Orbital Drilling of Sandwich Constructions for Space Applications

This paper deals with orbital drilling of sandwich constructions for space applications. Sandwich constructions for space applications are typically made up of thin layers of carbon fiber composite skins separated by an aluminum or carbon honeycomb core. Drilling holes in such structures is required for assembly purposes. A common and significant problem occurs when drilling such structures with conventional methods, namely delamination on the exit side of the composite layers. In this study orbital drilling is investigated as a means of eliminating delaminations and other frequently encountered problems with conventional drilling of laminated composite structures. Holes of different sizes were drilled in sandwich panels using orbital drilling. Both automatic (CNC) and semi-automatic (portable) orbital drilling were investigated. Damage in the vicinity of the holes was assessed by means of microscopic evaluation. It was concluded that orbital drilling effectively eliminated delaminations and other types of damage in the composite skins. In addition other significant advantages of orbital drilling are highlighted in this paper.