Chapter 3

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CHAPTER 3: DESIGN

3 Design

In designing and fabricating this tin can crusher, a flow of methods had to be used the

design and crusher the tin. First of all, a process planning had to be charted out. This acts as a

guideline to be followed so that, the final model meets the requirement and time could be

managed. This would determine the efficiency of the project to be done. Regulating and

analyzing these steps are very important as each of it has its own criteria to be followed.

3.1 Viability of the Project Design

As discussed above this project has a lot of relevance with one of the burning issues that

is capturing the world at the moment, i.e. Waste Management.

Pollutants of all kinds are visible at every establishment of human kind. Waste has been although

treated by certain techniques, yet the storage of waste before it is treated / recycled is a topic of

vital importance and research.

Fig. 3.1 – Dimensions of Can

Focusing on the storage of the used tin / aluminum cans, the volume of a can can be calculated as

follows:

Size of a can:

Diameter (d) = 50mm

Length (L) = 150mm

Volume of a can (V) = π/4 x d2 x L

= 22/7 x 0.25 x 50 x 50 x 150

Φ 50mm

L = 150mm

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= 294642.86 mm3

= 294.64286 cm3

Weight of an empty can (w) = 15gms

Thus it’s clear that nearly 300 sq. cm of space is occupied by an empty can. Although it is not

too much, nor is the weight of a single can of much bother, the scenario gets out of control when

a large quantum of over a thousand can is considered.

Volume of 1000 cans = V x 1000

= 294642.86cm3

Weight of 1000 cans = w x 1000

= 15000gms

= 15kgs

During the trial stages of the project, it was found that a can when crushed reduces to roughly

1/7th of its initial volume. Taking this rough value, the net volume of the 1000 crushed cans can

be calculated as follows:

Volume of crushed can (Vc) = V x 1000 / 7

= 49107.143cm3

This volume is roughly equivalent to that occupied by two large domestic buckets.

Thus the viability of crushing the cans for the purpose of aiding their storage is justified.

Now focusing on the transportation aspect of the cans from the storage region to the recycling

unit:

Dimensions of a pickup truck to transport the cans to the recycling unit

= 5’ x 4’ x 2’

Volume of Truck (Vt) = 1500 x 1200 x 600

= 1.08 x 109 mm

3

= 1080000cm3

No. of uncrushed cans that can be stacked in the truck = Vt / V

(N) = 1080000 / 294.64286

= 3665.45

= 3666

Net weight of uncrushed cans fitted in the truck = N x w

= 3666 x 15

= 54990gms

= 54.9kgs

Capacity of the truck = 1 Ton

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Net usage of the truck’s capacity = 54.9 / 1000 x 100

= 5.49%

It is thus concluded that if the cans are not crushed before stacking them off for transportation,

they would use only about 5.5% of the available capacity of the truck to carry them. This in turn

leads to less profit available to the firm running the service as more rounds and time would be

needed to take the large quantum of cans for recycling.

If a contraption was to be designed such that the volume of the cans is significantly reduced, so

that in a fixed space more number of net cans can be stacked in, this could be applied to ensure

more cans are transported to the recycling unit per visit of the truck. This contraption is made

using the Can Crusher. Its viability is explained as follows:

Volume of crushed can (Vc) = 42.091837cm3

No. of crushed cans that can fit into the truck = Vt / Vc

(Nc) = 1080000 / 42.091837

= 25658.182

= 25659

Weight of the cans carried in a single lot in the truck = Nc x 15

= 384885gms

= 384.885kgs

Net usage of the trucks’ capacity = 384.885 / 1000 x 100

= 38.48%

Thus it can be seen that crushing the can to 1/7th of its original size enables the working capacity

of the truck to increase to almost 40%, thus causing more efficient working conditions of the

company operating the service.

Hence the viability of the Project of the Design and Fabrication of a Pneumatic Can Crusher is

justified.

3.2 Flow Chart

The flow chart starts with the introduction. Here, the introduction is first plan to start the

project. The supervisor requested for understanding of the project and to do some research about

the project title. Student makes project synopsis, objective, and scope of work, problem

statement and planning.

Once the introduction is done, the supervisor requested for the understanding of the

project. Thus, literature review on the title is done thoroughly covering all the aspect of the

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project. The medium for this research are via internet and books. Essential information related to

the project is gathered for referencing.

In conceptualization, few designs are done using the sketching which is then saved to be

reviewed. Sketch four concepts suitable for the project with a 3-dimensional and understanding.

The sketching is first step for designer used of the time.

The designs and concepts are than reviewed and recalculated to fit the best dimensions

and performance of recycle bin tin can crusher. After four design sketched, design consideration

have been made and one design have been chosen.

