ULTRAGASSING

DEVELOPMENT OF A DEGASSING SYSTEM FOR ALUMINIUM CASTING PROCESSING BASED ON ULTRASOUND

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 Obiettivo del progetto (Objective)

'Light alloys play the main role in vehicles weight reduction and in the last years the amount of aluminium parts in new vehicles has been steadily increasing. Moreover, weight is even a more critical factor in newly developed electric and hybrid vehicles, as it highly affects their autonomy. The global green house savings from the use of aluminium in vehicles is expected to double by 2025.

The use of aluminium alloys is however limited by the quality and insufficient properties of the cast parts that suffer from gas porosity.

The presence of hydrogen in the molten metal is the mainly reason of gas porosity in high performance components, which is currently dealt with by melt degassing techniques that involve purging of gas mixtures (often containing chlorine and fluoride) through the melt. This technology is expensive, has limited efficiency and poses health hazard.

Previous research demonstrated that treating the liquid metal with ultrasound highly reduces the concentration of hydrogen, improving the quality or the cast parts and increasing the efficiency of some existing degassing techniques when combined with them. The known demonstration of the efficiency of ultrasound-aided degassing has been done on laboratory and pilot scale, and not in the mass production of cast components.

The Ultragassing Project intends to define a method to apply the ultrasound degassing treatment in light-alloys foundry (most of foundries are SMEs), providing the foundry with the environmentally friendly and safe means to improve the quality of cast parts.

During the Ultragassing Project the link between parameters of ultrasonic degassing, melt quality and casting parameters will be established, which will allow the development of versatile technology that can be finely tuned to the specific casting process. This new degassing technology based on ultrasound will be validated and compared in performance with the currently used ones.'

Introduzione (Teaser)

Aluminium alloys play a vital role in vehicle weight reduction in the transport sector. Novel technology to minimise the formation of porosities during the casting process will enhance the competitive position of the related foundries and restore lost jobs.

Descrizione progetto (Article)

EU factories that produce metal castings (foundries) face intense competition from foreign manufacturers. Low-cost labour and lax regulations make it cheaper and easier for them to do business. Nearly a quarter of jobs in the foundry sector have been lost within the last few years.

The small companies that dominate the sector lack the infrastructure and financial means to carry out the necessary research and development to push ahead of the competition. The EU-funded project 'Development of a degassing system for aluminium casting processing based on ultrasound' (http://www.ultragassing.eu/ (ULTRAGASSING)) tackled one of the most important challenges facing the foundries that work with alloys not containing iron (non-ferrous).

Casting is a common metal and alloy-forming technique where a liquid or molten material is poured into a mould to cool and solidify into the desired shape. However, the structural integrity of the finished part is often compromised by the formation of small voids or porosities in the materials. In particular, aluminium alloys are subject to porosities due to the presence of hydrogen gas bubbles in the molten metal.

Current degassing techniques are expensive, inefficient and harmful to human health. The novel ultrasonic degassing technique developed by the ULTRAGASSING project improves melt quality by removing hydrogen gas and oxides during casting. In addition, with no harmful gas emissions, it is a safe and environmentally friendly method that meets current and future potential environmental regulations.

The team has built two prototypes for aluminium degassing via ultrasonic vibration of the metal: one for high-pressure die casting, and the other for low-pressure die casting and gravity casting. This optimised and versatile scheme, applicable to both continuous and batch processes, produced similar or better mechanical properties and porosity indicators compared to currently available technologies. The process reduces production time, enhances product quality and completely eliminates the use of harmful materials. Benefits abound for small companies, consumers and the environment.