Resistance welding and laser welding are two widely used joining technologies in automotive manufacturing, each offering distinct advantages for specific applications.
What is Resistance Welding?
Resistance welding is a method in which workpieces are joined by applying pressure through electrodes and utilizing the resistive heat generated by the current passing through the contact surface and adjacent areas of the joint. The primary methods of resistance welding include four types: spot welding, seam welding, projection welding, and butt welding.
What is Laser Welding?
Laser welding involves irradiating the workpiece surface with a laser beam, where the surface heat diffuses inward via thermal conduction. By controlling parameters such as laser pulse width, energy, peak power, and repetition frequency, the workpiece is melted to form a specific molten pool. This technique is widely adopted by automotive manufacturers for welding roofs to body structures due to its advantages in aesthetics, noise insulation, and sealing performance.
Advantages of Resistance Welding
Resistance Welding relies on electrical current and mechanical pressure to create coalescence between metal sheets. It is highly efficient for high-volume production, particularly in body-in-white assembly, where it joins stamped steel components. Common variants include spot welding and seam welding, known for their speed, cost-effectiveness, and suitability for thin-to-medium gauge materials.
Advantages of Laser Welding
Speed: Laser welding significantly outperforms resistance spot welding in terms of speed. For instance, a 1-meter-long weld can be completed by laser welding in 6 seconds, whereas resistance spot welding can only produce a single spot weld in the same timeframe.
Seam Integrity: Laser welds form continuous linear joints, eliminating the risk of water leakage inherent to discontinuous resistance spot welds. This allows the omission of the sealing adhesive application process.
Dimensional Precision: The reduced distortion in laser-welded joints minimizes step differences between metal panels, enhancing body precision. It also facilitates the joining of steel plates with varying strength grades.
Whose strength is higher?
The laser-welded joint is a narrow, continuous straight line, while a resistance spot-welded joint comprises a series of discrete circular points. The weld metal in laser welding undergoes rapid solidification, resulting in a finer microstructure that enhances mechanical strength. Consequently, the strength of laser-welded joints marginally exceeds that of resistance spot-welded joints.
