In the production process of the battery cell of the automobile power battery, the cover plate, the shell and other parts need to be laser welded. If the welding quality is not good, there are bubbles, the welding strength is insufficient, etc., it will cause the liquid in the battery to leak. Significant quality problems will cause safety hazards.
In addition, where friction welding electrodes are used, the welding quality requirements are also very high. Otherwise, it will increase the risk of poor attachment and fall off after welding. At the same time, the resistance caused by grease and cleaning agent residues will increase, thereby affecting electrical performance.
Therefore, the OEM has very high requirements on the welding quality of the batteries, and no bubbles are allowed. However, aluminum parts will be contaminated by various lubricating oils and coolants in the early production, stamping, and cutting processes. If they are not sufficiently cleaned on the cleaning line, or if they are not cleaned, there will be cleaning agent residues, which will increase the failure of the weld. risk.
At present, there is a new detection method that can detect whether there are contaminants remaining in the welding position within a few seconds, quantify the cleanliness of the welding position, and quickly determine whether the part can enter the next welding process. On the other hand, it can optimize production through inspection and collection. Process to improve welding yield.
The degree of contamination on the metal surface is quantified by the German SITA cleanliness meter, and the reading unit is RFU (relative to the total fluorescence, the larger the reading, the more serious the pollution).
Link to this article：Failure analysis of laser welding and friction welding of power battery
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