SHINHOP laser

Is your battery still using resistance welding? Let's see what the difference is with laser welding! If your battery welding manufacturing is still using resistance welding, you will be eliminated by your peers, as everyone is now starting to update to laser welding machines. Why? If you still don't understand, please read this article, it will clearly tell you the difference between resistance welding and laser welding. For users who have not come into contact with laser equipment, don't miss it. Let's start discussing the characteristics and differences between laser welding and resistance welding.
In addition to the different appearances, laser welding and resistance welding are two different concepts in welding technology. Laser welding refers to a welding method that uses laser as the heat source, distinguishing it from arc welding, resistance welding, electron beam welding, etc. It has two modes: continuous welding and pulse welding, and laser welding can also be spot welding. Spot welding is a method of welding that differs from seam welding. Generally, resistance spot welding is widely used. Compared to laser spot welding, both have their advantages and disadvantages. Laser spot welding does not require pressure, can achieve greater penetration depth, and is easier to automate, making it a trend in development.
Resistance welding is one of the traditional welding methods, with relatively low technical content. The welding quality and application range are limited due to its working principle. With the continuous development of welding processing technology and the increasing market demand for welding quality, the emergence of laser welding meets the high-end welding needs of enterprises and completely changes the processing method of welding. Its pollution-free, radiation-free welding method and efficient, high-quality welding technology ensure that it will be the only choice for future welding processing technology. So where exactly is the difference between laser welding and resistance welding? Let's first understand what resistance welding is and its advantages and disadvantages.

1. Definitions of Two Welding Methods:
Resistance Welding: A manufacturing process and technology that joins metals or other thermoplastic materials such as plastics through heating. After the workpieces are assembled, pressure is applied through electrodes, and welding is performed using the resistance heat generated by the current passing through the contact surface and adjacent areas of the joint.
Laser Welding: Laser welding is a high-efficiency, precision welding method that uses a high energy density laser beam as the heat source, characterized by being contactless, pollution-free, and radiation-free.

2. Equipment Classification
1. Resistance welding equipment is classified by welding process into four types: spot welding machines, projection welding machines, seam welding machines, and butt welding machines. It is classified by power supply method into: single-phase AC welding machines, secondary rectifier welding machines, three-phase low-frequency welding machines, energy storage welding machines, and inverter welding machines.
2. Laser welding equipment is classified by welding method into: spot welding, continuous welding, butt welding, and stack welding. It is classified by light output method into: pure fiber laser welding, hard light path fiber transmission laser welding, YAG laser welding, and semiconductor laser welding.
3. Classification of Resistance Welding:Resistance welding methods mainly include spot welding, seam welding, projection welding, and butt welding (resistance butt welding, flash butt welding). 1. Spot welding is a resistance welding method that assembles the workpieces into overlapping joints and compresses them between two cylindrical electrodes, using resistance heat to melt the base metal and form weld spots.
1. Spot welding is mainly used for thin plate welding. The process of spot welding is as follows:
① Pre-pressing to ensure good contact of the workpieces.
② Power on to form a molten core and plastic ring at the welding point.
③ Power off and forge under pressure, allowing the molten core to cool and crystallize under continued pressure, forming a dense weld point without shrinkage holes or cracks.
2. The process of seam welding is similar to spot welding, except that a rotating disc-shaped roller electrode replaces the cylindrical electrode. The workpieces are assembled into overlapping or butt joints and placed between two roller electrodes, which apply pressure to the workpieces and rotate, supplying power continuously or intermittently to form a continuous weld seam. Seam welding is mainly used for welding structures with regular seams that require sealing, with a plate thickness generally below 3mm.
3. Projection welding: Projection welding is a variant of spot welding; it forms one or more molten cores at the joint in one operation on a workpiece with pre-formed projections.
4. Resistance butt welding: Resistance butt welding assembles the workpieces into butt joints, ensuring their end faces are in close contact. It uses resistance heat to heat them to a plastic state, then cuts off the power and quickly applies forging force to complete the welding. Resistance butt welding is mainly used for workpieces with simple cross-sections, diameters or edge lengths less than 20mm, and lower strength requirements.
5. Flash butt welding: Flash butt welding assembles the workpieces into butt joints, connects the power supply, and gradually brings their end faces closer to achieve local contact. It uses resistance heat to heat these contact points, generating a flash under high current, melting the end face metal until the end reaches the predetermined temperature within a certain depth range, then cuts off the power and quickly applies forging force to complete the welding. The joint quality of flash welding is better than that of resistance welding, and the mechanical properties of the weld seam are comparable to those of the base material. Moreover, there is no need to clean the pre-weld surface of the joint before welding. Flash butt welding is often used for important weldments. It can weld the same type of metal or different types of metals; it can weld 0.01mm metal wires as well as 20000mm metal rods and profiles.
4. Disadvantages of Resistance Welding:
1. Currently, there is a lack of reliable non-destructive testing methods. The welding quality can only be checked through process samples and destructive tests of workpieces, as well as various monitoring technologies to ensure quality.
2. The overlapping joints of spot and seam welding not only increase the weight of the components but also create angles around the molten core of the two plates, resulting in lower tensile strength and fatigue strength of the joints.
3. The equipment has high power, and the degree of mechanization and automation is relatively high, leading to high equipment costs and difficult maintenance. Moreover, commonly used high-power single-phase AC welding machines are not conducive to the balanced operation of the power grid.

