Experimental Investigation on drilling behavior of carbon-Kevlar monolithic and interyarn hybrid composite

Carbon-Kevlar interyarn hybrid composites are sufficiently stiff and tough, which makes them useful in various sectors. Despite these potentials, their drilling behavior has not yet been explored. Drilling composite materials generates defects due to the distinct properties of the fiber and matrix. This study explores the drilling behavior of carbon-Kevlar monolithic and interyarn hybrid thermoplastic composite by changing tool geometries, feed rates, and spindle speeds. The chip morphology, drilling temperature, thrust force, delamination factor, and hole wall surface were analyzed. Three types of composite laminates (monolithic carbon, monolithic Kevlar, and carbon-Kevlar interyarn hybrid composites) were fabricated. Holes were made by two different geometries (conventional twist drill and brad spur drill) at varying feed rates (15, 30, and 45 mm/min) and spindle speeds (1000, 2000, and 3000 rpm). Compared with the conventional twist drill, the brad spur drill produced a 32.40 % reduction in maximum drilling temperature, 29.73 % less thrust force, and 13.57 % less delamination factor for the carbon-Kevlar hybrid composite. Based on the microstructural analysis, the brad spur drill produces a better surface with lesser fiber fracture, delamination, cavity, and matrix smearing than the conventional twist drill for all three composites.