Summary of public surveys and questionnaire answers
WP1 of StaCast Project is aimed at individuating by means of properly elaborated questionnaires (distributed using the mailing lists of each of the Partners) and of dedicated surveys (elaborated by some of the University Partners) the specific standardization needs for what concerns Al alloys castings.
This activity is the direct consequence of the StaCast Project motivation, which is based on four key-issues.
- The vast potential of Aluminium Alloys EU Foundry Industry strongly needs a coordinated set of Support Actions, in which a central role MUST be played by the elaboration of new and advanced Standards, particularly in the fields of Defects classification and Mechanical Design, which are mutually inter-related.
- The use of a new EU Standard for the Classification of Casting Defects, which will help EU Aluminium alloys foundries at promptly performing corrective actions to reduce/eliminate defects, is becoming strategic. Such Standard will be also a useful “communication tool” among all the actors of the design and manufacturing chain.
- The development of a new Standard on mechanical properties is strongly needed too, in order to correctly evaluate the effective mechanical potential of Al foundry alloys.
- The design and manufacturing of Al alloys cast components NEED the availability of dedicated rules and guidelines, in order to correctly make use of the two new standards deriving from issues 2) and 3).
The four issues above need, first of all, to be confirmed by a dedicated survey to be carried out on an EU basis. This is the background which led to the set up of the Questionnaire, and to the answers elaboration which are described in the present Deliverable.
Database on Defects
Defects are intrinsically generated by casting processes, due to several reasons. The final properties and in-service behaviour of castings are always related to microstructural features and to defects: both microstructure and defects are the results of process stages, alloys properties and dies & tools design. As an example, it should be considered that in HPDC filling stage extreme conditions are established: complexity of components leads to complex dies, and the high production rates required (up to 120 shots/h) lead to very high filling velocities for the molten alloy (up to 40 m/s) with strong generation of turbulence in the flow. Solidification takes place in few seconds, and the die is first in contact with a molten alloy at more than 700°C and, after 30-40 seconds, with a
sprayed lubricant at room temperature. For these reasons HPDC (as well as other Aluminium alloys casting processes, such as permanent mold casting process) can be considered a “defect generating process”. Not only an average 5-10% scrap is typically produced, but the type, size and severity of defects are varying.
From these considerations, it seems that the potential of high-pressure die-casting and permanent mold casting processes will be completely exploited only when the quality level will be perfectly optimised. In this regard, the analysis of defects allows the foundry to monitor the products quality respect to a quality standard. Further, the analysis of defects provide to the foundry useful correlations between defects type/distribution and their origin, so that it could be possible to define process modification for improving the quality.
One of the current targets of the StaCast project is the compilation and dissemination of common tools to allow foundries to define a proper, comparable, quality standard. The first tool to be proposed is a common basis of language, i.e. a terminology and classification of defects in order to help die-casting foundries to face with increased confidence and ability the defect-related issues, to assure quality and reliability of their products.