Mechanistic and experimental correlation of pre-burnishing and drilling cycle effects on burr formation in AISI 316 L

This study investigates the effects of pre-burnishing and drilling cycle strategies on entry-burr formation and surface integrity during dry blind-hole drilling of AISI 316L stainless steel. Flat ball-burnishing was applied before drilling using 0, 2, and 3 passes, followed by constant-increment peck (CIP), constant-increment break-chip (CIBC), or variable-increment peck (VIP) cycles. Thrust force, burr geometry, surface roughness, and microhardness were evaluated. Pre-burnishing reduced thrust force by approximately 20% and entry-burr height by nearly 80% after two passes, while improving surface roughness by approximately 70% and increasing near-surface microhardness by up to 100%. Minimal burr formation despite non-minimum thrust levels indicated that burr suppression depends on restricting localized plastic flow rather than force reduction alone. Two-pass burnishing combined with CIBC provided stable cutting and low burr heights. A mechanistic contact-based scaling model showed good agreement with experimental trends, demonstrating pre-burnishing as an effective strategy for improving AISI 316L drilling performance.