Abstract

Cutting preforms in complex 3D geometries  is one of the challeges of carbon fiber manufacturing for both prepreg and dry fibre parts. Even after cutting layer by layer, a subsequent process is still necessary  due to possitioning tolerances and the need of trimming of the edges. Nowadays, this process is carried out by hand. These manual cuts are performed on cutting mats and employ specific tooling to keep the preform in a fixed position and shape. Moreover, often it is necessary to move the preform into several cutting positions leading to poor ergonomics, specially for very thick preforms.

The process presented here attempts to solve this problem by introducing an automatic cut without any cutting mat nor complex and expensive fixing jig. The greatest difficulty of this approach lies on the flexibility of the preforms as they are not rigid enough to maintain their shape and position during the cut.

The solution combines a computer vision system  withan ultrasound cutting system embedded on a robotic arm. This may lead to improvements in productivity as well as in quality (Regarding cut tolerances and finish) as well as increased repeatability compared to manual processes, enabling the deveolpment of net preform cutting technologies. Templates are not required and tooling is simpler, so recurring costs plummet as well as set up times. This is specially useful for prototyping and short production series as cutting lines may be easily modified without making new templates since  the system is able to identify the new cutting path.