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History of computer mouse

Dr. Douglas Engelbart has invented the first device that came out as mouse in the year1964.During this time the only way of moving the cursor around on a computer screen was using the arrow keys on the keyboard and it was really inefficient and awkward to use. A small brick like mechanism with one button on top and two wheels on the underside was made by Douglas. The purpose of these wheels is to detect horizontal and vertical movement and on the whole the unit was little bit difficult to use. For viewing the cursor on the monitor this unit was linked to the computer by a cable so the motion signals could be electrically transmitted .As the device with its long cable tail looked like a mouse so the name "mouse" came into picture.NASA team tried different methods of moving cursors and pointing to objects on the computer screen like the devices steering wheels, knee switches, and light pens, but in tests of these devices Engel arts mouse gained popularity. Engineers thought that the mouse was perfect for drawing and drafting purposes and could develop computer aided designs at their own desks. Slowly mouse began to be called as input/output device. To make the scrolling easier the mouse began to multiply rapidly and to make the mouse cordless by using the radio frequency signals. Mouse tail is the electrical cable leading out of one end and the other end is used for connecting to the central processing unit.

Composition of the Mouse

Body of the mouse:

* The outer surface of the mouse is Hard plastic body which the user guides across a flat surface

* The tail of a mouse is an electrical cable that leads out from one end and finishes at the connection at the Central Processing Unit

* It has one to three buttons at the tail end which are external contacts to tiny electrical switches

* With a click on the button the electrical circuit is forced to close and the computer receives a command

* Below the mouse there's an plastic hatch that fits over a rubberized ball which exposes a small part of the ball

* A support wheel and two shafts hold the ball in place inside the Mouse

* Rotation of the spokes causes IR light signals from light emitting diode to flick through the spoke which are then captured by a light detector

* Phototransistors help to translate these light signals into electrical pulses which reach the integrated circuit interface in the mouse

* These pulses then confirms the IC whether the ball has followed an up down or left right movement

* The IC commands the cursor to move on the screen accordingly

* The interface IC is then ascended onto a printed circuit board

* This forms the skeleton to which each and every internal workings of the mouse are attached

* The information from the switches and signals from the phototransistors is collected by a computer chip or IC

* These are then sent to the computer by means of a data stream

The Brain of the Mouse:

* Every mouse design consists of an individual software known as driver

* These driver are external brain that enables the computer to understand the mouse signals

* The driver tells the computer how to interpret the mouse's IC data stream including speed, direction, and clicked commands

* Some mouse drivers allow the user to assign specific actions to the buttons and to adjust the mouse's resolution (the relative distances the mouse and the cursor travel).

* The Mouse which are purchased as a part of computer packages have built in drivers or is programmed initially in the computers

(Source: Fig 1 Internal circuit of the mouse

http://www.ehow.com/how-does_4574328_computer-mouse-work.html

RAW MATERIALS IN THE MOUSE

The outer shell of the mouse and the majority of its internal parts, which includes spoked wheels and shafts are usually made up of Acrylonitrile Butadiene Styrene (ABS) plastic which is usually injection moulded. The ball is basically made of metal which is rubber coated and is usually supplied by a speciality supplier

The electrical micro switches which is produced from metal and plastic are of shelf items which are supplied by subcontractors even though the designers of the mouse can specify force requirements for switches to make it easier of harder to click. The chips or IC could be standard items even though individual manufacturer might have proprietary chips which can be utilised in its complete products line. The outside source also supplies electrical cables and over moulds To suit the design of mouse the printed circuit board (PCB) over which the mechanical and electrical components are mounted are custom made Oscillators, integrated circuits, capacitors, electrical resistors and various other components are made of different types of plastic, metal and silicon

The raw materials which are used in manufacturing of a computer mouse are as follows:

Component name

Material

mouse ball

Low alloy steel

Housing

Acrylonitrile butadiene styrene (ABS)

insulation wire

Polyvinylchloride (tpPVC)

rubber material

Polyurethane (tpPUR)

USB inside part

Stainless steel

plastic part inside USB

Phenolics

USB jack(casing)

Acrylonitrile butadiene styrene (ABS)

internal wires

Copper

Mouse Design

The new mouse starts with associations with product development manager, marketing representative, designer and a consulting ergonomist. A list of human factors guidelines are formed which indicate the size range of hands, amount of work, touch sensitivity, support of hand in a neutral position, while operating the mouse the user's posture, finger extension needed to reach the buttons, use by both right and left handed individuals, no prolonged static electricity and lastly the requirements safety and comfort They alter widely depending on whether the use of mouse is in home or office computers The brief design of mouse for the proposed mouse is written to explain the purpose of the product and what it attains; an appearance is also proposed in staying along with the probable market. The design team comes back to the table along with foam models; for a single mouse design scores of various shapes are made on these models the user testing is done whereas the preliminary tests are performed by engineers or the focus may be turned onto groups as typical users or observes one to one testing with user samples.

(Source: Fig 2 Design of the mouse

http://www.computerhope.com/jargon/m/mouse.htm )

When a suitable selection is chosen, wooden models which are more refined and painted are produced from the winning design. Based on the feel, shape and looks of the model input is gathered again and the ergonomist reviews the probable designs and confirms the goal of human factors guidelines to be achieved. After an optimal design is chosen the engineering team starts designing the internal components. A three dimensional rendering is generated by the computer and the same data are used to machine cut the shape of the interiors of the exterior shell with every details. Inside the structure the mechanical and electronic engineers fit the printed circuit board and the encoder mechanism.

