The gas internal pressure injection moulding (short GID) is in principle a normal injection moulding with the difference that toward end of the tool filling phase after defined partial filling of the cavity an inert gas (usually nitrogen) is injected.
The gas displaces the melt, takes over with pressures up to maximally 300 bar the remainder filling. From melt displacement cavities result. Injecting can take place via the machine nozzle and thus via the dead head system or via a separate Injektionsnadel directly into the shaped part in the cavity. A further variant is the complete filling of the cavity with melt and following blowing out of melt in a or the into the snail cylinder.
In this way partially or altogether thick-walled parts without idea places with good surface quality can be manufactured economically. Shorter cycle times with fewer materials with often reduced closing force are reached. The purposeful cavitation, which must be already considered with the shaped part construction, increases the rigidity of the shaped parts and makes interesting Design variations possible in relation to the normal injection moulding. The processing possibilities do not only extend to thermoplastic molding materials. The procedure is applicable for almost all molding materials with source river behavior. This applies to most thermoplastics, a large number of thermosetting polymers and also many elastomers.
As supplementing procedure also the water internal pressure injection moulding (WID) gives.
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