▲ Battery Cell Laser Welding Machine

5. Advantages of Laser Welding:
1. It can reduce the heat input to the minimum required amount, with a small range of metallographic changes in the heat-affected zone, and the deformation caused by heat conduction is also minimized.
2. Workpieces can be placed in a closed space (under vacuum or controlled internal gas environment).
3. It is easy to perform high-speed welding with automation, and it can also be controlled digitally or by computer.
4. If using perforated welding, the depth-to-width ratio of the weld can reach 10:1.
5. It is not affected by magnetic fields (which can easily affect arc welding and electron beam welding), allowing for precise alignment of the workpieces.
6. A wide range of materials can be welded, and various heterogeneous materials can also be joined together.
7. No electrodes are required, eliminating concerns about electrode contamination or damage. Additionally, since it is not a contact welding process, wear and deformation of the equipment can be minimized.
8. No vacuum is required, nor is X-ray protection necessary.
9. A switching device can transmit the laser beam to multiple workstations.
10. When welding thin materials or fine wires, there is no issue of re-melting as seen in arc welding.
11. The welding process parameters for single-pass welding of 32mm plate thickness have been verified and can reduce the time required for thick plate welding, even eliminating the need for filler metal.
12. The laser beam can be focused on a very small area, allowing for the welding of small and closely spaced components.
13. The laser beam is easy to focus, align, and guide with optical instruments, can be placed at an appropriate distance from the workpiece, and can be guided around equipment or obstacles surrounding the workpiece, while other welding methods cannot perform due to the aforementioned spatial limitations.
14. Laser welding can weld two or more metals with different properties (such as different resistances). In terms of welding advantages, quality, cost, and efficiency, laser welding far surpasses traditional resistance welding. Its application range is also quite broad, making it an essential configuration for future welding processing. Its only drawback is that the purchase cost is relatively high, but its production efficiency and benefits are unmatched by any other equipment.

Resistance welding in battery welding is limited by high speed and welding quality, making automation difficult, resulting in higher production costs and greater radiation. It can no longer adapt to the development of new energy battery technology in the new era, nor is it suitable for the special needs of dust-free workshop production. The welded battery cells cannot enhance market competitiveness and are already being phased out. Therefore, manufacturers still using resistance welding for battery cells must adopt green, environmentally friendly, and convenient laser welding equipment to develop in the future. Only by continuously updating your production equipment can your products go further. In addition to battery cells using laser welding, the current booming power battery market is also the same; laser welding assembly lines have become the preferred welding manufacturing equipment for industry development!
[This article is compiled from the internet for reference and learning purposes.]