The phenomena of fitting the workings on to the shell is iterative, the changes are then made and then the design and fit process are repeated until the mouse achieves the design objectives and the design team is happy. The custom chips are then designed and produced on a trial basis and then tested; for the design to meet the performance objectives and provide it unique, competitive and marketable characteristics the help of custom electronics is required. The fully completed design figures are handed over to the project tooled who then starts the process of modifying machines to manufacture the mouse. To generate the injection moulding of the shell tooling diagrams are made into use.

The size, shape, volume of the cavity, the number of gates through which the plastic will be injected into the mould, and the flow of the plastic through the mold are all diagrammed and studied. After reviewing the final tooling plans the tools are cut using computer generated data. Sample plastic shells are made as try shots to find out the actual flow lines and to make sure that voids are not included. Changes are made till the process is perfect. Texture is added to the external appearance of the shell by sand blasting or by acid etching.

The Manufacturing Process:

To manufacture a computer mouse several processes are used to make different pieces of the unit. The processes that are used in manufacturing are as follows

1. First the Printed Circuit board (PCB) is prepared in the journey of manufacturing and assembling steps. This board is a flat, resin coated sheet that can be of surface-mount design or through hole design. The assembly of surface mount version is entirely done by the machine. The other electrical components are placed on to the board in prescribed pattern by a computer controlled automatic sequencer.

In the PCB assembly, the attachment wires of the electronic components are inserted in holes. Then all the components are mounted on the board, the bottom surface is passed through molten lead solder in a soldering machine. This machine removes contaminants by passing the board with flux. The board is gently heated by the machine and the components it carries by infrared heat is to lessen the possibility of thermal shock.

The solder raises each line by hair-like activity, seals the perforations and repairs the components in the correct place.

. After this process is done the PCB is cooled and is visually inspected before the mechanism is attached.

2.A separate unit is assembled for the encoder mechanism. Injection moulding process is make used to manufacture the plastic parts (computer mouse case housing) with proper specifications and the left over scrap plastic material is trimmed off. The whole unit is fastened to the PC Board using screws keeping in view after the encoder mechanism is completely assembled.

Using a set of wires ,shielding and rubber cover the mouse's tail and its electrical cable attached are manufactured. Overmolds are the additional pieces of the cable to prevent the cable from detaching from the mouse. We can make our own shapes of design for overmolds, the near mouse overmold is hooked to the housing at the opposite end of the tail, the connector is soldered to the wires and the connector overmold is pop pled into place.

2. The pieces of the outer shell are visually inspected after moulding, trimming, and surface (finish) treatment and prior to assembly. The external housing is assembled in four steps. To the bottom of the shell the completed PCB and encoder assembly are inserted. The buttons are fitted into the top part of the housing, attaching the cable and the top and bottom are screwed together using automated screwdrivers.

3. The final electronics and the achievement quality inspection are accomplished, if assembly is complete in the substantial one. Rubber or neoprene feet with the adhesive covering in front-turned at a side is added the lower surface of the mouse.

4. A programming team has been developing,testing,reproducing the mouse driver firm ware, while the the tooling designs and physical assembly are in progress. As above said "firmware" is the combination of software and hardware codes which has the unity of integrated circuit,translated mouse directional movements and micro switch signals which are understood when the mouse is attached.

By-products and waste:

Computer mice makers do not generate by-products from mouse manufacture, but most offer a range of similar devices for different applications. In order to avoid the design, tooling, assembly modification costs the new and multiple designs are in corporate when possible.

Waste is minimal. The mouse's ABS plastic skin is highly recyclable and can be ground, moulded, and reground many times. Small quantities can be recycled using metal scrap and other plastics.

ECO AUDIT TOOL

INTRODUCTION:

Eco audit tool enables the product designers to quickly evaluate the environmental impact of a product, and it helps to reduce the environmental measures. By making use of CES software, this can be achieved by focussing on two environmental stressors

* ENERGY USAGE

&

* CARBON FOOTPRINT

considering the main product life phases of a product

Overview of component lifecycle

(Source: http://www.treehugger.com/RONA-product-life-cycle-graphic.JPG )

Example output from the eco audit tool

(Source: http://www.grantadesign.com/images/selector09/EcoAuditGraph.jpg )

To minimize the environmental footprint of a product, identification of the dominant phase is very important and it enables a designer to establish which aspect of the design to target The result of the eco audit forms the objective for the product design. This objective is dependent on both the dominant phase and the product application.

Figure - Examples of design objectives associated with minimizing the environmental impact of the main life

(Source: http://www.grantadesign.com/images/audit-strategies.jpg )

Life Cycle Analysis:

The Life cycle analysis of the product life cycle is split into three main sections in the eco audit tool:

1. Material, manufacture, and end of life

2. Transport

3. Use

1. Material, manufacture, and end of life

This the first section of the product definition which allows us to enter the 'Bill of Materials'(BOM) for the product, with each line representing an individual component. There is no limit on the number of components that can be added.

Reading across the input dialog box, the entries are as follows

Quantity

This column tells us about the different number of individual components that are used in making of the product. This quantity column enables the specification of duplicate components in a hierarchal order. . The default value is one because there is no product with zero quantity.

Component name

It is the dialogue box for entering the name of each individual component of the product.

Material

The material drop-down menu displays the full Material Universe tree of the active database. Materials are selected by browsing the tree and clicking on the record for the material of our interest. Once we have done this, the eco audit tool extracts data from the material record to determine what options to display in the 'Primary process' and 'End of life' menus.

