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Material Science and Materials Processing (Day 1) Engineering CAD Mr. Richards. What are the Three Classifications of materials?. Material Classifications. Natural materials: Occur in nature Organic: wood, cotton, hemp Inorganic: stone, clay, metals Synthetic:

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material science and materials processing day 1 engineering cad mr richards
Material Science and Materials Processing

(Day 1)

Engineering CAD

Mr. Richards

material classifications
Material Classifications
  • Natural materials:
      • Occur in nature
        • Organic: wood, cotton, hemp
        • Inorganic: stone, clay, metals
  • Synthetic:
      • Human-made: rubber, plastics, nylon, Teflon
  • Mixed materials:
      • Combination of natural and synthetic: plywood, paper…etc.
types of materials close up
Types of Materials (Close-up)
  • Woods (Natural & Engineered)
  • Metal
  • Plastics
  • Ceramics
  • Composites
types of materials close up1
Types of Materials (Close-up)

Woods

    • Thickness of cell walls determines density.
    • Color is a function of the chemicals in its cell walls.
    • Grain is the way wood fibers grow.
  • (Engineered):
    • Made by combining particles and fibers of wood with adhesives: wood chips, plywood.
    • Advantages: more strength per pound
types of materials close up2
Types of Materials (Close-up)

Metal:

    • Structure determines properties
    • Good conductors of electricity and heat
    • These are factors that might influence material selection.
  • Categorized as:
    • Ferrous:
      • Contain iron: steel
    • Nonferrous:
      • Do not contain iron: aluminum
types of materials close up3
Types of Materials (Close-up)

Plastics:

    • Can be made into films, fibers, and solids; molded into a variety of products and shapes.
    • Most plastics are made from petroleum.
    • Plastics are polymers. Have an enormous amount of uses.
    • Have densities less than metals, greater than most woods, and similar to crude oil. (material selection)
  • Categorized as:
    • Thermoplastic:can be softened by heat, then hardened again by cooling.
    • Thermoset:cannot revert once heated and molded.
types of materials close up4
Types of Materials (Close-up)

Ceramics: (material selection)

  • Made from clay and nonmetallic inorganic materials
  • Have an atomic structure that forms a 3-D geometric shape
    • Compounds formed by combinations of metallic and nonmetallic elements
  • High melting points; high strength and hardness; resistant to wear; brittle; can be transparent, translucent, or opaque; low densities
  • Sometimes a better choice then metal because it tolerates heat well and is an electrical insulator.
types of materials close up5
Types of Materials (Close-up)

Composites:

    • Combination of two or more materials with different properties
    • Materials retain separate identities
    • Formed by using materials of two types:
      • Matrix material
      • Reinforcement material (fiber)
    • Often lighter and provide similar or greater strength applications
    • Cost of manufacturing is significantly higher.
    • Often used in decks because it is resistant to rotting and insect damage.
  • Categorized into three matrix types:
    • Polymer, metallic, and ceramic
properties of materials
Properties of Materials

Key ideas:

  • Materials are chosen based on properties that make them appropriate for particular applications.
  • Categories:
    • Physical, mechanical, electrical, chemical, magnetic, thermal, optical, and acoustic.
properties of materials1
Properties of Materials

Mechanical:

  • Those that influence a material’s ability to endure and withstand applied forces
  • Mechanical Testing:
    • Strength
    • Hardness
    • Ductility
    • Elasticity
    • Plasticity
    • Malleability
    • Brittleness
    • Toughness
    • Yield Point
slide14

Elastic limit (yield strength)

  • Beyond the elastic limit, permanent deformation will occur.
  • The lowest stress at which permanent deformation can be measured.
  • Under repetitive stresses, cracks in a metal can develop and grow and cause failure even thought the elastic limit has not been reached.
properties of materials2
Properties of Materials
  • Strength (forces):
  • Flexural
slide16

Failure of Materials

  • Buckling occurs when a given material is compressed until it gives way and collapses
properties of materials3
Properties of Materials

Physical properties:

  • Density and freezing, melting, and boiling points
    • Density is a measure of how tightly atoms are packed together
    • Freezing, melting, and boiling points exist on a temperature continuum
properties of materials4
Properties of Materials

Electrical properties:

  • Conductivity and resistivity

Magnetic properties:

  • Diamagnetic, paramagnetic, or ferromagnetic

Thermal properties:

  • Ability to conduct heat and expand when heated

Optical properties:

  • Ability to reflect, absorb, refract, or transmit light
material science and materials processing day 2 engineering cad mr richards
Material Science and Materials Processing

(Day 2)

Engineering CAD

Mr. Richards

processing materials
Processing Materials

Key ideas:

  • The term “processing” means transforming basic (raw) materials into industrial materials, and then into finished products.
  • Processing methods are categorized according to:
      • Mass change
      • Phase change
      • Structure change.
      • deformation of material
      • Consolidation of material

**Example: Processing trees into timber**

processing materials cont d
Processing Materials (cont’d.)

Mass change:

  • Cladding
  • Electroplating
  • Drilling
  • Sawing
  • Grinding
  • Turning

Phase change:

  • Casting
  • Pressing
  • Injection molding
  • Blow molding
  • Vacuum forming
  • Rotation molding
processing materials cont d1
Processing Materials (cont’d.)

Structure-change:

  • Hardening
  • Annealing
  • Tempering
processing materials cont d2
Processing Materials (cont’d.)

Deformation:

  • Forging
  • Rolling
  • Machine pressing
  • Extrusion
  • Drawing

Consolidation:

  • Fastening
  • Joining
  • Sintering
  • Composite materials
  • Coating
slide24

Processing Materials (cont’d.)

  • Example Processes:
  • Injection Molding:(Very Accurate) common industrial process used to manufacture parts.
  • Extrusion:process whereby a continuous stream of a product is made by squeezing softened material (just below its melting point) through a small opening called a die.
slide25

Processing Materials (cont’d.)

  • Example Processes:
  • Sintering:is a process where powdered materials are combined with a binding material and pressed into shapes in a mold under heat and high pressure.
factors in selecting materials
Factors in Selecting Materials

Key ideas:

  • Materials are chosen based on their properties, as well as other factors.
  • Choice of material often reflects trading off competing benefits.
  • True costs of materials extend beyond the cost of the raw material itself.
factors in selecting materials cont d
Factors in Selecting Materials (cont’d.)

Properties determine suitability for applications:

  • Cost
  • Safety
  • Availability
  • Disposability
  • Environmental impact
factors in selecting materials cont d1
Factors in Selecting Materials (cont’d.)

True cost of a material includes:

  • Cost of the raw material
  • Amount of energy and water needed
  • Amount of pollution generated
  • Human time and effort wasted
factors in selecting materials cont d2
Factors in Selecting Materials (cont’d.)
  • Availability of materials is a primary.
  • Safety is also important.
  • Disposability and environmental impact drive decisions about materials.
    • Some materials can biodegrade.
    • Engineers also consider the energy it takes to process materials.
factors in selecting materials cont d3
Factors in Selecting Materials (cont’d.)

Figure 4.70 Comparison of cost versus strength for structural materials.