How to choose welding current for electric scooters

How to choose welding current for electric scooters

Basic knowledge of welding current
Welding current is an important parameter in the welding process, which has a key impact on welding quality, production efficiency and weld formation. Too large or too small current will bring a series of problems. For example, too small current will lead to arc instability, incomplete penetration, slag inclusion and other defects; too large current will cause the welding core to overheat, the coating to fall off, causing weld undercut, burn-through, weld nodules and other problems, and will also increase the deformation of the workpiece and the amount of metal spatter, making the weld joint tissue overheated and coarse, affecting its mechanical properties.

Welding situation related to electric scooters
Electric scooters are usually welded from multiple metal parts, such as the frame, handlebars, forks, battery boxes and other parts that require reliable welding processes. The quality of these welding parts is directly related to the overall performance and safety of the electric scooter, so it is very important to choose the welding current reasonably.

Factors in selecting welding current
Electric rod type and diameter: Different types of electrodes require different welding currents. For example, due to the differences in coating composition and welding process performance, the corresponding welding current ranges of acidic and alkaline electrodes will also be different. Generally speaking, the larger the electrode diameter, the greater the welding current required, because a larger electrode diameter requires more arc heat energy to melt it. The approximate range of welding current can usually be calculated according to the empirical formula I=K×d, where K is the empirical coefficient and d is the electrode diameter. The K value range corresponding to electrodes of different diameters is different.
Weldment thickness: When the weldment thickness is large, in order to ensure that the weld can penetrate, a larger welding current is often required. Because thicker weldments require more heat to melt the metal and fully fuse it to form a strong welded joint. On the contrary, for thinner weldments, the welding current should be appropriately reduced to avoid excessive current burning through the weldment.
Joint type and weld position: Different joint types, such as butt joints, lap joints, corner joints, etc., require different welding currents. Butt joints usually require a larger current to ensure the penetration of the weld, while lap joints and corner joints require relatively smaller currents. In addition, the spatial position of the weld also affects the welding current. Generally speaking, the welding operation in the flat welding position is relatively convenient, and a slightly larger current can be selected; while the vertical welding, horizontal welding and overhead welding positions are more difficult to operate. In order to ensure the welding quality and operation stability, the welding current should be appropriately reduced than the flat welding position. Usually, the vertical welding is 15%-20% smaller than the flat welding, and the horizontal welding and overhead welding are 10%-15% smaller.
Welding level: In multi-layer and multi-pass welding, the base weld needs to penetrate the root of the weldment and form a good weld shape, so a smaller welding current is usually selected; while the filling weld and the cover weld can increase the welding current appropriately to improve the welding efficiency.

Reasonable selection range of welding current for electric scooters
Frame welding: The frame is the key load-bearing component of the electric scooter, and is usually welded with thicker metal plates or pipes. When welding the frame, the welding current can generally be selected at around 150-300A according to the thickness of the material used and the welding process requirements. For example, for a thin-walled steel tube frame with a thickness of 2-3mm, a smaller current, such as 150-200A, can be selected; while for a thick-walled steel tube frame with a thickness of 4-6mm, the current can be appropriately increased to 250-300A.
Welding of handlebars and forks: For the welding of handlebars and forks, since the force is relatively small and the thickness of the weld is generally around 1-2mm, the welding current can be selected between 100-150A. Such a current range can not only ensure the good forming of the weld, but also avoid burn-through of the weld or excessive welding deformation due to excessive current.
Welding of battery box: The welding of battery boxes needs to ensure the sealing and reliability of the weld to prevent problems such as leakage of battery electrolyte. For the thin metal shell of the battery box, which is usually around 0.8-1.5mm thick, the welding current can be controlled between 80-120A to achieve a good welding effect.

The influence of welding equipment and process on welding current
Welding power source type: Commonly used welding power sources are AC power supply and DC power supply. The price of AC power supply is relatively low, but the stability of arc during welding is relatively poor, especially when welding thin plates or when the welding parameters are high. DC power supply can provide a more stable arc, which helps to improve welding quality and production efficiency. When selecting the welding current, it should be adjusted appropriately according to the type of welding power supply used. For example, when using DC power supply to weld the frame of an electric scooter, the welding current can be appropriately increased on the basis of AC power supply to give full play to the advantages of DC power supply and improve welding efficiency and quality.
Welding method: Different welding methods also have different requirements for the selection of welding current. Common welding methods include spot welding, seam welding, arc welding, etc. Spot welding and seam welding are usually used to weld thin plates and small metal components, and the welding current is relatively small, generally between tens of amperes and hundreds of amperes; while arc welding is suitable for welding metal materials of various thicknesses, and the welding current range is wide, ranging from hundreds of amperes to thousands of amperes. In the production of electric scooters, it is crucial to reasonably select the welding method and the corresponding welding current according to different welding parts and process requirements.
Coordination of welding speed and current: There is a close coordination relationship between welding speed and welding current. During the welding process, if the welding speed is too fast and the welding current is insufficient, it will cause defects such as incomplete penetration and slag inclusion in the weld; on the contrary, if the welding speed is too slow and the current is too large, the weld will be too high, too wide, or even burn through the weldment. Therefore, when welding electric scooters, the welding speed should be reasonably adjusted according to the size of the welding current to ensure the quality of the weld. Generally speaking, when the welding current increases, the welding speed should also be increased accordingly to maintain the uniformity and consistency of the weld.

Welding quality inspection and adjustment of welding current
Appearance inspection: After welding is completed, the weld should be inspected first. A good weld appearance should be uniform and smooth, without obvious defects such as undercut, weld nodules, slag inclusions, and pores. If these problems are found in the appearance of the weld, it may be caused by improper selection of welding current, which needs to be adjusted according to the specific situation. For example, if the weld has undercutting, it means that the welding current is too large and the current should be reduced appropriately; if the weld is too high or too wide, it may be that the current is too small or the welding speed is too fast, and the current needs to be increased or the welding speed needs to be adjusted.
Nondestructive testing: For some important welding parts, such as the key joints of the frame, in addition to the appearance inspection, nondestructive testing, such as ultrasonic testing, radiographic testing, etc., is also required. Nondestructive testing can be used to find defects inside the weld, such as internal pores, slag inclusions, and incomplete penetration. If the nondestructive testing results do not meet the requirements, the reasons should be analyzed, among which improper selection of welding current may be one of the important factors, and then the welding current should be adjusted, and welding and testing should be performed again until the weld quality meets the requirements.

Actual case analysis
During the production process, an electric scooter manufacturer found that the welding parts of the frame often had problems with incomplete penetration and slag inclusions, which affected the quality and performance of the product. After analysis by technical personnel, it was found that the welding current was too small. Therefore, they increased the welding current from the original 180A to 220A according to the thickness of the frame material and the welding process requirements, and adjusted the welding speed appropriately. After the improvement, the problems of incomplete penetration and slag inclusion in the frame weld were effectively solved, the welding quality was significantly improved, and the overall performance of the product was also improved.

Summary
The reasonable selection of welding current is crucial to the welding quality of electric scooters. In actual production, factors such as electrode type and diameter, weld thickness, joint type and weld position, welding layer, and the influence of welding equipment and process should be comprehensively considered. Through welding quality inspection and actual case analysis, the selection of welding current is continuously optimized to ensure the welding quality and performance of electric scooters, thereby improving the market competitiveness of products.