Plastic Injection Moulding - A Detailed Overview The history of injection moulding dates back to around 19th century. Ever since the invention of the injection, mouldingmachines have undergone several modifications to attain the formwidely used today. Initially, the injection moulding methods werebased on the die casting technology where immense pressure was applied to obtain the desired shapes. The plastic injection manufacturing became widely popular after the Reciprocating Screw moulding machine acquired the patent rights in 1956. Raw MaterialsThere are several kinds of raw materials used for the manufacturing of the plastic injections. However, the thermosetting plastic, elastomers and thermoplastic polymers (resins) are widelyused in the production process due the presence of greater viscosity in these materials.
Equipment The Plastic injection moulding machines have basic component parts such as material hopper, heating unit, plunger etc. Thesemachine parts are used to build pressure and keep the moulds inproper order to give the perfect shape once the molten material is poured inside it. They are also called presses, working inaccordance with the tonnage ratings. Tonnage is the capability of the machine to exert clamping force during the manufacturingprocess to keep the moulds in closed position. The tonnage may range between 5 tons to more than 9000 tons depending upon the rigidity of the raw materials and the projected area of the moulding parts.
Plastic Injection Moulding Melting Polymers: There is a broad and cylindrical melting unit in theinjection-moulding machine, where the polymer is converted into liquid underhigh temperature and pressure. The polymer is filled in an auger, which has an opening at the bottom. The auger is introduced into the melting unit using a hydraulic motor. A valve system at the bottom of the cylinder restricts the passage of the liquid into moulds. Pouring the Liquid Material into the Moulds Once the heating process is over, the auger is pushed further to pour theliquid polymer in to the moulds to give the requisite shape to the injections.The moulds are compressed under huge pressure to keep them intact and in proper position. During this process, the liquid is poured twice or more to ensure there are no air spaces left.
Cooling After the moulding, the entire mould is introduced to cooling for compact solidification of the plastic injections, which consumes the major time-period during the entire manufacturing process. The cooling is done bypassing air or water over the heated moulds or introducing cold water through small holes on the mould surface.
De-moulding Once the cooling process is over, the compact plastic injections are ready for removalfrom the moulds. The clamp on the mould is unlocked to open the mould and derive the injection. The entire process is completed and the mould is now ready for the next unit manufacturing. Plastic injections are affordable compared to other forms of injection. The cost of production mainly depends on the type of machineries. In the long run, this is alucrative business. The plastic injection moulds are widely used in the manufacture of a number of other plastic products. Please visit our website for more information on our services pertaining to plastic injection moulding.