Samenvatting Manufacturing Engineering and Technology

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Samenvatting - Manufacturing Engineering and Technology

  • 0.6 Selection of Manufacturing Processes

  • The different categories of manufacturing methods are:
    • Casting
    • Forming and Shaping
    • Machining
    • Joining
    • Finishing
    • Microfabrication and Nanofabrication
  • The variations of Casting processes
    Expendable pattern, expendable mold, permanent pattern, permanent mold
  • The variations of Bulk-deformation processes
    Rolling, Forging, Extrusion and drawing
  • The variations of Sheet-metal forming processes
    Shearing, Bending and drawing, forming
  • The variations of Polymer-processing processes
    Thermoplastic, Thermosets, Rapid prototyping
  • The variations of Machining an finishing processes
    Machining, Advanced Machining, Finishing
  • The variations of Joining processes
    Fusion Welding, Other welding, Fastening and bonding
  • Types of production
    • Job shops
    • Small-batch production
    • Batch production
    • Mass production
  • 0.10 Manufacturing Costs and Global Competition

  • Typically the manufacturing cost of a product represents 40%
  • The total cost of manufacturing consists of the following components
    1. Materials
    2. Tooling 
    3. Fixed (rent etc)
    4. Capital (production machinery, equipment etc)
    5. Labor 
  • Outsourcing is defined as the purchase by a company of parts and/or labor form an outside source, either from an other company or another county, in order to reduce design and manufacturing costs.
  • Engineering materials 
    metals, platics, ceramics, composites and others
  • Behavioral manufacturing properties of materials
    Structure of materials, mechanical properties, physical and chemical properties, property modification
  • 1.2 Types of Atomic bonds

  • Atoms consist of Protons Neutrons and surrounding clouds or orbits of electrons
  • Negatively charged atoms are called anion
  • Positively charged atoms are called cation
  • There are basic types of atomic attraction associated with electron transfer, called primary bonds or strong bonds. Which bonds are there:
    • Ionic bonds (low ductility, low thermal and electrical conductivity)
    • Covalent bonds (high hardness, low electrical conductivity)
    • Metallic bonds (high thermal and electrical conductivity)
  • 1.3 The Crystal Structure

  • Atoms arrange themselves into various orderly configurations, called crystals; this atomic arrangement is called crystal structure or crystalline structure.
  • The following are the three basic atomic arrangements in metals:
    • Body-Centered cubic (BCC) 
    • Face-Centered cubic (FCC)
    • Hexagonal closed-packed (HCP)
  • All three arrangements can be modified by adding atoms of some other metal or metals, knows as alloying
  • The appearance of more than one type of crystal structure in metals is known as allotropism or polymorphism.
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Laatst toegevoegde flashcards

Design of parts to be cast need the following considerations
corners angles and section thickness
Flat areas
ribs
schrinkage
draft
dimensional tolerances
lettering and markings
finishing operations
What are the general design considerations for castings?
  • the part should be a easily cast as possible
  • select a casting process and a material suitable for the part.
  • locate the parting line of the mold 
  • design and locate the gates to allow uniform feeding
  • select an appropriate runner 
  • locate old features such as sprue screens and risers 
  • make sure proper controls and good practices are in place
There are three different types of molds these categories are:
  1. Expendable molds; typically made of sand, plaster of ceramics, and similar materials, and generally mixed with various binders.
  2. Permanent molds; mode of metals that maintain their strength at high temperatures
  3. Composite molds; made of two or more different materials such as sand, graphite and metal.
The different casting processes
see the picture
How can porosity be reduces or eliminated?
  • Adequate liquid metal should be provided to prevent cavities 
  • Internal or external chills
  • with alloys, porosity can be reduced or eliminated by high temperature gradients.
  • subjecting the casting to hot isostatic pressing is another method
What is porosity
may be caused by shrinkage, entrained or dissolved gases, or both. molten metal flows into the thicker regions that have not yet solidified. porous regions may develop at their centers because of contraction as the surfaces of the thicker region begin to solidify first.
There are 7 basic categories of casting defects, identified with boldface capital letters
  • A- metallic projections, consisting of fins, flash or projections, such as swells and rough surfaces. 
  • B- Cavities
  • C- Discontinuities, such as cracks or hot tearing, and cold shuts. 
  • D- Defective surface, such as surface folds, laps, scars, adhering sand ayers, and oxide scale.
  • E-Incomplete casting, such as misruns, insufficient volume of the metal poured and runout
  • F - incorrect dimensions or shape
  • G - inclusion, which forms during melting, solidification and molding.
Factors which you need to take into consideration:
  • Flow of the molten metal into the mold cavity, and design of gating systems or pathways for molten metal to fill the cavity
  • solidification and cooling of the metal in the mold
  • Influence of the mold material
What is a composite material?
It is a combination of two or more chemically distinct and insoluble phases with a recognizable interface, in such a manner that its properties are better than the two apart.
What is the difference between an elastomers and a rubber
an elastomer is defined as being capable of recovering substantially in shape and size after load has been removed;
a rubber is defined as being capable of recovering from large deformation.