The gating system for vertical sand mold casting process must be dimensioned in such a way that the melt flows through it with as low turbulences as possible, that gases and ambient air are not trapped in the flow and that erosion of the sand mold does not occur during casting. The melt must also enter the casting cavity in a way which promotes direct solidification from the feeder neck up to the pouring basin. In addition to the above requirements, the gating system must also be economical; the amount of melt used in the system to feed the castings should be sufficient and minimal to achieve maximum efficiency whilst also producing quality castings. During mass production, casting defects such as gas and shrinkage porosity, cold shuts, slag inclusion, hot tears, burnt on sand, mould defects etc. can occur.
Nowadays, computer-aided simulations of casting and solidification are crucial for optimizing the parameters of the casting process and for predicting possible errors and risks before they actually occur. With them, we can determine the most optimal casting conditions already in the tool development phase and construct a suitable gating system, according to the specifications of the casting. This work describes the gating system optimization of insulator caps, made from white-heart malleable iron. To reduce the large number of ejected castings recorded in the company Livarna Titan, d.o.o. in Kamnik, a change was made on the modeling tools on the basis of “in-situ” thermal analysis and computer-aided calculations of casting and solidification using ProCAST software package.
The insulator cap, as a safety element on high-voltage transmission lines, has a required long service life and has to therefore be highly resistant against corrosion. Due to production difficulties in obtaining a suitable thickness of the zinc coating, further studies were carried out. The influence of the galvanizing process parameters and the microstructure of the malleable cast iron on the thickness and composition of the zinc coating was investigated using metallographic images and EDS analysis on a scanning electron microscope.
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