The Hi-StA-Part project aimed to demonstrate the viability to produce aerospace grade aluminium parts using Direct Manufacture (DM) – specifically the process of Selective Laser Melting (SLM). The project demonstrated that components and parts can be manufactured with a significant weight reduction, to the required mechanical properties for aerospace applications.
The strategy of the project was to investigate the SLM processing of existing 7xxx (7075) series alloy powder and also using AlSc (Scalmalloy) material, which has been developed outside of the project, for processing by SLM. The 7075 Al alloy material was used to build mechanical test specimens using a state of the art 1kW SLM system (by partner TWI). As part of this activity, we investigated ‘part optimisation’; whereby part weight and materials usage can be minimised to show the true benefit of manufacturing by SLM. EADS Apworks used their own procedures and SLM systems to produce tensile, fatigue and corrosion specimens using AlSc powder material.
Throughout the project, energy and raw material usage were monitored, allowing a true and accurate comparison of the SLM process against existing manufacturing techniques to be undertaken as part of the project.
By successfully achieving the aims of this project – we demonstrated the potential for DM to manufacture Al alloy components to TRL 6. This will significantly help to maintain and improve the competitiveness of the European aerospace sector.
The main purpose of the Hi-StA-Part project was to investigate and develop the capabilities of the Selective Laser Melting (SLM) process with regards to the use of high strength aluminium alloys. It was also supported by the manufacturing of the demonstrator components chosen for this project with significant weight reduction, to the required mechanical properties for aerospace applications. Two demonstrator components were chosen for this project. One of them was the locking hub used in the aeroplane door opening mechanism and second was corner fitting component for aeroplane. There are several quantities of them installed on a plane depending on the different size and capacity.
In this project aluminium alloys such as Al 7xxx (7075) and AlSc (Scalmalloy) were the materials under investigation. As part of this investigation it was observed that use of aluminium alloy AL 7075 with the SLM process had limitations as crack sensitivity, high reflectivity and thermal conductivity. This led the project to select a new alloy, Scalmalloy, which is an aluminium-scandium based alloy. This alloy was selected due to its high strength capabilities and weldability. The mechanical and corrosion testing that was carried out showed the Scalmalloy material to be a suitable material of choice for the aerospace applications chosen.
The weight reduction of the components was achieved by means of topology optimisation software which runs the finite element analysis (FEA) simulation to get efficient material distribution for a given component and check it against its loading conditions. This redesign study usually increases level of complexity in terms of its shape. Traditional manufacturing technologies were not able to handle the level of complexity of this type of geometry/shape. However, this is an advantage for selective laser melting (SLM) process. The new designs were manufacturing by a research group which part of a big airframe assembly company in Germany and it was showed that they were made with 10-12 % reduced weight as compared to traditional design and manufacturing processes.
Life cycle analysis and sustainability study conducted in this project showed that selective laser melting (SLM) is more environment friendly, economical and sustainable process as compared to the conventional manufacturing processes used for manufacturing of the demonstrators components considered in this project. Overall this project demonstrated the use and implementation of innovative material (Scalmalloy), innovative design approach suitable for additive manufacturing (AM) and actual manufacturing of components by selective laser melting (SLM) to capture the benefits such as improved buy-to-fly ratio due to weigh reduction, reduced lead time, reduced wastage of material, cost-savings compared to conventional manufacturing process.