Certain products include 'components' that do not contribute to all life phases. For example, the water in a drinks bottle contributes to the transportation phase but not the material and manufacturing phases. This contribution is handled by creating a 'dummy' component with no material, or process, assigned to it.

Recycle content

We have three recycle contents which can be specified as 0%, 100%, and 'typical %'.

As the names suggest, 0% represents the use of virgin material, where all the feedstock is produced from raw materials. 100% represents the other intense, where the material is manufactured entirely from feedstock reclaimed from end of life components. Typical %, lies between these two extremes and accounts for the level of recycled material incorporated back into the supply chain as standard practice. This applies to materials, such as metals and glasses, where end of life recycling has become integrated into the supply chain. This practice leads to standard grades containing significant levels of recycled material. For example, lead alloys generally contain 50-60% recycled material.

Although many materials can be recycled, and have 'recycle fraction in current supply' values quoted in the Material universe database, they are not routinely reintroduced into the standard supply. As a result, the 'typical' recycle content option is only displayed for grades of metal and glass that are flagged as recyclable.

Primary process

The primary process dropdown menu displays the processes that are applicable to the material selected from the tree. This information, and associated data, is extracted from the material's datasheet. The available primary processes in the database are shown in the below table.

Table 1. Available primary processes (Level 1 and 2 database)

Material

Process

Metals

Casting

Forging

Metal powder forming

Vaporization

Polymers & elastomers

Polymer molding

Polymer extrusion

Technical ceramics

Ceramic powder forming

Non-technical ceramics

Assembly and construction

Glasses

Glass molding

Composites

Casting

Simple composites forming

Advanced composite forming

Natural materials

Assembly and construction

Electrical components

-

As electrical components are finished sub-assemblies, the material and process energies (and CO2) have been incorporated into one value [Embodied energy, primary production]. As a consequence, no processing options are available for these components.

Mass (kg)

Numeric field for specifying the mass of the component. This value is multiplied by the quantity (Qty) field value to determine the total mass for the component.

End of Life

This drop-down menu displays all possible end of life options for the selected material. There are seven end of life options and their applicable materials. Out of these seven, the first four are directly displayed on the datasheet depending on the type of material. The remaining life options are not specified and are added as other possible options for all materials.

The end of life option generally defaults to 'Landfill'. The main exception is for toxic materials, which default to the next viable option (usually in down cycle order').

Table : describes the possible end life options and their Summary related to the materials

End of life option

Applicable materials

Landfill

All non-toxic materials

Combust (for energy recovery)

All organic-based materials with a heat of combustion value >5 MJ/kg

Downcycle

All

Recycle

All unfilled: metals / glasses / thermoplastics /TPEs

Particulate filled thermoplastics

Particulate & whisker reinforced metals

(All ceramics / thermosets / elastomers / natural organic / natural inorganic materials and all fiber reinforced materials are marked as non-recyclable)

Re-engineer

All

Reuse

All

<blank>

All

2. Transport

Transportation phase is the second part of the product definition. This phase relates to the transport of the finished product from the source of manufacture to the customer

Each line in the table relates to one stage of the process journey. There is no limit on the number of stages that can be added. For each stage, three parameters are defined: stage name, transport efficiency (transport type), and distance.

The transport efficiency is specified through the 'transport type' dropdown menu, which lists the main methods for transporting goods.

Table : transport options and associated environmental burden

Transport energy

(MJ/tonne/km)

Carbon footprint,

source (kg/MJ)

Sea freight

0.16

0.071

River / canal freight

0.27

0.071

Rail freight

0.31

0.071

32 tonne truck

0.46

0.071

14 tonne truck

0.85

0.071

Light goods vehicle

1.4

0.071

Air freight - long haul

8.3

0.067

Air freight - short haul

15

0.067

Helicopter - Euro copter AS 350

50

0.067

To determine the environmental impact of each stage the energy usage and the carbon foot print values are combined with the product mass and distance.

i.e. Energy usage is given by

Transport Energy =Transport energy per unit mass * distance * product mass.

And carbon foot print by

Transport co2=Transport energy per unit mass*Distance*product mass*carbon foot print.

3. Use

The final stage of the product definition is the use phase.

Product life

Numeric field for specifying the product life, in years. The value for the year is considered to be default (1).

Country electricity mix

The Country electricity mix drop-down menu enables the particular mix of fossil and non-fossil fuel of the country of use to be specified. This is split into three main groups: global regions, individual countries, and fossil fuel percentage. The default option is 'World'.

Compared to the other sources, such as nuclear, hydroelectric and wind power, the environmental burden of electricity generated from fossil fuels is significantly higher. So this specification of country of use is very important phase of the eco audit tool.

This is due to the relatively low efficiency in converting fossil fuels to electricity (1MJ of electricity requires about 3MJ of fossil fuel). The impact of a country's energy mix on the energy equivalence and carbon footprint of its electricity supply is summarized in Figure3.

Figure 3. Country electricity mix: Energy equivalence & carbon footprint per MJ of electricity used

(Source: http://images.google.co.uk/imgres?imgurl=http://www.additiverich.com )

The final grouping in the 'country electricity mix' menu specifies the electricity mix based on the proportion derived from fossil fuels (0% to 100% at 5% intervals). The environmental impact of these has been calculated using the following assumptions:

a) The carbon footprint of electricity is dominated by the contribution from fossil fuels, with the proportion derived from other sources having no, or negligible, contribution.

b) And the conversion process for generating electricity from fossil fuels is taken to be 33% efficient.

