The work deals with the influence of change in the filling conditions of the ceramic moulds with plaster binder on the presence of gaseous
porosity and the microstructure of the achieved test castings with graded wall thickness. Castings made of EN AC-44000 alloy, produced
either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the Vacumetal
technology), or by counter-gravity casting were compared. The results of examinations concerning the density of the produced castings
indicate that no significant change in porosity was found. The increased size of silicon crystals was found for the increased wall
thicknesses due to the slower cooling and solidification of castings.
The performed examinations concerning the process of filling the plaster ceramic moulds with aluminium alloys allowed to assess the
influence of various methods of introducing the metal into the mould cavity on the macro- and microstructure of the obtained experimental
castings. The comparison was performed for castings with graded wall thickness made either of EN AC-44000 alloy or of EN AC-46000
alloy, produced either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the
Vacumetal technology), or by counter-gravity casting. It was found that the silicon crystals grow in size with an increase in wall thickness
due to the slower cooling and solidification of castings.