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The ‘full sleeve’ application in the horizontal cold-chamber machine for pressure die casting of aluminium alloys

Keywords: Pressure die casting , Aluminium alloys , Pressure chamber

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Abstract:

The ‘full sleeve’ construction has been designed and accomplished in the horizontal cold-chamber pressure die casting machine. Main part of this solution is a counter plunger placed in a movable die half which allows for full filling of the shot sleeve and precisely fixes the metal quantity needed for casting. The purpose of this new construction solution is mainly the reduction of the casting porosity caused by air entrapment and the improvement of both castability and accuracy of the die cavity reproduction. For such a redesigned machine there have been performed examinations consisting in pressure casting of AlSi9Cu alloy (EN AC-46000) at varying plunger velocity in the second stage of injection and varying intensification pressure. The alloy castability (the die filling ability) has been measured for each parameter setting. For the purpose of comparison, similar measurements have been performed also for the conventional system without a counter plunger. The castability examination has been done by means of a specially designed die with an impression of a trial casting of variable wall thickness. The experiments have been held according to the assumed factor design 22, what allowed for determining the mathematical models describing the influence of die filling parameters on the castability and the die cavity reproduction level. Both alternatives of the experiment confirmed the positive influence of plunger velocity and intensification pressure increase on the improvement of castability, the measure of the latter being the filled length of the impression. Applying of the new ‘full sleeve’ solution has improved castability for each experiment by about 20% as compared with conventional alternative. Castability in the ‘full sleeve’ system has been increased even for low values of plunger velocity and intensification pressure. For both alternative systems the influence of plunger velocity has been found, as an average, by four times greater than the influence of intensification pressure. The possibility of applying lower pressure values has been noticed for the shot sleeve construction with the counter plunger. This can influence favourably both the die and the machine durability. The obtained results have been explained and it has been pointed out that the ‘full sleeve’ construction can be widely adopted in pressure die casting of metal alloys.

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