In this use phase we have two modes namely static mode and mobile mode which describes the product energy usage. In static mode the available options are energy input and output which describes the conversion of one form of energy into another, power rating and usage. In the mobile mode, we have fuel and mobility type and its usage.

Modes of use

The use phase is divided into two modes of operation, static, and mobile.

Static relates to products that are (normally) stationary but require energy to function. For example: electrically powered products like electric kettles, refrigerators, and power tools.

Mobile relates to transportation systems, where mass has a large influence on energy consumption.

To define these modes of use, 'check' the 'static mode' and 'mobile mode' boxes. For products that operate in both modes, check both boxes.

Static mode:

Three parameters define the static use mode: Product efficiency, power rating, and the duty cycle.

The product efficiency is specified through the 'Energy input and output' dropdown menu. This specifies the energy conversion efficiency of the product and the environmental burden associated with its energy source . For electric products, the energy equivalence and carbon footprint values depend on the country of use

Table : Available energy conversion options and associated environmental data

Input and output type

Product efficiency

Energy equivalence,

source (MJ/MJ)

Carbon footprint,

source (kg/MJ)

Electric to thermal

1

Country specific

Country specific

Electric to mechanical (electric motors)

0.89

Country specific

Country specific

Electric to chemical (lead acid battery)

0.83

Country specific

Country specific

Electric to chemical (advanced battery)

0.89

Country specific

Country specific

Electric to em radiation (incandescent lamp)

0.17

Country specific

Country specific

Electric to em radiation (LED)

0.86

Country specific

Country specific

Fossil fuel to thermal, enclosed system

1

1

0.071

Fossil fuel to thermal, vented system

0.70

1

0.071

Fossil fuel to electric

0.35

1

0.071

Fossil fuel to mechanical, internal combustion

0.30

1

0.071

Fossil fuel to mechanical, steam turbine

0.40

1

0.071

Fossil fuel to mechanical, gas turbine

0.48

1

0.071

Light to electric (solar cell)

1*

1

0

The product power rating and duty cycle are specified by the 'Power rating' and 'Usage' inputs. These parameters are combined with the product efficiency values to determine the static mode contribution:

Static energy (J) =power rating (W)*duty cycle*(energy equivalence /production efficiency)

Static use CO2(kg) = ((power rating (W)*duty cycle)/1*10^6)) *(carbon footprint/production efficiency)

Where : Duty cycle(S)=production life (years)*days per year*(house per day*3600)

Mobile mode:

The mobile use mode is defined by three parameters: The transport type, efficiency, and the distance travelled over the product's life.

The transportation type and efficiency is specified through the 'Fuel and mobility type' drop-down menu. This determines the environmental burden associated with the transportation and fuel type . For electric transportation modes, the energy equivalence and carbon footprint values depend on the country of use.

Table 5. Available fuel and mobility types and associated environmental data

Fuel and vehicle type

Energy

(MJ/tonne.km)

Energy equivalence,

source (MJ/MJ)

Carbon footprint,

source (kg/MJ)

Diesel - ocean shipping

0.16

1

0.071

Diesel - coastal shipping

0.27

1

0.071

Diesel - rail

0.31

1

0.071

Diesel - heavy goods vehicle

0.90

1

0.071

Diesel - light goods vehicle

1.4

1

0.071

Diesel - family car

1.6

1

0.071

Electric - family car

0.17

Country specific

Country specific

Electric - rail

0.11

Country specific

Country specific

Gasoline - hybrid family car

1.1

1

0.071

Gasoline - family car

2.1

1

0.071

Gasoline - super sports and SUV

4.8

1

0.071

Kerosene - long haul aircraft

8.3

1

0.067

Kerosene - short haul aircraft

15

1

0.067

Kerosene - helicopter (Eurocopter AS 350)

50

1

0.067

LPG - family car

3.9

1

0.58

These values are combined with the product usage and distance parameters to determine the contribution of the mobile mode:

Source :( Granta Design,Cambridge,UK ,2009)

Report:

The final section in the product definition allows an image and notes to be added to the eco audit report. This is compiled by 'clicking' on the View Report button. These can be categorised into three sections:

1. Summary page - provides an overview of the eco audit, with headline values for each life phase. This enables rapid identification of the dominant life phase.

2. Detailed breakdown of energy usage (accessed via 'Energy Details...' link on summary page) - provides a component-by-component breakdown of each life phase, enabling the main contributors to the dominant phase to be identified. This page lists all data and calculation factors used by the eco audit tool.

3. Detailed breakdown of carbon footprint (accessed via 'CO2 Details...' link on summary page) - similar to above, except for carbon footprint.

The summary table quotes two totals for energy and CO2. The first value, 'Total', sums the environmental burden associated with the life of the existing product - this is similar to the approach used by life cycle assessment (LCA) techniques. The second value, 'Total (including end of life saving/burden)', includes end of life benefits that are realized in future life cycles. This value is useful for designers, looking to design for the environment, as it enables them to maximize the benefits that could be realized in future life cycles.

Source :( Granta Design,Cambridge,UK ,2009)

Product name: Computer Ball Mouse, & BOM:

Life: 4 years

COMPUTER BALL MOUSE:

Figure below shows a typical computer ball mouse. The bill of materials (BOM) of the product is listed in table. The computer mouse is manufactured in south East Asia and transported to Europe by air freight, a distance of 11,000 km then distributed by 24 tonne truck over a further 275 km. The power rating is 15 W and the mass is 68.5 gms .The computer ball mouse is a pointing device used to generate movement commands for controlling a cursor position displayed on a computer monitor or a laptop.

