Economic Considerations in Engineering Design

Recycling Issues with Material Usage

Factors Effective in Material Selection in Engineering Design

Design limiting material properties

– Economic CostRecyclability

– General Density

– Mechanical Elastic moduliStrengthHardness Fracture toughness / Fatigue Damping capacity

– Thermal Melting point / glass transition TThermal conductivity / diffusivity / expansionSpecific heat / shock resistance

– Electrical Conducting / non conducting

– Environmental Corrosion / oxidation / wear

Economic Considerations• Economics of engineering

a component / system depends on three factors: – component design – material usage – manufacturing costs.

• Stages in Component/Product Designing– Conception– Designing– Material Selection– Manufacturing Method

Iterative Process--- Less the no. of iterations, less the cost.

Based on• Properties• Cost

Usually a family of materials is selected that satisfy the design constraints. Then comparisons are made on the basis of cost per unit. This cost also includes unavoidable material wastage during manufacturing stage.

Cost Included in Manufacturing • After design and material selection, it is

up to manufacturing method to reduce the product cost.

• Usually manufacturing includes both primary stage and secondary stage.

• The cost considerations include the – capital on tooling– maintenance cost– labor– repair costs– material wastage.

• More the number of manufacturing stages, higher will be the product cost.

• Inspection, assembly, and final packaging will add-on to the product cost.

Materials selection requires:

Design and identification of key material properties

Filtering – 50,000-80,000 materials available– new materials being developed

all the time.

Case study of a Vacuum Cleaner:

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Age, Power, Weight and Cost of Vacuum Cleaners :

Cleaner Material Power Weight Cost

Hand,1900

Wood,canvas

50 W 10 Kg $270

Cylinder,1950

Mild Steel 300 W 6 Kg $110

Round,1965

Mild Steel 450 W 5.5 Kg $100

Cylinder,1987

poly-propylene

800 W 4 Kg $60

Recycling of Materials

Material Life Cycle

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