تصنيع 1

• Manufacturing

  Latin words [manus (hand) + factus (make)] = made by hand
• Manufacturing processes


  A combination of machinery, tools, power, and labor
• Manufacturing processes


  • Technologically = application of physical and chemical processes (sequence of operations) to alter the geometry, properties, and/or appearance of a given starting material to make parts or products (multiple parts)
  • Economically = transformation of materials into items of greater value (changing their shape or properties)
• Examples of manufacturing processes


  • When iron ore is converted into steel, value is added
  • When sand is transformed into glass, value is added
  • When petroleum is refined into plastic, value is added
• Secondary industries


  Take the outputs of the primary industries and convert them into consumer and capital goods
• Manufacturing process


  A designed procedure that results in physical and/or chemical changes to a starting work material with the intention of increasing the value of that material
• Materials in manufacturing


  • Metals
  • Ceramics
  • Polymers
  • Composites
• Metals


  • Metals used in manufacturing are usually alloys, which are composed of two or more elements, with at least one being a metallic element
  • Pure iron has limited commercial use, but when alloyed with carbon, iron has more uses and greater commercial value than any other metal
  • Super-alloys are generally distinguished by their strength and resistance to corrosion and oxidation at elevated temperatures
  • Metallic properties include: high strength and stiffness, good electrical and thermal conductivity, and higher density than ceramics or polymers
• Methods to strengthen metals

  1. Alloying to form solid solutions and two-phase structures which are stronger than the elemental metals

  2. Cold working, in which the strain-hardened metal is stronger and harder than the unstrained metal

  3. Heat treatment - most of the commercial heat treatments are designed to increase the strength of the metal
• Types of metals


  • Ferrous metals (based on iron, includes steel and cast iron)
  • Nonferrous metals (other metallic elements and their alloys such as Al, Cu, Au, Mg, Ni, Ag, Sn, Ti, Zn)
• Steel

  An iron-carbon alloy containing 0.02% to 2.11% carbon. It is the most important category within the ferrous metal group. Its composition often includes other alloying elements as well, such as Mn, Cr, Ni, and Mo, to enhance the properties of the metal.
• Alloying elements in steel

  • C, Cr, Mn, Mo, and Ni increase hardenability during heat treatment
  • Cr and Mo improve hot hardness
  • Cr, Mo, V form hard carbides with C, which increases wear resistance
  • Vanadium inhibits grain growth during heat treatment which improves strength and toughness
• Cast iron

  An alloy of iron and carbon (2% to 4%) used in casting (primarily sand casting). Silicon is also present in the alloy (in amounts from 0.5% to 3%), and other elements are often added also, to obtain desirable properties in the cast part.
• Ceramics


  • High hardness, brittle, and no ductility
  • Electrical and thermal insulators, medium density (below the density of metals), high melting temperatures, and thermal expansion usually less than metals
  • Covalent and ionic bonding are the main atomic bonding which characterize the ceramics
• Types of ceramics


  • Traditional ceramics (based on clay, silica, Al2O3 and SiC)
  • New ceramics (carbides, nitrides)
• Polymers


  Compounds formed of repeating structural units called mers, whose atoms share electrons to form very large molecules. Polymers usually consist of carbon plus one or more other elements, such as hydrogen, nitrogen, oxygen, and chlorine.
• Types of polymers


  • Thermoplastic
  • Thermosetting
  • Elastomers
• Thermoplastic polymers


  Can be subjected to multiple heating and cooling cycles without substantially altering the molecular structure of the polymer. Common thermoplastics include polyethylene, polystyrene, polyvinylchloride, and nylon.
• Thermosetting polymers


  Chemically transform into a rigid structure on cooling from a heated plastic condition. Members of this type include phenolics, amino resins, and epoxies. Thermosets are more rigid, brittle, capable of higher service temperatures, and cannot be remelted.
• Elastomers


  Polymers that exhibit significant elastic behavior. They include natural rubber, neoprene, silicone, and polyurethane. Elastomers and thermosetting polymers are both cross-linked but Elastomers are lightly cross-linked, whereas thermosets are highly cross-linked.
• Composite material


  A materials system consisting of two or more distinct phases whose combination results in properties that differ from those of its constituents. The term phase refers to a homogeneous mass of material, such as an aggregation of grains of identical unit cell structure in a solid metal.
• Typical properties of composites

  • High strength-to-weight and stiffness-to-weight ratios
  • Good fatigue properties and toughness
  • Anisotropic properties in many cases
  • Other properties and features that are difficult or impossible to obtain with metals, ceramics, or polymers alone
• Categories of composites


  • Metal matrix composites (MMCs)
  • Ceramic matrix composites (CMCs)
  • Polymer matrix composites (PMCs)
• Reinforcing phase in composites

  • Fibers
  • Particles
  • Flakes
• Applications of high strength and light weight composites

  • Aircraft components
  • Car bodies
  • Tennis rackets
  • Fishing rods
• Applications of strong, hard, and high temperature resistant composites

  • Cemented carbide cutting tools