The selected design sketched is then transfer to solid modeling and drawing using solid

work application. Software is used because it gives a better dimension of recycle bin tin can

crusher compared to manual draw and is much easier to use.

However, the drawing using software is just a guideline to be followed to improve the

recycle bin tin can crusher. After drawing is done, the project proceeds to next step that is

fabrication process. The finished drawing and sketching is used as a reference by following the

measurement and the type of material needed. The fabrication process that involved is cutting,

welding, drilling, bending and other. After every process was finish, the parts are check to make

sure that the output of the process obeys the product requirement.

If all the parts had been processed, the parts are joined together to produce full scale

recycle bin tin can crusher. Here come the analysis processes. The recycle bin tin can crusher

will be test to see if it fulfills the requirement such as easy to crusher the tin, easy to bring

anywhere, strength and recycling. During the testing, if problem occur such as cant crusher the

tin, the recycle bin tin can crusher will step back to previous process to fix back the problem. The

recycle bin tin can crusher is expected to have an error that may cause the part to be redesigned

again. The recycle tin can crusher is finished by doing some finishing process such as grinding

and spraying.

After all parts had been joined together and analysis, the last phase of process that is

result and discussion. In result and discussion, the draft report and the entire related article are

gathered and hand over to the supervisor for error checking.

For the conclusion, the finish product will be compare with the report to make sure that

there is no mistake on both project and report.

After the product and report had been approve by the supervisor, the report is rearrange and print

out to submit at supervisor, the project coordinator and faculty of Mechanical Engineering. In

this stage, the final presentation was also being prepared and waited to be present.

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Fig 3.2 – Flow Chart Diagram of Design and Fabrication of Project

INTRODUCTION

LITERATURE REVIEW

YES

YES

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3.3 Drawing

The drawings are diving into two categories, which are:

1. Sketching: All the ideals for tin can crusher fabrication are sketched on the paper to

ensure that ideas selection can be made after the selected design choose.

2. AutoCAD Sketching: The design or concept sketched is transfer to solid modeling and

drawing using AutoCAD Application.

3.4 Sketching and Drawing Sections

Out of all the designs that the authors had studied the following four were analyzed with detail

and their analysis is as follows:

3.4.1 Concept 1 – Slider Crank Mechanism

The Slider Crank Mechanism is a modification of the basic four bar chain. It consists of

one sliding pair and three turning pairs. It is usually found in the reciprocating steam engine

mechanism. This type of mechanism converts rotary motion into reciprocating motion and visa -

versa. In the case that is required for the can crushing mechanism it is required to use the rotary

motion to reciprocating. The rotary motion would be provided by a motor attached to the

mechanism and the reciprocating would cause the actual can crushing.

This concept was rejected due to its simplicity and non usage for large scale purposes.

Fig. 3.3 – Slider Crank Mechanism

3.4.2 Concept 2 – Hydraulic Press Mechanism with Direct Feeding

The Hydraulic Press Mechanism is a concept that involves the crushing and the compacting of

many cans at a single go. This mechanism would involve the feeding of many cans into a mouth

sort of contraption. With a large hydraulic press mechanism the cans were to be compacted in the

shape of a cube. This made the compacting and stacking of many cans in a very elegant manner.

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The major drawback of this concept was the very high cost, the hydraulic oils used in it and the

large feed of cans required to show its practical viability. Thus this concept was not accepted.

3.3.3 Concept 3 – Automatic Feeding on Pneumatic Press with Conveyor Mechanism

Fig 3.4 – Automatic Feeding Mechanism with Conveyor

A very basic and widely appreciated concept was the one that involved the feeding of the

cans through a hopper onto a moving conveyor. The conveyor would be fitted with certain

orienting contraptions that ensure the cans enter a magazine in the orientation it is required to be

crushed in. the magazine of the cans was a large casing that would have 3-4 cans fitting into

them. The cans would fall into the plate where the pneumatic operated ram is to crush it.

The concept had to be rejected due to the exceeding budget and the excessive time that

seemed to be invested in the same.

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Fig. 3.5 – Orienting Mechanism in Automatic Feeding Mechanism

Concept 4 – Direct Feeding in Pneumatic Ram Mechanism

Fig. 3.6 – Direct Feeding Mechanism

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The finally accepted concept turned out to be a rather simple contraption than what was

otherwise selected. A hopper placed directly on top of the crushing mechanism feeds 4-5 cans in

to the crushing chamber. Motor drives a rotating curved plate that feeds the cans one by one in

line with the crushing axis.

The further parts and the entire project are detailed in subsequent parts of the report.

