is applied and baked-on to insure a good coating. With moderate use, the

release agent does not adversely affect paint adhesion after flame treatment.

Environmental concerns have led to the development of water-based mold releases

which are taking the place of solvent-based releases. Many molders are eliminating

mold releases altogether by having molds coated with a fluoropolymer.

3.13 ROTOMOULDING EUIPMENT

The equipment used in rotational molding is relatively simple but has many

variations. The most common type of rotomolding machine is a multiple-spindle or

carousel machine. Carousel machines are usually wheel-shaped. The spindles, each

carrying a group of molds or a single large mold, are mounted on a central hub and

driven by variable motor drives. Most carousels have the freedom to rotate in a

complete circle. The carousel consists of a heating station or oven and a cooling

station. In many cases, the carousel also is equipped with an enclosed chamber and a

loading and unloading station. The shuttle-type machine. A frame for holding one

mold is mounted on a movable bed. Incorporated in the bed are the drive motors for

urning the mold biaxially. The bed is on a track that allows the mold and the bed to

move into and out of the oven. After the heating cycle is complete, the mold is moved

into a non-enclosed cooling station. A duplicate bed with a mold is then sent into the

oven from the opposite end. The clamshell utilizes an enclosed oven that also serves

as the cooling station. This machine uses only one arm and the heating,cooling and

loading/unloading stations are all in the same location.

3.13.1 Heating Stations

Most rotomolding ovens are fired by natural gas, using blowers to distribute

heat throughout the chamber. Some ovens have the capability to be heated by oil or

propane gas, but natural gas is the preferred method. Normal oven temperatures are

25

400° to 850°F (270° to 454°C). Ovens must be well insulated to minimize heat loss.

Hot-air convection is the most commonly used heat source, although hot-liquid

conduction and infrared radiation are also used.

3.13.2Mold Cooling Stations

The cooling station may use a system to provide forced air for initial cooling

and a water system to provide the necessary cooling of the molds and parts. Normally,

a spray mist is used for even cooling. In many cases, however, only air-cooling is

used. During the cooling process, the mold should be rotated. The cooling station may

or may not be enclosed.

3.13.3 Instrumentation

Several advancements in instrumentation include computer simulation

programs and data monitoring systems that help the rotational molder develop

optimum cycle times and improve their molding efficiency.

3.13.4 Finishing Rotationally Molded Pieces

Pigment loadings in polyethylene powders for rotomolding should be kept to a

minimum because high levels may cause reductions in the tensile, yield and impact

strengths of the end product. Any appropriate flame or electronic pre-treatment

method can be used to promote ink and paint adhesion in printing and painting. Other

than the desired end-product decoration, rotational molding requires practically no

post-treatment. If there is flash along the mold parting line, it must be removed,

although the creation of flash in rotational molding is usually negligible. The addition

of color to rotationally molded pieces is easily accomplished. The rotational molder

may dry blend a color pigment into the natural powder. In this process proper

dispersion is essential (one-quarter of one percent should be the maximum level

used). Another way to add color in the rotomolding process is by using a resin with

compounded-in color. New developments in color technology allow parts to change

color when under temperature. Granite and sandstone colors are also available.

Graphics can be molded-in or applied as a post-molding step. Multi-axis routers allow

for precision trimming of parts.

26

Figure 3 : Finished Product

Figure 4 : Lid

3.14 Testing Process of the Product

27

The finished Paani genie product was tested out, to check if it met with the

minimum design specifications and requirements, for the project to be successful.

The test’s performed are:

•Visual appearance - The visual appearance of objects is given by the way in

which they reflect and transmit light. The color of objects is determined by the

parts of the spectrum of (incident white) light that are reflected or transmitted

without being absorbed. Additional appearance attributes are based on the

directional distribution of reflected (BRDF) or transmitted light (BTDF)

described by attributes like glossy, shiny versus dull, matte, clear, turbid, distinct

•Capacity – The capacity of object is given by the way as how much volume of

liquid the object can contain within. This gives the total value of the internal

space provided.

•Overall height – This test will provide us with the total height of the whole

object. The vertical length, if it’s up to specified designed requirements.

•Overall diameter – This test will provide us with the total diameter of the whole

roller. This has to meet the product design requirement for the roller to have a

certain carrying volume capacity.

