Tolerance Stack Up Challenges in Multi Hole Drilling Systems: A Comprehensive Review

Multi-hole drilling systems are extensively used in high-volume manufacturing sectors where strict positional and dimensional tolerances are required. Despite productivity benefits, these systems are highly susceptible to tolerance stack-up arising from machine tool inaccuracies, spindle synchronization errors, tooling wear, fixture compliance, and process-induced effects. This paper presents a concise and structured review of tolerance stack-up challenges in multi-hole drilling systems based on more than twenty-five peer-reviewed studies, standards, and textbooks. Key error sources, modeling approaches, experimental findings, and mitigation strategies are critically analyzed, and major research gaps are identified to guide future development of precision-oriented and intelligent multi-hole drilling systems.