Plastic Forming and Plastic Injecton Moulding
Plastic forming
There are two types of plastic. One is called thermosettting resin which does not soften agina once it is formed and hardened, and other is called thermoplastic resin which becomes soft or hard when its temperature rises or falls. Although thermosetting resin has an older history, the majority of the presently used plastic are made of thermoplastic resins.
There is plastic forming method :
Plastic injection moulding process
(1) In general ,material arrangement and coloring are carried out in separate process.
(2) The drying process may be required for some plastics but not required by others.
(3) Materials are supplied to a molding machine from a Hopper .
(4) Materials are heated to be plasticized with a heating cylinder. There are various methods for this process. The most popular method is as follows: the screw in-line feeds materials forwards while the screw itself goes rearwards, when a specified volume of plasticmaterial for plasticity is completed, the screw is moved forwards and a plastic resin is injection and charged into a closed die to mould a shaped.
(5) The resin that has filled up the inside of the cavity of die is cooled in the die and becomes solid.
(6) The die is opend to take out molded products. Parts other than products(supuremrunner, fin, defective products) which are produced by this process are regarded as non-conforming products and they can be used agina as moulding materials.