An Investigation of the Deformation Patterns Due to the High-Speed Micro-Laser Drilling Process for Ti-6Al-4V Used in Aerospace Applications

Abstract

Hybrid Laminar Flow Control (HLFC) is used in the aviation industry to reduce fuel consumption of civil jet aircrafts. Small holes are required at the leading edges of the aircraft wings and tail planes to reduce friction caused by boundary layer suction. Much research has been made in the application of drilling small holes to Ti-6Al-4V alloys. The most important of these investigations is that the thermal distortion cannot be controlled during the application of a large number of holes in huge areas and thus, it causes deformation as a result of thermal deterioration. When micro drilling is applied, some problems arise due to close proximity of drilled holes. The aim of this investigation is to evaluate the deformation due to the micro laser drilling process and develop an efficient set of certain laser parameters to minimize it. 50 W power pulsed Ytterbium fiber laser having a galvo scanner have been used during the process. The effects of increased waiting time, use of weight on both sides of the specimens and nitrogen cooling upon the deformation of the drilled samples have been investigated. Before and after the drilling process the samples have been scanned by a 6-axis arm CMM having an integrated 3D laser scanner. The deformation patterns have been obtained with the use of PC-DMIS software. As a result, as the waiting time is increased, less deformation has been observed in the samples. In addition, addition of nitrogen gas to the process has positively influenced the deformation minimization efforts.