ABSTRACT
Vehicles lightening is a common goal to all car manufacturers, with the aim to improve fuel economy and reduce CO2 emissions. It is not always easy, however, to reconcile the use of light alloys and conventional forming or casting technologies with the need to manufacture structural or engine components, with thin walls, complex shapes and adequate mechanical properties.

High Pressure Die Casting (HPDC) of Al alloys, which could be a viable technical and economical way to achieve the expected goals, is generally affected by the difficulty to obtain castings with the required soundness (and thus heat treatable) and, in addition, by the impossibility to achieve hollow sections or to produce parts with undercuts.

Ceramic cores and semi-solid forming technologies are two possible tools that could be used to overcome these problems.

The present paper describes the development of ceramic cores to be used in a prototype single-cylinder engine block, produced in both conventional HPDC and semi-solid casting, that allowed to achieve a closed-deck type geometry of the cooling water-jacket, not generally feasible with this family of casting processes.

In both cases the ceramic cores were able to withstand the mechanical stresses during the die filling (without breakage or changes in shape) and the packing pressure without any significant dimensional change. The castings were then processed with high pressure water jet to remove the cores and finally sectioned to verify the performance of de-coring process.

The suitability of ceramic cores for use in high pressure die casting processes, without any limit to process parameters, and the possibility to remove them with pressurized water have thus been confirmed.

Keywords: HPDC, ceramic core, structural component, hollow section