Step 1: Materials and manufacture: 100 units

Material:

Breakdown by component

Component

Material

Recycle content

Material Embodied Energy * (MJ/kg)

Total Mass (kg)

Energy (MJ)

%

mouse ball

Low alloy steel

Typical %

24.338

0.015

0.365

3.38

Housing

Acrylonitrile butadiene styrene (ABS)

100%

40.423

0.062

2.506

23.23

insulation wire

Polyvinylchloride (tpPVC)

100%

33.757

0.030

1.013

9.39

rubber material

Polyurethane (tpPUR)

100%

49.916

0.012

0.599

5.55

USB inside part

Stainless steel

Typical %

59.288

0.005

0.296

2.75

plasticpart inside USB

Phenolics

0% (virgin)

90.335

0.006

0.542

5.02

USB jack(casing)

Acrylonitrile butadiene styrene (ABS)

100%

40.423

0.021

0.849

7.87

internal wires

Copper

Typical %

48.115

0.096

4.619

42.81

Total

0.247

10.789

100

Mass and energy data for material phase

Component

Qty.

Part mass (kg)

Embodied Energy, primary production (MJ/kg)

Recycle fraction in current supply (%)

Embodied Energy, recycling (MJ/kg)

mouse ball

1

0.015

34.871

41.952

9.764

Housing

2

0.031

96.343

0.707

40.423

insulation wire

3

0.010

80.374

0.707

33.757

rubber material

4

0.003

118.849

0.707

49.916

USB inside part

5

0.001

81.149

37.417

22.722

plasticpart inside USB

6

0.001

90.335

0.707

0.000

USB jack(casing)

7

0.003

96.343

0.707

40.423

internal wires

8

0.012

70.937

42.895

17.734

The bar chart in the below figure shows the energy breakdown delivered by the eco audit tool. Table show the energy and co2 summary

Manufacture:

Breakdown by component

Component

Process

Processing Energy (MJ/kg)

Total Mass (kg)

Energy (MJ)

%

mouse ball

Casting

4.173

0.015

0.063

4.21

housing

Polymer molding

10.958

0.062

0.679

45.67

insulation wire

Polymer extrusion

3.575

0.030

0.107

7.21

rubber material

Polymer molding

10.129

0.012

0.122

8.17

USB inside part

Casting

4.140

0.005

0.021

1.39

plasticpart inside USB

Polymer molding

12.755

0.006

0.077

5.14

USB jack(casing)

Polymer molding

10.958

0.021

0.230

15.47

internal wires

Forging, rolling

1.975

0.096

0.190

12.74

Total

0.247

1.488

100

Step 2: Transport

For step 2 it retrieved the energy and CO2 profile of the selected transport mode from a look-up table.

Transport:

Breakdown by transport stage

Total product mass = 0.25 kg

Stage Name

Transport Type

Transport Energy (MJ/tonne.km)

Distance (km)

Energy (MJ)

%

East Europe

Rail freight

0.310

2500.000

0.191

26.00

Rotherham

14 tonne truck

0.850

126.000

0.026

3.59

Hampshire

Light goods vehicle

1.400

308.000

0.107

14.47

Birmingham

14 tonne truck

0.850

75.000

0.016

2.14

East Europe

Rail freight

0.310

2500.000

0.191

26.00

Stortford

14 tonne truck

0.850

351.000

0.074

10.01

Rothernham

14 tonne truck

0.850

126.200

0.026

3.60

Sussex

Light goods vehicle

1.400

302.000

0.104

14.19

Total

6288.200

0.736

100

Breakdown by components

Total transport distance = 6.3e+03 km

Component

Total Mass (kg)

Energy (MJ)

%

mouse ball

0.015

0.045

6.07

Housing

0.062

0.185

25.10

insulation wire

0.030

0.089

12.15

rubber material

0.012

0.036

4.86

USB inside part

0.005

0.015

2.02

plasticpart inside USB

0.006

0.018

2.43

USB jack(casing)

0.021

0.063

8.50

internal wires

0.096

0.286

38.87

Total

0.247

0.736

100

It then multiplies these by the total weight of the product and the distance travelled. If more than one Transport stage is entered; the tool sums them, storing the sum. For step 3 the tool retrieves an efficiency factor for the chosen energy conversion mode (here electric to mechanical) finding in its look-up table.

STEP 3: USE PHASE: STATIC MODE

Use:

Mode

Energy (MJ)

%

Static

0.000

Mobile

0.000

Total

0.000

100

The tool uses this and the user-entered values for power and usage to calculate the energy and CO2 profile of the use phase. For the final step 4 the tool retrieved the recycle energy and recycle fraction in current supply for each material and replaced the energy and CO2 profiles for virgin materials with values for materials made with this fraction of recycled content.

Finally it created a bar chart and summary of energy or CO2 according to user-choice and a report detailing the results of each step of the calculation. An overall reassessment of the eco impact of the computer mouse should, of course, explore ways of reducing energy and carbon in all four phases of life, seeking the most efficient methods.

Housing

Materials selected are :

1) Acrylonitrile butadiene styrene (ABS) Plastic

2) Polymethyl methacrylate (acrylic,PMMA)

3) Polystyrene (PS)

Materials used in computer mouse

Copper

Copper is used in the wiring for tail of the mouse . Copper is an excellent electrical conductor which is extremely used in wiring for power lighting ,heating and several daily purposes ,but copper are not used directly ,they are bounded with insulation wire .The metal is also used in electric and electronic compounds ,so that it can flow electricity very easily ,as it is a good conductor of electricity ,this is type of metal in which there are many types of contents present in the same form and in general cadmium free copper is known with the name "electrolyte copper" which is 100 pure.

