Materials, Manufacture, Processes and Practices

Materials, Manufacture, Processes and Practices

1. Plastics

   • Electrical insulators
   • High impact polystyrene (HIPS) - Light flexible and strong - can be vacuum formed
   • Acrylic - Hardwaring and will not shatter - Easily cracks and scratches - Used in airplane windows, car light covers

2. Timbers

   • Softwoods
     • Pine
   • Manufactured boards
     • Plywood - Odd numbers of thin layers of wood glued together
     • MDF - used for making moulds

3. Smart materials

   • Piezo transducer - Produces small voltage when deformed by mechanical movement
   • Smart cable - Converts mechanical energy to electrical energy
   • Solar cell - Converts light to electricity
   • Optical fibre - Glass that carries light signals - used in communications
   • Thermocolour sheet - Changes colour when heated
   • Liquid Crystal display (LCD) - Used to show numbers or text - When crystals are passed current it changes shape and absorbs light so the crystals seem darker
   • Smart wire - Shortens in length when a small current is passed through it - returns to original shape when applied with heat
   • Quantum tunnelling composite - Flexible polymer - changes from insulator to conductor when compressed

4. Metals

   • Mild steel - Tough ductile and malleable - Strong and is used for engineering parts
   • Aluminium - Light and tough - Used for bikes, vehicle frames and aircrafts

5. Processes

   • Injection moulding - Plastic material in the form of granules is melted until soft enough to be injected under pressure to fill a mould.
   • Vacuum forming - Sucking heated plastic onto the shape of a mould
   • Line bending - Line bending involves heating the material along a line, using a heating element. The plastic softens as it heats, allowing it to be bent.
   • Laser cutting - focused laser beam is used to melt material in a localised area
   • Rapid prototyping - Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design
   • Milling - Machine used to print PCB boards

6. Manufacture machines

   • Photo Etch
     • Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design
   • Milling
     • Machine that drills tracks onto a copper board - Prints PCB circuit

7. Manufacture

   • One off production - One product made at a particular time - may be a prototype - Takes longer to make
   • Batch production - Series of identical products made in small or large quantities
   • Mass production - Product goes through various stages on the production line - usually involves the product being produced for days or weeks in large numbers - Eg a car
   • Continuous production - Product is continually produced over hours days or years - Eg screws
   • Just in time production - Component parts are ordered and arrive at the time the factory needs it - Less storage needed - If supply is stopped production stops