CORDIS - EU research results

Increase of the productivity and efficiency of injection processes through the use of metallic foam concepts in the production of moulds (FOINMOULDS)

Final Report Summary - FOINMOULDS (Increase of the productivity and efficiency of injection processes through the use of metallic foam concepts in the production of moulds)

High pressure die casting (HPDC), injection moulding and blow moulding are dominating near-net-shape technologies for the production of light metal and plastic components. Today, more than 2 000 EC small and medium-sized enterprises (SMEs) are involved only in the mould making industry, with a yearly turnover of more than EUR 6 billion. Due to exhausting competition of 'low cost' countries outside the European community (mainly from Far East), dramatic changes are taking place in these industrial sectors to get more competitive products while reducing costs. This way, the European SMEs of these sectors find the need to improve the quality and performance of their metallic and plastic products, to optimise their production processes and to accept new challenges of new products developments to increase their market share.

The main objective of the project FOINMOULDS was to develop new aluminium HPDC, polymer injection and blow moulding mould concepts in which metallic foams were to be integrated to attain an increased efficiency in heat management control of the three processes. Metallic foams integration could also derive in moulds weight reduction, which, together with improved and better-controlled heat dissipation, would lead to:
- improved mould temperature control;
- controlled local solidification;
- reduced mould distortions;
- avoidance of component distortions;
- improved feeding;
- reduced mould wear and, therefore, improved surface quality of products, therefore, better quality products and reduced processing times would be obtained.

Different mechanical and thermal simulations were carried out to investigate the response of the overall system when the selected foams are integrated into the demonstrator moulds, identifying the main parameters controlling the mould behaviour and the processes. Conceptual mould designs for each of the demonstrators were established: A new blow moulding demonstrator mould was to be built in which close cell aluminium foams were to be integrated as part of the structure of the mould and open cell foams were to be inserted in the modified cooling channels. With respect to the injection and HPDC demonstrators, it was decided to integrate the open cell foams into certain of the cooling channels of the existing moulds. The possibility of enlarging the cooling channels was also studied.

Next, the research and technological development (RTD) performers carried out a broad mechanical (compression and flexural tests), thermal (thermal conductivity, heat transfer behaviour) and corrosion characterisation of the close cell and open cell foams acquired in previous tasks and of the foams produced by the partners.

In the following steps, the integration, assembly and finishing technologies for the application of the cellular metals in the moulds' cooling channels or structures were investigated. Different cutting techniques for the foams were tested, such as water jet cutting, sawing, milling and spark eroding.

Several approaches to improve the cooling were studied and, finally, a concept where the cooling system was adapted to the cavity shape was manufactured and, afterwards, open cell aluminium foams were inserted in the cooling channels.

As a complement to the testing in service conditions of the built demonstrators, and in order to gain a better insight of the thermal behaviour of the system, different aluminium and hot-working steel test blocks with foams inserts of different types were constructed.

The results showed that the inclusion of foams into the cooling channels improved the thermal behaviour of the moulds. However, the reaction of the overall system depends upon all components of the system (heating station, pipes, mould, foam) so that a very simple generalisation of this positive result to other systems is not possible. In the next phase of the project, the industrial tests were conducted based on the demonstrator moulds built in previous work packages (WPs).

Based upon the results of the experimental tests and the experiences regarding the application of the cellular materials and the mould manufacturing, a technical and economical evaluation of the application of foams in moulds was carried out. In summary, this evaluation led to the conclusion that the utilisation of the metallic foams can provide significant benefits to the considered industrial processes.

In general, the activities performed throughout the project have demonstrated that the application of the metallic foams has a positive influence on the response of the moulds which leads to improvements on the three manufacturing processes considered, both in technical and economical aspects.

A mould concept with integrated foams with improved thermal dissipation and mechanical behaviour over conventional moulds was developed. This result stemmed on the integration of metallic foams in conventionally manufactured moulds. The foams provided better heat dissipation rates. The present result is of general application for the three technologies considered in the project, that is, blow moulding, polymer injection and aluminium HP die casting.

Also, a mould concept with integrated foams based on rapid tooling techniques was developed which allowed reducing the parts' manufacturing cycle in 25%. This result relies on the combined solution of a mould manufactured by rapid tooling techniques and integrated metallic foams for improving the thermal regulation and the mechanical response of the system. The investment casting process allows the designer integrating directly the metallic foams in the mould parts which reduces later manufacturing steps for integrating such foams. Additional aspects that must also be considered are the mould manufacturing costs and time and the reduced weight of the new mould. The mould could be delivered in half time with a 35% estimated reduction of the manufacturing costs.

In addition, the relevant physical, mechanical and thermal properties of the foams were determined for their application in thermal management and structural applications in moulds. A complete database of foams' properties that allowed tackling the subsequent moulds' design and manufacturing phases and selecting the most suitable foams for each of the demonstrator moulds was obtained. This database could be used for the application of the cellular in other moulds and processes.

Regarding the foam technology, the application of new alloys was investigated for the production of foams, new foam's geometries at different scales and pore-sizes were also obtained extending the range of available cellular materials in general.

The feasibility of using conventional cutting and assembly techniques for the integration of the foams into the moulds was proved and the most suitable techniques for the purpose of each foam application was identified among water jet cutting, sawing, milling and spark eroding and adhesive bonding, pressing and soldering.

Another relevant fact that has been confirmed is that the behaviour of the moulds during the considered injection processes is complex and, as ascertained by the tasks performed within the project, it becomes even more complicated when the foams are introduced. The work carried out has provided additional understanding of the influence of metallic foams on the mould behaviour. Thus, the experience gained by the partners offers the possibility for consultant services for injection moulders and foundries which may represent an extension of the portfolio beyond just foam production or application.