Year by year the usage of copper is increasing, at present every year 15 million tonnes of copper is used .copper has several properties which are combidely remarkable .It is a good electrical and thermal conductor it is ductile and can prevent bacterial growth .recycling of copper is important as it is limited .And recycling of copper is well suited as it can be re melted without losing the properties.

Extraction of copper

In nature the metal are found in compounds which are usually combined with oxygen. The compounds are mixed up in rocks or minerals which are called as ores. A ore is a rock that has enough metal in it to make it worth extracting the metal. The main ore of copper are

* Chalcopyrite

* Bornite

* Malachite

The tree main stages of extracting copper are

* Mining

* Extraction

* Purification

Mining process: In this process the copper ore will be dug form the ground. The ore contains some mineral and lot of waste rock. For every 1000 tones 6 tonnes of copper can be extracted.

Copper electrolyte

Copper sulphate

fig explains us the electrolysis process extracting copper.

Extraction process: In this process the ore has to be changed in to metal ,this process is called reduction.

The table explains us the extraction of copper and process used.

Metal

Ore

Reactivity

Primary process

Copper

Various ore

Low

Roasting in air

Purification: In this process many metal are impure when they are extracted from there ores, impurities have to be removed copper is purified by electrolysis process as mentioned above in the figure; the copper is transformed from an impure anode to cathode of an electrolytic cell. The copper produced by this process is 99.99% pure.

Recycling of copper is very important: This process of recycling has several advantages like price, limited resources, energy efficiency, land fills costs, and the last important thing is environment.

Manufacturing process of copper used in mouse cable: There are two process used in manufacturing they are rolling and forging.

USB INSIDE PART (METAL)

1) Stainless steel

2) Medium carbon steel

3) High carbon steel

4) Low carbon steel

Stain less steel:

U.S.B port is made of stain less steel .stainless steel is defined as in ox steel which is defined as alloy steel with 11% chromium content by mass, it is stainless steel because of the content In addition to iron, carbon, and chromium, modern stainless steel may also contain other elements, such as nickel, niobium, molybdenum, and titanium. It is the addition of a minimum of 12% chromium to the steel that makes it resist rust, or stain 'less' than other types of steel. The invisible layer chrome-containing oxide named passive film can be formed by the mixture of oxygen in the atmosphere and chromium in the steel. The sizes of chromium atoms and their oxides are similar, so they pack together on the surface of the metal, forming a stable layer only a few atoms thick. If the metal is cut or scratched and the passive film is disrupted, more oxide will quickly form and recover the exposed surface, protecting it from oxidative corrosion. Iron, on the other hand, rust quickly because atomic iron is much smaller than its oxide, so the oxide forms a loose rather than tightly-packed layer and flakes away. The passive film requires oxygen to self-repair, so stainless steels have poor corrosion resistance in low-oxygen and poor circulation environments. In seawater, chlorides from the salt will attack and destroy the passive film more quickly than it can be repaired in a low oxygen environment of chromium.

Manufacturing process:

The manufacture of stain less involve several process in the first the steel is melted and then it is casted in to solid form, the heat treatment is done in then it is cleaned and the polishing of the metal is done when the desired shape is achieved.

The stages of extracting stain less steel are

* Melting and casting

* Forming

* Heat treatment

* De scaling

* Cutting

* finishing

Melting and casting: In this process the raw materials are melted together in an electric furnace. The whole process takes half days for intense heat. After the melting is done, the molten steel will be casted into different forms which include blooms (rectangular shapes), billets which are round or square in shape with 1.5 inches or 3.8 centimetres in thickness, slabs, rods, and tube rounds.

Forming: The semi finished steel goes through the forming operations with hot rolling in which heat is formed to steel and the steel is heated and passed through huge rolls .where the stain less steel is formed.

Heat treatment: Most types must go through an annealing step, before stainless steel is formed. Annealing is a heat treatment where steel is heated and cooled under controlled conditions to relieve internal stresses and soften the metal.

De scaling :De scaling is a process where Annealing is caused to build-up to form on the steel. The scale can be removed using several processes. The de scaling steps occur at different stages depending on the type of steel being worked. Bar and wire, for instance, go through further forming steps like hot rolling, forging, or extruding, after the initial hot rolling before being annealed and descaled. Sheet and strip, go through an initial annealing and descaling step after hot rolling. After cold rolling passing through rolls at a relatively low temperature, which produces a further reduction in thickness, sheet and strip are annealed and descaled again,a final cold rolling step then prepares the steel leading to final processing.

Cutting : In this process the stainless steel is done with Cutting operations which are usually necessary to obtain the desired blank shape or size to trim the part to final size. Mechanical cutting is commonly obtained to the cut in to the desired shapes

Finishing: Finishing is an important process because appearance is the important process. Certain surface finishes also make stainless steel easier to clean, which are important for sanitary applications. A smooth surface is obtained by polishing also provides better corrosion resistance. Surface finishes are the result of processes used in fabricating the various forms or are the result of further

General process used for the manufacture of stainless steel

http://www.madehow.com/images/hpm_0000_0001_0_img0192.jpg

Insulation for cables:

Materials used are:

1) Polyvinyl chloride (PVC)

2) Polyoxymethylene (POM)

3) Polyethylene Terephthalate (PET)

4) Polyetherethreketone (PEEK)

Polyvinyl chloride: copper wire is circulated by insulating wire which is made up of poly vinyl chloride It is a thermo plastic layer and also vinyl polymer constructed of repeating vinyl groups, poly vinyl is the most common produced plastic, it is noted that nearly 40 millions of tonnes is manufactured every year.

