Environmentally Conscious Design & Manufacturing

Environmentally Conscious Design & Manufacturing (ME592)

Date: April 10, 2000 Slide:1

Environmentally Conscious Design & Manufacturing

Class 16: Material Selection

Prof. S. M. Pandit



Agenda

• Generic automobile materials• Engineering materials• Properties of materials• Guidelines for materials selection• Steels, cast iron, alloys, and

ceramics



Generic Automobile Materials



The Flow of Aluminum Unit: kg



Materials Use in Automobile

Unit: kg



Design ProcessProduct Function?Need for a device

or productSynthesis

(Creativity-Ideas)

Material selection

Product part(prototype)

Put Partinto Service

Redesign

Change • material?• process?

UnsatisfactoryEvaluate

performance

Satisfactory



Engineering Materials• Ferrous metals: carbon, alloy, stainless, and tool and

die steels• Nonferrous metals and alloys: aluminum, magnesium,

copper, nickel, titanium, low-melting alloys• Plastics: thermoplastics, thermosets, and elastomers• Ceramics: glass ceramics, glasses, graphite, and

diamond• Composite materials: reforced plastics, metal-matrix

and ceramic-matrix composites, and honeycomb structures.



Engineering Materials (cont.)

High modulusAbrasion resistant

MetalsPoor corrosion Resistance

Ceramicsbrittle

GlassesBrittle

Elastomerscreep at low temp

Polymerscreep at low temp Composites

Corrosion resistant Corrosion resistant

Low modulusHigh strength

High strength, Moderate modulus, High ductility



Properties of Materials

• Mechanical properties:strength, toughness, ductility,hardness, elasticity, fatigue, and creep

• Physical properties: density, thermal expansion, conductivity, specific heat, melting point, and electrical and magnetic properties

• Chemical properties:oxidation, corrosion, toxicity,and flammability

• Manufacturing properties: castability, formability, machinability, weldability, and hardenability by heat treatment.



Properties of Materials (cont.)

ProductionComposition Recycling

Energy Effluents

Resource depletion

Environmental Aspects



Guidelines for Materials Selection

Traditional guidelines for materials selection:

• Desired mechanical, physical, and chemical properties

• Shapes of commercially available materials• Reliability of supply• Cost of materials and processing



Guidelines for Materials Selection (Cont.)Guidelines for materials selection from the

ECDM viewpoint:

• Choose abundant, non-toxic, nonregulated materials

• Choose materials familiar to nature• Choose easily recycled materials• Minimize environmental impact without loss

of product quality



Low-Impact Materials

Non-hazardous materials Non-exhaustable/renewable materials Low-energy content materials Recycled and recyclable materials



Energy Aspects

• Energy to mine raw materials• Energy to extract and refine ore• Energy to from product• Energy to ship product• Energy to use product• Energy to disposal of product



Part is remanufacturable – Example: starter, transmission

Steel, aluminum, lead, and copper have good recycling records.

Organic material for energy recovery, that cannot be recycled. Example: Tires, rubber in hoses.

Inorganic material with no known technology for recycling.

Material Recyclability



• Types of recycled material–home scrap–pre-consumer–post-consumer

• Design considerations–ease of disassembly–material identification–simplification and parts consolidation–material selection and compatibility

Material Life Extension



Improvements of Existing Products

• Substitution (water based coatings instead of volatile organic compounds)

• Reformulation (e.g., unleaded gasoline is a reformulation of the leaded variety)

• Elimination



Reduced Material Intensiveness

• Dematerialization- Less materials means less consumption, saves energy and money.

• Shared use of product• Integration of functions• Functional optimization of product and

components



• Weight reductions reduce energy needed to move the product.

• Avoid over-dimensioning the product via good design

• Reduction in volume (space required for transport and storage)

Reduction of Material Usage



Example (Xerox)

Source: Calkin, P., 1998



The Results of Efforts

• Reduced solid waste generation by 73 percent• Increased the factory recycle rate by 141

percent• Reduced releases to the environment by 94

percent• Realized over $ 200 million in annual savings



SteelsPlain carbon steels• Low-carbon steel (0.02% - 0.3%C), used for manufacturing

bolts and nuts, bars and rods• Medium-carbon steel (0.3% - 0.6 %C), used to harden tools

such as hammers, screw drivers, and wrenches.• High-carbon steel (0.6 % - 1.5%C), for edge cutting tools

such as punches, dies, taps, and reamers.

Alloy steels• Addition of alloying elements (Cr, Mn, Mo, Ni, T, V)

improves mechanical properties of steels



Cast Iron•Alloy of iron and carbon (1.7%-4.5%C)•Gray cast iron, used in machine tool, automotive, and other industries•White cast iron, used for the production of malleable iron casting•Chilled cast iron, used for products with wear-resisting surface•Alloy cast iron, used in automotive engine, brake, and other systems, machine tool casting, etc.•Malleable iron castings, used in industrial applications that require a highly machinable metal, great strength ductility and resistance to shock.



Aluminum and its AlloyProperties:• High strength-to-weight ratio • Resistance to corrosion• High thermal and electrical conductivity• nontoxicity, ease of recycling• reflectivity, ease of machinability

Uses:• Con and foil• Construction (building etc.)• Transportation (aircraft, automobile, etc.) • Electrical conductors, and appliances



Nonferrous Alloys• Copper-based alloys (ex. Brasses and bronzes)

- good strength, hardness, conductivity. • Aluminum-based alloys

- increased tensile strength, weldability, ductility

• Nickel-based alloys- high strength and corrosion resistance

• Zinc-based alloys- good corrosion resistance, strength, and ductility



Ceramics• Types

Oxide ceramics, carbides, nitrides, cermets, sialon

• General propertiesBrittle, high strength, high hardness, low toughness, low density, low thermal expansion, and low thermal and electrical conductivity

• ApplicationsAutomobile components, electronics, cutting tools, fiber optics

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