Resistant Materials

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Mechanical Properties

  • Bending: is the ability for a material to withstand forces which are attempting to bend it
  • Compression: is the ability for a material to withstand forces that are trying to crush or shorten it
  • Shear: the materials resistance to forces sliding in the opposite direction
  • Tension: the materials resistance to forces pulling in opposite directions
  • Torsion: the materials ability to withstand twisting forces
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Woods

  • Hardwoods: wood mde from deciduous trees that loose their leaves, eg - Oak, Beech, Ash
  • Softwoods: wood made from conifer trees which are evergreen, eg - Pine, Cedar
  • Conversion means taking the trunk of the tree and sawing it into usable planks, there are 2 methods - through-and-through sawing and quarter/radial sawing
  • Through-and-through is the quickest, cheapest, easiest method of conversion and can produce planks of various thickness
  • Quarter/radial is more expensive as the log must be cut into quaters and there can be some waste wood, but it produces stronger and more attractive timber
  • (http://www.trada.co.uk/techinfo/library/view/A518F722-0978-4D95-976F-2B1BC1EFC4B7/Solid+Timber%3A+Sections+and+Sizes/sawing.jpg)
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Manufactured boards and Veneers

  • Manufactured boards are made by converting logs into a variety of forms (wood chips from waste) and then gluing them together to make sheet materials
  • Manufactured boards can be coated with veneers to make them look like real wood, there are 2 ways of cutting logs into veneers: rotary cutting and slice cutting
  • Rotary cutting acts like a pencil sharpener, it produces a continuous roll of veneer that is then cut into sheets
  • Slice cutting produces flat sheets of veneer which usually have an interesting grain so are used for decoration
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Metals

  • Alloys: metals formed by mixing two or more metals to produce a new metal that has improved characteristics or properties
  • Ore: a solid, natural material from which from which metal can be extracted
  • Ferrous: group of metals that contain iron and varying amounts fo carbon, normally magnetic
  • Non-Ferrous: group of metals that dont contain iron
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Plastics and Composites

  • Plastics: - thermoplastics: plastics that can be reshaped when reheated 

                   - thermosetting plastics: plastics that can not be reheated

  • Composite materials are produced when two or more materials are combined: - GRP (glass reinforced plastics) and Carbon fibre reinforced plastics
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Smart and Modern materials

  • Smart materials are materials that have reactive capability, their physical properties change when they influenced by something else
  • Polymorph: a substance that can take different forms when heated

    Thermochromic: having the ability to change colour when the temperature is varied (eg, heat         sensitive baby spoons)

    Shape memory alloys: can change their shape when heated (eg memoflex specticles that             return to their original shape even when badly bent)

    Nanotechnology: involves altering a meterials properties by changing the individual atoms that       form the materials, so materials are now made stronger, lighter, stiffer than ever before

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Sustainability

  • Sustainability: the ability to keep making or using a product without excessive damage to the environment
  • 5 Rs: reduce, reuse, recycle, refuse, replace, rethink
  • Designer/manifacture's responsibility, designers and manifacturers can help make a product sustainable: - using renuable materials

                       - using fewer materials

                       - using materials that require less energy in manifacture

                       - enabling products to be repairable

                       - improving recycling oppertunities for the product

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The 5 Rs

  • Reduce: Customers need to look to reduce the number of products they buy, or buy products that use less energy. Manufacturers are looking to design products that have fewer materials in the product, takes less energy to manifacture and needs less packaging for transport
  • Reuse: Costumers need to look to reuse suitable products (eg glass milk bottles). Manufacturers need to try and design the product that can be dismantled at the end of its life so some parts can be reused
  • Recycle: Costumers need to recycle as many suitable products as possible. Manufacturers need to make products where recycling them or some of their parts is possible
  • Refuse: Costumers have the oppertunity to choose whether to buy a product, Do I really need this? Are their other products that do the same job but more efficiently? 
  • Repair: Designers have a responcibility to make a product that can be repaired more easily, it takes fewer resources to replace a part than replace the whole thing
  • Rethink: Costumers can ask questions such as, Do I really need this product? Can I do things differently? Manufacturers can make a product that can do the same job but more efficiently
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Tools

  • Coping saw: wood, plastics
  • Tenon saw: wood
  • Hacksaw: metals and plastics
  • Wood chisel: wood
  • Cold chisel: metal
  • File: metal, plastics
  • Plane: wood
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Vacuum molding

  • The mould is placed inside the machine and the plastic sheet is clamped to the top of the box using the toggle clamps. The heater is them moved into position to heat the plastic until it softens. The material will begin to sag under its own weight and will appear rubbery.
  • The heater is pushed back and the mould, is then raised into the hot plastic before the vacuum pump is truned on
  • The air between the mould and the softened thermoplastic is sucked out by the pump. The plastic will be forced over the mould creating a shape
  • The sheet is unclamped and the mould is removed
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