Pages 72-75

Pages 72-75

1. Different types of moulding

   • Injection moulding
     • Process of using melted plastic and forcing it into the mold
     • Plastic pellets are heated by a screw drive putting them through a heater
       • The plastic the melts and it is pumped into a mold to cool and solidify it is then removed
     • This method is very popular in industry production such as the manufacturing of toys
   • Blow moulding
     • A long plastic rod called a parison is put into a mold which is clamped around the plastic and secured by the top and bottom
       • It is then extruded to the right length
         • Air is then forced into the top of the hollow rod expands the rod to fit the mold
           • It is then left to cool and solidify before being removed.
     • This is used to make hollow objects such as PET bottles
   • Rotational moulding
     • A piece of plastic is placed into a mold and heated up
       • When melted the mold rotates rapidly
         • The plastic then sticks to the edges of the mold and it is left to cool before removed

2. A range of different forming techniques

   • Vacuum forming
     • Plastic is heated and then brought down over mold
       • A vacuum sucks the air out and pulls the plastic over the mold
         • The pressure is then released after it has cooled and product is removed
   • Drape forming
     • Clay or pastry is put over a mold
       • It is then patted down and left to rest
         • When hard it is taken off the mold
   • Compression moulding
     • Two molds sandwich a piece of plastic to take the shape of the molds.
   • Forging
     • Hand forging
       • Hot metals are bent and changed through someone shaping it with tools
     • Shaping a material through compression forces
   • Extrusion
     • When raw plastics are melted and forced through a flat mold to take a certain shape and profile