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Operation Tips to Prevent Interlayer Incomplete Fusion in Multi-Light Sheet Seam Welding via Medium Frequency Seam Welders
Jul 13,2026
The most common hidden defect in multi-layer thin sheet rolling welding is interlayer incomplete fusion and layered pseudo-welds. Such welds look intact and pass short-term leak testing, yet internal bonding fails. Under pressure, vibration and oil storage during service, they develop delamination, bulges and fluid leakage or detachment.
I Process Difficulties of Multi-Light Sheet Rolling Welding
1.Tiny gaps easily form between stacked sheets; trapped air blocks heat transfer.
2.Thin sheets hold minimal heat; heat input is hard to balance, leading to either incomplete fusion or burn-through.
3.Pressure only acts on outer surfaces, often fusing top sheets while middle layers remain separated.
4.Uneven plate contact and interlayer contaminants hinder metal fusion and create pseudo-joints.
II Typical Signs of Interlayer Incomplete Fusion
1.Weld surface free of pores, blackening or discontinuities; no fusion traces between layers.
2.Consistent pattern: outer layers bonded firmly, middle/bottom layers delaminated.
3.Unstable weld quality with intermittent local interlayer gaps.
4.Zero leakage in initial water test, chronic seepage after field operation.
III Root Causes of Interlayer Incomplete Fusion
1.Improper welding pressure: Low pressure cannot squeeze out air from interstices, leaving middle layers unfused; excessive pressure cancels contact resistance and results in full-length pseudo-welds.
2.Insufficient heat penetration: Fast speed and low current shorten heat dwell time; heat only reaches top sheets, leaving middle/bottom layers cold and unfused.
3.Poor roller precision: Worn, grooved, misaligned or non-parallel rollers create uneven force, unilateral compaction and long strip interlayer gaps.
4.Interlayer contaminants: Oil, dust and oxide films form isolating barriers; vaporization creates micro-pores and worsens loose pseudo-fusion.
5.Unstable cooling & heat input: Over-intense water cooling drains surface heat, leaving inner layers underheated; machine stalling and variable speed cause erratic local incomplete fusion.
IV Process Improvement Solutions
1.Calibrate roller precision
Adjust roller parallelism and coaxiality; grind away grooves, built-up metal and burrs; fix machine jitter/looseness to ensure uniform full-length compression and eliminate suspended sheet areas.
2.Prioritize pressure adjustment over current for multi-layer welding
Use stable moderate pressure to squeeze out all interlayer air without thinning or collapsing sheets, enabling gradual heat penetration through all layers for full fusion.
3.Reduce welding travel speed
Slow down and maintain constant speed, eliminate speed fluctuation and machine pause to extend heat residence and fully melt middle/bottom layers to avoid interlayer voids.
4.Match medium current range
Avoid over-high current burning or under-low cold fusion. Stabilize pressure and speed first then fine-tune current for gentle gradual heat penetration, preventing sealed outer layers with unfused inner sections and ensuring dense weld nuggets.
5.Moderate water cooling intensity
Cut cooling power slightly to reduce surface heat loss and retain sufficient heat in welding zones for multi-layer bonding; meanwhile keep cooling flow smooth and constant for consistent quality.
6.Standard pre-treatment & stacking alignment
Clean oil, rust and oxide from every contact surface of sheets pre-weld. Align and compress sheets neatly without warping or offset; use dedicated fixtures to unify stacking tightness for every batch.
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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