•Internal diameter of the manhole – This test will provide us with the results of

the internal diameter of the opening of the paani genie.

•Material identification - testing is the analysis of materials to determine the

chemical composition of a metal or alloy at particular (usually multiple) steps of

alloy manufacturing or in-process alloy installation. Knowing the exact

composition and grade of an alloy enables suppliers, plant workers, and other

responsible parties in the chain of custody of components to match alloy

specifications that are chosen for their specific properties such as heat resistance,

corrosion resistance, durability, etc. Having the right alloy in the right place is

essential in places like petroleum refineries and chemical plants, because the right

alloy with the right properties is often all that stands between a safe, efficient

operation and lost time and revenue.

•Density – this will measure the mass of the atoms or molecules that makes up

the material and the volume or amount of space the material takes up. If the

molecules or atoms are “packed” in more closely, it will be denser.

28

•Melt flow index - is a measure of the ease of flow of the melt of a thermoplastic

polymer. It is defined as the mass of polymer, in grams, flowing in ten minutes

through a capillary of a specific diameter and length by a pressure applied via

prescribed alternative gravimetric weights for alternative prescribed temperatures.

Polymer processors usually correlate the value of MFI with the polymer grade

that they have to choose for different processes, and most often this value is not

accompanied by the units, because it is taken for granted to be g/10min.

Similarly, the test load conditions of MFI measurement is normally expressed in

kilograms rather than any other units.

•Wall thickness - Wall thickness measurement is the most often applied

ultrasonic testing technique. Precision wall thickness measurement is mainly used

for the quality control of individual and serial parts. It may either be carried out

manually or by means of ultrasonic systems integrated into the production

process. Suitable side conditions allow for wall thickness measurement with a

tolerance of ± 0,01 mm. This method is more often used for the detection of

erosion and corrosion damages than for precision wall thickness measurement. In

comparison with the mechanical measuring the ultrasonic wall thickness

measurement is of advantage because it may be carried out even if only one side

of the part to be tested is accessible for the NDT-technician. Thus for instance the

wall thickness of tubes in operation may be determined by ultrasound without any

problems. Layer thickness testing may be considered to be a special case of wall

thickness measurement. However, for this purpose are not only applied ultrasonic

but also electric-magnetic procedures.

•Resistance to deformation - Deformation testing evaluates the effect that load

has on the shape of a sample. It is the measurement of a sample material to

withstand a permanent deformation and/or the ability of the sample to return to its

original shape after deforming. Deformation is measured as the percent change in

height of a sample, under a specified load, for a specified period of time. A spring

test is a type of deformation test where a spring is compressed to an L1 and L2

height and the load measurement is taken at each point and compared to a

specified load.

•Resistance to Impact - is an ASTM standard method of determining the impact

resistance of materials. An arm held at a specific height (constant potential

29

energy) is released. The arm hits the sample.The specimen either breaks or the

weight rests on the specimen. From the energy absorbed by the sample, its impact

energy is determined. A notched sample is generally used to determine impact

energy and notch sensitivity.

•Tensile strength - is a fundamental materials science test in which a sample is

subjected to a controlled tension until failure. The results from the test are

commonly used to select a material for an application, for quality control, and to

predict how a material will react under other types of forces. Properties that are

directly measured via a tensile test are ultimate tensile strength, maximum

elongation and reduction in area. From these measurements the following

properties can also be determined: Young's modulus, Poisson's ratio, yield

strength, and strain-hardening characteristics. Uniaxial tensile testing is the most

commonly used for obtaining the mechanical characteristics of isotropic

materials. For anisotropic materials, such as composite materials and textiles,

biaxial tensile testing is required

•Flexural Modulus - also known as modulus of rupture, bend strength, or fracture

strength, is a material property, defined as the stress in a material just before it

yields in a flexure test. The transverse bending test is most frequently employed,

in which a specimen having either a circular or rectangular cross-section is bent

until fracture or yielding using a three point flexural test technique. The flexural

strength represents the highest stress experienced within the material at its

moment of rupture.

The following tests were carried out at CIPET or Central Institute of Plastics Engi-

neering and Technology is an autonomous institute under the department of chemicals

and petrochemicals, Ministry of Chemicals and Fertilizers, Government of India.

