Abstract
Drilling is the most frequently used machining method on composite material for the need of structure joint, which often causes delamination at the exit of composite drilling. Delamination is one of the major problems of composite drilling, will reduce the mechanical strength of composite material. For increasing usage of composite material in aerospace and automobile, such as Boeing787 or Tesla electrical vehicle, delamination is not only mechanical problem but safety concern. Therefore, reducing delamination is an important issue for composite machining. There are several methods for flat composite material to reduce delamination during drilling but few for curved surface. This study proposes an idea using electromagnet and colloid mixed with iron powder to produce magnetic back-up force and reduce delamination at exit of composite drilling. The experimental parameters include feed rate, current, and iron powder volume concentration. The result shows that delamination area grows with increasing feed rate and reduced electrical current. It also finds that there is an optimal value for iron powder volume concentration of about 24% in this method.