Abstract
Distribution of gasses to the cast volume and volume of pores can be maintained within the acceptable limits by means of correct setting of technological parameters of casting and by selection of suitable structure and gating system arrangement. The main idea of this paper solves the issue of suitability of die casting adjustment—i.e., change of technological parameters or change of structural solution of the gating system—with regards to inner soundness of casts produced in die casting process. Parameters which were compared included height of a gate and velocity of a piston. The melt velocity in the gate was used as a correlating factor between the gate height and piston velocity. The evaluated parameter was gas entrapment in the cast at the end of the filling phase of die casting cycle and at the same time percentage of porosity in the samples taken from the main runner. On the basis of the performed experiments it was proved that the change of technological parameters, particularly of pressing velocity of the piston, directly influences distribution of gasses to the cast volume.
Highlights
High pressure die casting (HPDC) allows production of thin-walled casts with high geometrical precision, with positive mechanical properties and with low price
The paper deals with the issue of advantages of change in setting of technological parameter in comparison to change in structure of gating system with regards to inner soundness of the cast
The obtained results have proved that the change in structure of the gating system or of its structural node is with regards to gas entrapment in the cast volume, more advantageous than the change in setting of technological parameters of the pressing system
Summary
High pressure die casting (HPDC) allows production of thin-walled casts with high geometrical precision, with positive mechanical properties and with low price. Defects such as porosity, which is primarily caused by air entrapment by melt during the filling phase, influences the cast quality [1,2]. Decreased quality caused by air entrapment in the cast volume manifests itself mainly by decline in mechanical properties and machinability. It has been proved that increased values of holding pressure positively influence distribution, size and volume of pores as well as cast tightness
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