ADDITIVE MANUFACTURING OF PARTS FOR A SOUTH AFRICAN PROTOTYPE AIRCRAFT

Aerosud is in the process of developing a new tandem aircraft which will be produced locally. This aircraft will be certified and used for military purposes. Even though additive manufacturing is still relatively new to the aviation industry, it was decided to use this process to create parts not only for the Environmental Control System, but also for a number of other applications in the aircraft. Parts included structural and non-structural parts and needed to conform to fire smoke and toxicity standards for interior aircraft parts. Additive manufacturing is ideal because it gives the designer the opportunity to design one complex part instead of a combination of simple parts. In the end this is more compact, it saves weight, reduces design time and costs which are all critical for aircraft design. Fused deposition modeling (FDM) was the process of choice after it was compared to selective laser sintering (SLS). Due to the setup of the project, parts were manufactured as soon as the design was complete. With SLS, the only way to manufacture parts cost-effectively is to do so in large batches. FDM on the other hand allows parts to be manufactured individually, at no extra cost. Ultem 9085 is a material which is already aviation certified and was the selected material for the project. In total there were 88 parts manufactured, of which 61 are currently on the aircraft. Some parts were scrapped mostly due to design changes and not due to defect. Some of the problems encountered during this process were: Support material that had to be removed in hard to reach places; the implications of the machine stopping in the middle of a build; vibrations on tall, narrow parts and holes in the parts creating unnecessary support material. Other challenges were how to produce accurate cylinders, countersink holes and to rivet FDM parts to other structures. To minimize these problems and challenges a new “design mind set” had to be developed. To further develop this mind set, a better understanding of the process and mechanical properties are required. Manufacture orientation and mechanical property tests will be one way to gain a better understanding.