Rapid prototyping of aircraft canopy based on the incremental forming process

Abstract

Today, the incremental forming process is widely used as a rapid prototyping method. One of the strategic polymer parts in the aviation industry is the canopy of various aircrafts. Polycarbonate sheets with suitable mechanical, thermal, chemical, and optical properties are used in the manufacturing of the latest integral canopies. Conventional processes are not cost-effective for low-volume production of polymer products, particularly for spare parts. In this paper, rapid prototyping of a geometry similar to integral canopies is investigated using the incremental forming process of transparent polycarbonate sheets. To this aim, the apparent transparency and the geometric accuracy of the final parts were considered as the main concerns. In single-point incremental forming experiments, the effect of tool rotational velocity on apparent transparency and the effect of toolpath strategy on geometric accuracy of the samples were investigated. Three toolpath strategies including raster, spiral from outside, and spiral from inside were applied. According to the FE results, applied toolpath strategies did not noticeably affect the thickness distribution for the critical section. Post-heating treatment was also used to release process-induced residual stresses and reduce the spring back. The use of a non-rotating tool as well as a mechanical–chemical surface polishing improved the final finishing and transparency of samples. In addition, by the employment of the raster strategy, higher geometric accuracy was achieved compared with the other two strategies. The forming of samples with appropriate apparent transparency and geometric accuracy promises to apply the rapid prototyping of aircrafts canopy using the incremental forming processes.