Manufacturing process:

Poly vinyl is manufactured in polymerization process. Most of the common mass is chlorine which creates a given mass of PVC; due to this it requires less polymer than any other polymer. PVC has a higher density than hydrocarbon polymers, and production of chlorine has its own energy requirements , which ends up being of little practical relevance in the production of most solid objects.The most widely used process for production is suspension polymerization. , VCM and water are added into the reactor of polymerization and initiator of polymerization, along with other chemical additives, which are added to initiate the polymerization reaction ,the reaction vessel which are contented are mixed in an order to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction comes out to be exothermic, which requires a cooling mechanism this is because it has to maintain the reactor contents at the appropriate temperature.

During the course of reaction,PVC slurry is degassed and stripped to remove excess VCM which is recycled into the next process, then passed though a centrifuge to remove most of the excess water. The slurry is then dried further in a hot air bed and the resulting powder sieved before storage or pelletization. In normal operations, PVC has a VCM content of less than 1 part per million, Other production processes, such as micro-suspension polymerization and emulsion polymerization, produce PVC with smaller particle sizes (10 μm vs. 120-150 μm for suspension PVC) with slightly different properties and with somewhat different sets of applications. The product of the polymerization process is unmodified PVC. Before PVC can be made into finished products, it almost always requires conversion into a compound by the incorporation of additives such as heat stabilizers, UV stabilizers, lubricants, plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, flame retardants, biocides, blowing agents and smoke suppressors, and, optionally pigments.

http://img.informer.com/wiki/mediawiki/thumb.php?f=PVC-polymerisation-2D.png&width=40

Low alloy steel: In the research it was found that the properties were similar to stain less steel and the low alloy steel used in the mouse was with same properties as used in the mouse ball.

Rubber material (Coating over metal Ball)

Materials used are:

1) Polyurethane

2) ABS

3) Polyester

4) Cellulose polymers(CA)

5) Polystyrene

Polyurethane: Polyurethane is rubber based material which is bounded on stainless steel of the mouse, the mouse is in circle shape and that is ripped off with polyurethane Polyurethanes, are most commonly known as polycarbamates, they belong to a larger class of compounds called polymers. Polymers are macromolecules which are made up of smaller. The repeating units known as monomers, they are attached with side groups which consist of a primary long chain back bone molecule. Carbamate groups characterize the Polyurethanes (-NHCO2) in their molecular backbone.

By reacting monomers in a reaction vessel, Synthetic polymers, like polyurethane, are produced In order to produce polyurethane, a step—also known as condensation—reaction is performed. In this type of chemical reaction, the monomers that are present contain reacting end groups. Specifically, a diisocyanate (OCN-R-NCO) is reacted with a diol (HO-R-OH). The first step of this reaction results in the chemical linking of the two molecules leaving a reactive alcohol (OH) on one side and a reactive isocyanate (NCO) on the other. These groups react further with other monomers to form a larger, longer molecule. This is a rapid process which yields high molecular weight materials even at room temperature. Polyurethanes that have important commercial uses typically contain other functional groups in the molecule including esters, ethers, amides, or urea groups.

Manufacturing process for the extraction of polyurethane http://www.niir.org/g/c/ni-173/11.jpg

References:

1) Granta Design Limited, Cambridge, (2009)(www.grantadesign.com), CES EduPack User Guide

2) Ashby, M.F. (2005) "Materials Selection in Mechanical Design", 3rd edition, Butterworth-Heinemann, Oxford, UK , Chapter 16.

3) http://www.gdrc.org/uem/lca/lca-define.html

4) Baer, E., "Advance polymer ,"Scientific American, Vol.225,No.4,Oct 1896.

5) Engineered materials Handbook ,Vol 2 , Engineering Plastics, ASM international ,Materials Park,OH,1988

6) R.J., and P. Lovell , Introduction to polymers, 2nd edition ,chapman and Hall , New York , 1991.

7) Billmeyer , F.W..Jr.,Text book of Polymer science,3rd edition, Jhon Wiley & sons , New York ,1984 . Chapter 11.

8) Kingery , W.D.,H.K.Bowen ,and D.R, Uhlmann,Introduction metals, 2nd edition ,jhon Wiley & sons ,New York ,1976 Chapter 14 and 15.

9) Gordon , P., principles of phase diagrams in materials systems, McGraw - hill Book company new York ,1986.

10) "Cambridge Engineering Selector v4,Granta Design Limited , Cambridge, UK,2005."

11) "Cebon,D.Ashby,M.F. and Lee-Shothaman,L.'CES Edupack 2009 user's Manual ' , 1, Granta Design limited, Cambridge, UK,2005."

12) ABS - acrylonitrile butadiene styrene On Designsite.dk, lists applications. Retrieved 27 October 2006.

13) Ed., Time-Life Books. Input/output Understanding Computers. Alexandria, VA: Time-Life Books, 1990

14) Alexander, Howard. "Behold the Lowly Mouse: Clever Technology Close at Hand.

