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Methods to Avoid Poor Interlayer Bonding in Multi-Layer Sheet Spot Welding with Medium Frequency Spot Welders
Jul 15,2026
Interlayer slag and pinholes are frequent defects during multi-layer sheet spot welding. Oxide residue and oil trapped between layers break metallurgical bonding, lowering joint strength and causing loosening or cracking.
I Root Causes of Poor Interlayer Bonding
1.Incomplete pre-weld cleaning: Oil, oxide films remain between stacked sheets; warped or misaligned plates create interlayer gaps preventing tight contact and full fusion.
2.Unbalanced heat penetration: Heat concentrates on outer sheets only, inner layers receive insufficient energy to form solid nuggets, resulting in internal cold joints.
3.Equipment & operational issues: Improper parameters, worn/misaligned electrodes cause uneven current & heat distribution; loose fixtures make sheets shift during welding.
4.Material mismatch failure: Welding dissimilar multi-layer sheets without tailored heat parameters leads to inadequate interlayer fusion.
II Solutions for Interlayer Fusion Defects
1.Complete pre-weld preparation: Remove oil & oxide from all contact surfaces, flatten warped sheets and eliminate assembly gaps for full contact.
2.Optimize welding parameters: Adjust heat input and pressure according to sheet count & material to ensure heat penetrates all inner layers for full interlayer fusion.
3.Standardize electrodes & fixtures: Select matched electrodes, grind & clean routinely; use dedicated positioning jigs to fix sheets without shifting.
4.Standardize workflow: Prohibit arbitrary parameter changes; perform trial welds before mass production and conduct regular quality inspection.
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Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
Add: 28 Shuiyun Road, Yuecheng, Jiangyin, Jiangsu Province, China. (Postal Code: 214404)
Mobile: +86 18915302352
Email: wushijie@jshaifei.com