30

S.No Property Standard Units Results obtained

1Visual appearance

Both internal and external surfaces are smooth, clean and free from other defects2 Capacity litre 903 Overall height kg 8,84 Overall diameter mm 465,185 Internal diameter of the manhole mm 134,466 Material identification HDPE7 Density ASTM D792 g/cc 0,928 Melt flow index ASTM D1238g/10min 5,349 Wall thickness  mm 8,457

10 Resistance to deformation % 0,1211 Resistance to Impact No crack No Puncture12 Tensile strength Mpa 19,313 Flexural Modulus MPa 845,714 Overall Migration IS9845

at 70 deg Ca) distilled water mg/dm 2̂ 2,86b)Ageous Solution mg/dm 2̂ 3,46

Table 3.10 Test Results from CIPET

31

CHAPTER 4

4.1 CONCLUSION

The innovative design allows water to be placed inside the “wheel” rather than

carried above the wheel. The 90kg (200 pound) weight of water is borne on the

ground resulting in an effective weight of just 10kg (22 pounds) on level ground.

Children and the elderly can easily manage a full roller over most types of terrain. Ex-

tensive field tests over many years and various awards have proven the effectiveness

of the Paani Genie. Approximately five times the normal amount of water can now be

collected in less time with far less effort.

The drum is manufactured from UV stabilized Polyethylene and has been de-

signed to withstand typical rural conditions such as uneven footpaths, rocks and even

broken bottles. The large opening (135 mm / 5.3 inch diameter) allows for easy filling

and cleaning of the interior. The sealed lid ensures hygienic storage of water and the

steel handle provides firm control over difficult terrain while pushing or pulling the

roller.

4.2 Future Enhancement

The project initially requires the input of donor funds in order to operate, as

the high cost of the Paani Genie places it out of the price range of the families who

need it most. The tremendous emotional appeal of the Hippo roller lends itself to se-

curing donor funding. Another major source of funding is the appeal for marketing

spin-offs from the CSI (corporate social investment) budgets which helps to encour-

age corporate involvement. We also partner with other NGO’s that have their own in-

frastructure and source of donor funding. We have also contracted a local company

that sells corporate gifts to corporate businesses. Their clients were asking for social

responsibility gifts and the project was a perfect fit. Current distribution levels are

around 1,500 rollers annually and we expect this to ramp up dramatically this year.

More students are welcome to join our cause, and to give them a platform to serve the

public. This platform enables students from our college to venture forward and inno-

vate new ideas to increase basic life in rural and needy India.

32

5. APPENDICES

Article for the newspaper; The Hindu:

“When a Genie comes to rescue…”

Many may have seen people in the villages and in the outskirts of the city, carry-

ing pots or huge containers of water on their heads or hips. Have we ever given a

thought of how difficult it is carry it to and fro? Here is where ‘Moving Forward’

comes to play.

Moving Forward is a non-profit organisation which aims at generating solutions

to tackle perennial problems of the underprivileged in India. Created by like-

minded college-goers, this organization has started their first project called the

‘Paani genie.’ This is inspired by the Hippo Water Roller which is a South

African project that was started in the 1990s.

The Paani genie is a 90-litre cylindrical water roller. It has two holes in the hori-

zontal side onto which a rod is attached. It allows the user to pull or push the

roller at an angle of 180 degrees. So, it could reduce 6 trips of carrying 15 litre

water pots to one!

Figure 3: Paani GenieAfter an immense survey, Moving Forward had selected Vinayanganallur as their

pilot village. Situated at a place which is two and a half hours from Chennai, this

village has 205 homes and survives on agriculture.

33

Moving Forward has been successful in this village and has used crowd funding

to do this project. “This project has been successful in the first village. Now we

are planning to spread this project to other villages as well,” says Maanasa Mad-

hukrishna, who heads Moving Forward.

6. REFERENCES

1. Social Impact of the Hippo Water Roller, retrieved 02 November 2015

2. MediaClubSouthAfrica: Tapping into Ingenuity, retrieved 27 September 2008.

3. Ward, Noel M. (Winter 1997). "A History of Rotational Moulding". Platiquarian

Reprints. Archived from the original on 2009-12-03. Retrieved 2009-12-03.Beall,

Glenn (1998). Rotational Molding. Hanser Gardner Publications. p. 152.

ISBN 978-1-56990-260-8.

4. Beall, Glenn (1998), Rotational Molding, Hanser Gardner Publications,

ISBN 978-1-56990-260-8.

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