Delamination Factor Analysis in Cryogenically Drilled Holes in Fiberglass Reinforced Structures

Abstract

Composite structures, such as glass fiber reinforced polyether-ether-ketone (PEEK) and polyamide (PA66), usually undergo drilling operations for subsequent assembly. A typical problem with these composites is damage around the drilled surface due to a possible non-homogeneous cutting of the fibers. In this context, the delamination is evaluated after a cryogenic drilling. Thus, the objective of this paper is to determine the feasibility of cryogenic drilling considering surface damage after cryogenic machining, at hole the entry and exit. Experimental test were carried out in a machining center at a temperature close to -130 °C using liquid nitrogen, LN2, as cooling environment. The diameter of the drill is 6 mm and the drill tip is polycrystalline diamond (PCD). The plate material is PEEK-GF30 and PA66-GF30. The delamination factor was obtained using a three-dimensional measurement device with an optical sensor and a focus-variation device. The results obtained are favorable regarding the potential use of cryogenic machining.