3.5 Concept Generation and Evaluation

Table 3.1 – Matrix Comparison Chart of various Project Concepts

Criteria Concept 1 Concept 2 Concept 3 Concept 4 Best Concept

Portability ***** * *** **** 1

Acceptance by Supervisor * ** **** ***** 4

Light Weight **** * ** ***** 4

Cost Economics **** * ** **** 1 & 4

Ease in Operation ***** **** ** **** 1

Safety Measures *** * *** **** 4

Ease in Manufacturing ***** * ** *** 1

Standard Availability *** ** *** **** 4

Key

From the details of the Chart Depicted above, the clear

advantage of adopting the design in the Concept 4 can be

analyzed.

This justifies the authors adopting this concept for the Project.

* Very Bad

** Bad

*** Average

**** Good

***** Very Good

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3.6 Design and Specifications

3.6.1 Double acting Pneumatic Cylinder

Outer Diameter (D1) = 63mm

Diameter of Piston Rod (D2) = 10 mm

Stroke length (L) = 200 mm

3.6.2 Two –Stage Single Cylinder Reciprocation Air Compressor

Model = ELGI, Chennai – TS03HN

Piston Displacement = 311 Lpm

Free Air Delivery = 250 Lpm

Motor Power = 2 HP

Motor RPM = 420

Compressor RPM = 925

Tank Capacity = 220 Liters

Net Weight = 200 kgs

Fig. 3.7 – Two Stage Single Cylinder Reciprocating Air Compressor, ELGI make

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3.7 Calculations

To calculate the force required to crush a can the formula to be applied is Euler’s

Crushing Formula. When a cylinder is subjected to a sudden compressive load (impact load) or a

gradually increasing load a stage will reach when the cylinder will be subjected to ultimate load.

Beyond this the cylinder will fail by crushing and the load will be known as crushing load.

According to Euler’s Formula

Crushing Load (W) = (Cπ2EI) / L

2

Modulus of elasticity of Aluminum (E) = 69GPa

= 69x10^9N/m2

= 69

= 69 x 103 N/mm

2

Length of uncrushed can (l) = 130mm

Equivalent Length of can (L) = 2 x l

= 260mm

Moment of Inertia of hollow cylinder (I) = π (do4 – di

4) / 64

do = outer diameter of the can = 51mm

di = inner diameter of the can = 50mm

Constant, representing the end conditions of the column (C)

This is the case of one end fixed and other end free.

Thus the value of C = 0.25

Inserting above values in the Euler’s Formula

W = [0.25 x π2 x 69x10

3 x {π/64 (51

4 – 50

4)}] / (260

2) N

= 6269.253 N

Consider Safety Factor (FoS) = 10

Safe Load for Crushing (Ws) = 626.9 N

Now that the load required to crush the can is obtained, the pressure at which the

pneumatic ram is to be subjected to get the corresponding crushing load is evaluated as follows.

Diameter of pneumatic ran piston (dr) = 65mm

Cross Section Area of Ram (Ar) = π/4 x 652

= 3318.307

Working Pressure of Ram (P) = Ws / Ar

= 0.1928 N/mm2

= 1.9 kg/cm2

= 2.0 bar

From the above discussion it is concluded that the pressure supplied to the pneumatic ram should

be about 2.2 bars to get the crushing effect on the cans.

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3.8 Calculations of Energy Efficiency of Pneumatic Can Crusher

3.8.1 Observations Regarding the Energy Efficiency

1. For proper crushing of can, it has been found experimentally that there is a need to raise

the pressure of two stage Reciprocating Air Compressor up to 5 bars

2. It was observed that 1600 blinks of LED on Multistage Reciprocating Compressor Test

Rig gives reading of 1Kwh

3. It has been found that total number of blinks to reach pressure from 0 to 5 bars (kgf/cm2)

is 178

4. No’s of can crushed at different pressure level

a. When pressure dropped from 5 to 4 Bars in compressor;

No’s of can crushed = 10

b. When pressure dropped from 4 to 3 Bars in compressor;

No’s of can crushed = 16

c. Below 3 Bars pressure;

No’s of can crushed = 5

Fig. 3.8 – Two Stage Reciprocating Air Compressor Test Rig

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3.8.2 Calculations of Energy Efficiency

