A comparative evaluation of polycrystalline diamond drills in drilling high-strength T800S/250F CFRP

Abstract Applications of high-strength CFRP are usually focused on manufacturing the key load-bearing structural components of large commercial aircrafts in modern aerospace industry. Machining of the high-strength CFRP is very challenging and difficult due to its extremely superior mechanical and physical properties. Polycrystalline diamond (PCD) tools are commonly identified as an attractive tool solution for CFRP machining. However, investigations on the cutting performance of PCD drills in high-strength CFRP drilling are limited and not widely performed. In this paper, two types of PCD drills (PCD standard twist drill and PCD special-geometric dagger drill) were adopted and evaluated when drilling one type of high-strength CFRP (T800S/250F). The experimental results confirmed that the PCD dagger drill seemed to provide a better tool-work configuration than the PCD twist drill for high-strength T800S/250F drilling in terms of better hole quality, lower tool wear and longer tool life. SEM and EDS analyses suggested that abrasive wear and adhesive wear were the dominant wear modes governing the PCD wear progression. Serious catastrophic failures like coating peeling and edge chipping took place for the PCD drills when cutting of T800S/250F CFRP.