Iranian Journal of Manufacturing Engineering

Iranian Journal of Manufacturing Engineering

Experimental and statistical study of uncut fibers in the drilling of GLARE and CARALL Fiber-Metal Laminates

Document Type : Original Article

Authors
Ramin Beyranvand 1
Mehdi Ansari 1
Alborz Mohebi 2
Mohammad Kashfi 3
1 Department of Manufacturing, Faculty of Mechanical Engineering, Arak University of Technology, Arak, Iran
2 Department of Mechanical Engineering, Faculty of Engineering, Bu-Ali Sina University, Hamedan, Iran
3 Department of Mechanical Engineering, Faculty of Engineering, Ayatollah Boroujerdi University, Boroujerd, Iran
10.22034/ijme.2026.555124.2145
Abstract
Fiber–metal laminates (FMLs) of the GLARE and CARALL families are widely utilized in advanced industries such as automotive and aerospace due to their high strength-to-weight ratio and favorable mechanical performance. However, drilling these hybrid laminates remains a fundamental challenge in ensuring hole-surface quality and structural integrity. In this study, a multifactorial analysis of uncut fibers and hole-surface quality in GLARE and CARALL laminates was conducted under controlled drilling conditions. For this purpose, a full factorial experimental design was employed with three spindle speeds (1000, 1600, and 2500 rpm), three feed rates (8, 16, and 25 mm/min), and three tool diameters (3, 5, and 7 mm). The results indicated that CARALL samples exhibited significantly lower amounts of uncut fibers and superior hole-surface quality compared to GLARE, which is attributed to the higher stiffness, stronger fiber–matrix interfacial bonding, and improved thermal stability of carbon fibers. GLARE showed greater sensitivity to changes in feed rate and tool diameter, where increasing the feed rate intensified the formation of uncut fibers and increased surface roughness. Force–time analysis revealed that increasing spindle speed reduced thrust force and improved hole-surface quality in both systems, although the effect was more pronounced in GLARE. The influence of tool diameter demonstrated a nonlinear trend: smaller diameters reduced the presence of uncut fibers, whereas larger diameters led to increased thrust force and interlaminar damage. Overall, the findings confirm the superior resistance of CARALL to uncut-fiber formation and its ability to maintain higher hole quality.
Keywords
Fiber&ndash
Metal Laminates, Composite Drilling, Uncut Fibers, Hole Surface Quality, Machining Parameters
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