3.8.2.1 Input Energy

Energy supplied to raise the pressure up to 5 bar = E

1600 LED blinks on Test Rig = 1kwh

= 103×3600 J

Thus, 178 LED blinks on Test Rig = 103×3600 ×178/1600 J

= 400500 J

Consider the efficiency of Air Compressor = 0.33

So Net Energy Supplied (E) = 0.33 × 400500 J

= 132165 J

3.8.2.2 Work Done by Pneumatic Can Crusher

Force exerted by double acting cylinder on output stroke

(FO) = PπD12 /4

So force exerted at 5 Bar (FO5) = 1559 N

So force exerted at 4 Bar (FO4) = 1247 N

So force exerted at 3 Bar (FO3) = 935 N

Force exerted by double acting cylinder on input stroke can be expressed as

(FI) = Pπ(D12-D2

2)/4

So force exerted at 5 Bar (FI5) = 1519 N

So force exerted at 4 Bar (FO4) = 1215 N

So force exerted at 3 Bar (FO3) = 700 N

Stroke Length of Ram (L) = 200mm

No’s of can crushed between 5-4 bar = 10

So work done (W5-4) = 10 × 0.2 × (1559 + 1519)

= 6159 J

No’s of can crushed between 4-3 bar = 16

So work done (W4-3) = 16 × 0.2 × (1247 + 1215)

= 7878 J

No’s of can crushed between 4-3 bar = 5

So work done (W3) = 5 × 0.2 × (700 + 935)

= 1635 J

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Total Work Done by crusher = W5-4 + W4-3 + W3)

=15672 J

Mechanical Efficiency of crusher = Total Work Done / Input Energy x 100

= (15672/132165) × 100

= 12 % *

* the valve of the working efficiency of the pneumatic can crusher is taking into consideration

of the work done by the compressor in achieving the minimum if 3 Bar pressure to begin the

crushing process. This energy spent gives no useful output but is still necessary to get to 5

Bar working pressure where the crushing takes place.

Fig. 3.9 – Apparatus of Air Compressor and Test Rig

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3.9 Computer Aided Design Drawing

After a design has been selected, the next step in designing process is dimensioning. The

design is separated into part by part and the dimensioning process is firstly sketched on the

paper. The dimensioning is base on relevant dimensions and also referring the existence cycle tin

can crusher so that the design is fit into other part. After dimensioning, the drawing of the design

is drawn using AutoCAD application; at this stage solid modeling method is used.

Part by part solid modeling create according to the dimension done before, after all part

create, the 3D model is assemble with each other base on the design.

Fig. 3.10 – Overall Views of the Design

HOPPER – CAN FEEDING MAGAZINE – CAN

ALLIGNMENT FRAME

PNEUMATIC RAM

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3.8 Design Specification of the Project – Equipment Wise

The Magazine

Material – MS Sheet Metal 16 gauge

70mm thick, 170mm wide and 350mm long

Two layers of magazine to accommodate the

rotating of the cans

Covered with acrylic plates to safeguard the cans

and the operator and provide visibility

All welding done by SMAW process

Fig. 3.11 – The Magazine

The Frame

Material – MS Sheet Metal 16 gauge

300mm tall frame

900 x 350 mm size of plate

L – clamps for fitting pneumatic press welded on

the base

Fittings for 5/2 pneumatic solenoid valve

All welding done be SMAW process

Fig. 3.12 – The Frame

The Hopper

Material - MS Sheet Metal 16 gauge

Square Frustum shape

Top open size – 300 x 150mm

Bottom open size – 70 x 170mm

Tack Welding of all joints done by SMAW

welding

Fig. 3.13 – The Hopper

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The Rotating Mechanism

Motor – MarutiTM

Windscreen Viper, high

torque low speed, 12v output

Battery – 6v, 7Amp, sealed dry rechargeable

battery

Thimbles attached to make connections safe

Fig. 3.14 – The Rotating Mechanism

The Rotating Film

Material – MS Sheet Metal 16 gauge

Un-bended size – 20 x 60mm

Curved using simple light presses

Attached to the motor and frame with bolt

L – clamp welded using SMAW process

Fig. 3.15 – The Rotating Film

The Pneumatic Ram

200mm stroke length

63mm diameter

Double acting pneumatic piston

Heavy Duty Operation

Fig. 3.16 – The Pneumatic Ram

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The 5/2 Pneumatic Solenoid Valve

As studied in Industrial Automation, the 5/2

pneumatic valve is powered by a solenoid

current.

It has 5 fitting regions and 2 positions.

Position 1 is the IN for air from the compressor

into the ram, while position 2 is the OUT for the

air to exhaust

Fig. 3.17 – The 5/2 Pneumatic Solenoid

Valve

The Timer

SelecTM

make, can adjust with accuracy in

minutes, seconds and milliseconds

Circuited to the solenoid operated pneumatic

valve to engage or disengage the pneumatic ram

Makes the entire pneumatic can crusher model

semi – automatic

Switch operated for the initial instigation of the

crushing mechanism.

Fig. 3.18 – The Timer