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Solutions to Detachment Defects for Projection Welding of Screws on Plates with Capacitor Discharge Spot Welds
Jul 25,2026
Projection welding between plates and screws is an efficient connection process widely adopted in manufacturing industries. Capacitor discharge spot welders are mainstream equipment for this process, featuring instantaneous energy release, narrow heat-affected zones and high energy efficiency. Its core working principle: capacitors store energy in advance and release high low-voltage current within a short period; heat generated by contact resistance melts screw projections to form nuggets and achieve firm bonding.
I Root Causes of Detachment
1.Unbalanced energy input: Improper charging voltage & discharge duration lead to abnormal nugget formation. Aging capacitors or loose oxidized charging circuits cause unstable energy output and batch detachment defects.
2.Poor electrode condition: Mismatched electrode material, wear, oxidation or misalignment create uneven current & pressure transfer and insufficient melting of projections.
3.Unsuitable welding force: Insufficient or excessive electrode pressure, insufficient fixture rigidity result in poor contact and weak nuggets, aggravating detachment.
4.Inadequate workpiece pre-treatment: Oil, rust on plates/screws, deformed screw projections or assembly deviation prevent effective metallurgical bonding.
5.Lack of fixture & equipment maintenance: Absence of dedicated positioning jigs causes screw offset; inadequate cooling & calibration, degraded capacitors reduce current/pressure precision.
6.Non-standard operation & process: Random parameter adjustment, misaligned workpieces, discharging without full compaction, unreasonable welding sequence and improper post-weld treatment all trigger detachment.
II Targeted Solutions
1.Optimize welding parameters: Precisely adjust charging voltage, discharge time and electrode pressure according to plate & screw material/specifications; lock parameters after passing trial welding verification.
2.Improve workpiece quality: Use qualified screws; clean surface contaminants before welding and weld immediately to avoid secondary oxidation; flatten plates and eliminate assembly misalignment.
3.Standard electrode maintenance: Adopt high-temperature wear-resistant matched electrodes; clean, grind or replace worn electrodes daily; calibrate coaxial alignment regularly and guarantee unobstructed cooling channels.
4.Upgrade fixture positioning: Apply special jigs with locating pins and enhance fixture rigidity to avoid screw offset and local stress concentration.
5.Strengthen equipment maintenance: Inspect capacitor capacity regularly and replace aged ones; perform daily equipment inspection; calibrate current & pressure weekly and troubleshoot circuit faults timely.
6.Standardize operating procedures: Train operators to align workpieces accurately and compact fully before discharging; cool naturally post-weld and remove spatter; conduct batch inspection to spot abnormalities.
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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