<p>Hole burnishing serves as a highly efficient and economical technique for improving the fatigue performance of aluminum alloy load-bearing holes. However, the effectiveness of burnishing is limited by the presence of the critical burnishing depth (BD). This study employs aluminum alloy 7050 to explore approaches for increasing the critical BD by altering the shape of the contact geometry between the tool’s roller and the workpiece. The chamfer radius at the bottom of the roller is set to 1.25 mm, 2.5 mm, and 5 mm. The most significant finding of this study is that optimizing the roller chamfer size substantially improves surface quality. To elucidate the underlying mechanism, a novel kinematic and dynamic analysis model is proposed, introducing the concepts of material deformation duration (MDD) and the rate of normal-direction deformation (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\dot{\text{N}\text{D}\text{D}}\)</EquationSource> </InlineEquation>). Theoretical and experimental analyses demonstrate that increasing the chamfer radius extends the MDD while reducing the <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\dot{\text{N}\text{D}\text{D}}\)</EquationSource> </InlineEquation>. This kinematic alteration effectively mitigates the friction between the roller and the workpiece, suppressing the transition from rolling to sliding friction. Consequently, a stable rolling contact is maintained, preventing material tearing and fragmentation caused by sliding contact, thereby effectively inhibiting surface defects. Furthermore, the influence of the chamfer size on micro-hardness, residual stress, and hole wall geometry is investigated. The results indicate that the chamfer size yields no significant improvement in micro-hardness and residual stress. Additionally, while increasing the chamfer size brings the final hole diameter closer to the target value, it deteriorates the axial consistency of the hole wall, presenting a disadvantage for precision machining. Given that fatigue life is the ultimate metric for burnishing efficacy, the significant improvement in surface quality highlights the importance of chamfer optimization. The results indicate that the tool with a 2.5 mm radius resulted in better surface roughness after burnishing, and the fatigue life was maximized with 0.1 mm BD and 2.5 mm radius, representing an increase of 119.81% compared to the unburnished hole.</p>

Interface axial evolution process and surface integrity improvement mechanism of aluminum hole burnishing

期刊论文
发表日期：

2026年3月21日

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Xiaoxuan Chen,
Pingfa Feng,
Jianfu Zhang,
Feng Feng,
Xiangyu Zhang

摘要

Hole burnishing serves as a highly efficient and economical technique for improving the fatigue performance of aluminum alloy load-bearing holes. However, the effectiveness of burnishing is limited by the presence of the critical burnishing depth (BD). This study employs aluminum alloy 7050 to explore approaches for increasing the critical BD by altering the shape of the contact geometry between the tool’s roller and the workpiece. The chamfer radius at the bottom of the roller is set to 1.25 mm, 2.5 mm, and 5 mm. The most significant finding of this study is that optimizing the roller chamfer size substantially improves surface quality. To elucidate the underlying mechanism, a novel kinematic and dynamic analysis model is proposed, introducing the concepts of material deformation duration (MDD) and the rate of normal-direction deformation ( \(\dot{\text{N}\text{D}\text{D}}\) ). Theoretical and experimental analyses demonstrate that increasing the chamfer radius extends the MDD while reducing the \(\dot{\text{N}\text{D}\text{D}}\) . This kinematic alteration effectively mitigates the friction between the roller and the workpiece, suppressing the transition from rolling to sliding friction. Consequently, a stable rolling contact is maintained, preventing material tearing and fragmentation caused by sliding contact, thereby effectively inhibiting surface defects. Furthermore, the influence of the chamfer size on micro-hardness, residual stress, and hole wall geometry is investigated. The results indicate that the chamfer size yields no significant improvement in micro-hardness and residual stress. Additionally, while increasing the chamfer size brings the final hole diameter closer to the target value, it deteriorates the axial consistency of the hole wall, presenting a disadvantage for precision machining. Given that fatigue life is the ultimate metric for burnishing efficacy, the significant improvement in surface quality highlights the importance of chamfer optimization. The results indicate that the tool with a 2.5 mm radius resulted in better surface roughness after burnishing, and the fatigue life was maximized with 0.1 mm BD and 2.5 mm radius, representing an increase of 119.81% compared to the unburnished hole.