15) N.A. Hart. 2009. Course documents on sustainable design and manufacture. Available online from: http://blackboard.staffs.ac.uk/webapps/portal/frameset.jsp?tab=courses&url=/bin/common/course.pl?course_id=_5182_

16) copper and its uses" on

http://www.ganapati engineering.com [accessed on 2010]

17) "Copper a vital element" on

http:// resources .school sciences .co.uk [accessed on 2009]

18)"Why is stain less steel stain less" on

www.science direct.com

19) Manufacturing process of stainless steel "on

www.industrialmetalcasting.com/pdf/ss-mfg-process.

20) "polyurethane "on

http://www.enotes.com/how-products-encyclopedia/polyurethane

21)Lockton, D., Harrison, D.J., Stanton, N.A. 'Making the user more efficient: Design for sustainable behaviour'. International Journal of Sustainable Engineering Vol.1 No. 1, pp. 3-8, March 2008)

http://www.danlockton.co.uk/design-for-sustainable-behaviour/

21)

22) Journal of Occupational and Environmental Medicine: February 2010 - Volume 52 - Issue 2 - pp 163-168

LIFE CYCLE ASSESSMENT:

LCA is a holistic tool used to identify the environmental consequences of a product, process or activity through its entire life cycle and to identify opportunities for achieving environmental improvements. Life cycle stages include:

ü Raw materials acquisition,

ü Manufacturing,

ü Use/reuse.

ü Maintenance.

ü And recycling/waste management.

Taking as an example the case of computer mouse an LCA involves making detailed measurements during the manufacture of the product. LCA information is to be taken into consideration is at the design stage of new products.

LCA approach consists of four interrelated components:

Goal definition and scoping: definition of the study purpose and objectives, identification of the product, process or activity of interest, identification of the intended end-use of study results and key assumptions employed.

Inventory analysis:

Identification and quantification of raw materials and energy inputs, air emissions, water effluents, solid waste, and other life-cycle inputs and outputs.

Impact assessment:

Qualitative and qualitative classification, characterization and valuation of impacts to ecosystems, human health and natural resources, based on the results of a life-cycle inventory.

Improvement assessment:

Identification and evaluation of opportunities to achieve improvements in processes that result in reduced environmental impacts, based on the results of an inventory analysis or impact assessment.

LCA gives the entire cradle to grave activities of a product or process i.e from processing of raw materials to transportation, extraction, in addition to reviewing the issue of material re-use and final disposal. As a system LCA identifies processes and potential environmental burdens throughout a products life cycle.

The term life cycle refers to the holistic assessment which requires the assessment of raw material production, manufacture, distribution, use and disposal including all intervening transportation steps.

LCA method is one of the official methods for environmental evaluation. It recognises that every product has impact on the environment during all phases of its life and it has started a system, where each new product standard is attached with a temporary environmental annex. For in this regard life cycle assessment is a central tool.

The LCA method can be divided into three basic steps

Goal and scope definition

Inventory analysis

Impact assessment

The first step in the LCA method is the goal and scope definition. For the scope the following items should be clearly described

LCA is a technique that allows the comparison of the environmental impacts of materials and products. This assessment provides quantitative data to identify the potential environmental impacts of the material or product on the environment. LCA is common for assessments to be made of more limited periods eg. Cradle-to-gate and cover the entire life cycle life cycle of a material.

The entire analysis is referred to as cradle-to-cradle which refers to production from extraction of raw materials, production and delivery and is often broken down into phases of lesser ambition.

Goal definition and scoping is the most critical component of LCA because it provides a frame of reference for the entire study and helps define interrelationships among the other three LCA components; inventory analysis, impact assessment, and improvement assessment. The goal definition identifies the overall purpose for the LCA and its intended applications. Goal definition and scoping initiates the LCA and then drives the scope, boundary settings, data categories and data needs. This process is continuously revisited during an LCA. Scoping defines the boundaries, assumptions and limitations and should be done before an LCA is conducted to ensure that the breadth and depth of analysis are consistent with the defined goal of the LCA.

Inventory Analysis:

It is the most well-developed component of LCA. A completed inventory analysis provides an overview of the life-cycle inputs and outputs associated with a particular system. The results of an inventory analysis may be used to identify areas to achieve improvement, as baseline information for conducting an impact assessment or some combination of the two. This analysis gives the boundaries of the system to be studied and develop a data questionnaire to collect the appropriate data. Develops stand alone subsystem data and conduct a peer review to validate the results.

ABS

Acrylonitrile -butadiene-styrene is an amorphous polymer consisting of the three monomers (A,B,S) offer flexibility in which acrylonitrile provides chemical resistance, ageing resistance, hardness, rigidity, gloss and melt strength .Butadiene provides low temperature ductitlity,flexibility and melt strength. Styrene provides processing ease, gloss and hardness.

The main disadvantages of ABS are its poor solvent and fatigue resistance poor UV resistance, unless protected and maximum continuous use temperature is only around 70 degree centigrade.

Phenolics;

Phenolic resins are obtained by polymerization and in the preparation of phenolic resins, the mode of catalysis of the resulting resin indicates the overall property characteristics.

The phenolic resins have the following features:

1. These resins have excellent thermal behaviour

2. High strength level

3. Mechanical stability

4. Thermal stability

5. Low toxicity

6. Electrical and thermal insulating capabilities

7. Good cost performance characteristics

8. Low heat transfer

9. Excellent flammability performance

As these properties are unique and valuable, they are among the most important thermo sets. For many years Phenolics have been used as general non reinforced thermo set plastics in applications such as electrical switches , computer peripherals etc.. These phenolic resins have high crosslink densities so they are quite brittle and have high shrinkage.

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