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If carbon buildup on the die surface of a copper diffusion welding machine is not cleaned, what welding defects may it cause?
Nov 09,2026
When a copper diffusion welding machine welds copper flexible connections and copper busbars, carbon buildup and stuck material on the graphite die surface that are not cleaned in time may affect heat transfer and contact and lead to various welding defects.
I. Uneven heat transfer and temperature deviation
1. The carbon layer conducts heat differently from the graphite body, so the local die temperature deviates and the workpiece is heated unevenly.
2. Where the carbon is thicker it insulates, the interface temperature is insufficient, the copper layer diffuses incompletely and the bond is not sufficiently firm.
3. Uneven temperature distribution makes the bonding state differ from part to part on the same product.
II. Uneven pressure distribution and poor contact
1. Carbon and stuck material make the die surface uneven, the workpiece is locally suspended and pressure transmission is insufficient.
2. Local compaction is insufficient, gaps remain between copper foil and busbar layers, and the diffusion bond area is reduced.
3. Uneven force also tends to misalign the workpiece, causing dimensional deviation after welding.
III. Delamination, peeling and bulging defects
1. Gas and volatiles adsorbed by the carbon layer are released at high temperature and trapped between layers, forming bubbles and bulges.
2. Surface impurities separate the workpiece from the die, local diffusion is insufficient, and delamination and peeling appear after welding.
3. At carbon buildup the pressure and temperature are both insufficient, so these areas easily become a concentration zone of delamination defects.
IV. Product surface quality and appearance problems
1. Carbon, copper chips and other impurities are pressed into the workpiece surface under high temperature and pressure, forming indentations and pitting.
2. Stuck material may cause local adhesion and scoring on the workpiece, affecting appearance quality.
3. Surface impurities may also affect subsequent processes, increasing cleaning and rework costs.
V. Die and equipment wear
1. The carbon layer concentrates local stress, aggravating wear, depression and cracking of the die.
2. Uneven heat transfer makes the die repeatedly bear thermal cycling stress, shortening its life and increasing replacement frequency.
3. Impurities react and stick to the die at high temperature, making cleaning harder and compounding the losses.
Wuxi Haifei Intelligent Equipment Co., Ltd. official website: https://www.haifeiwelder.com/
Wuxi Haifei Intelligent Equipment Co., Ltd. has been dedicated to the research and production of diffusion welding machines for 17 years. The company has passed the ISO9001 quality management system certification, the national 3C certification and the CE certification. It is a national high-tech enterprise, a Specialized, Refined, Distinctive and Innovative enterprise of Jiangsu Province, a Specialized, Refined, Distinctive and Innovative enterprise of Wuxi City, and a Gazelle enterprise of the Southern Jiangsu National Independent Innovation Demonstration Zone. If you are interested in our diffusion welding machines, please contact us at liuyiyu@jshaifei.com.
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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