Before bringing a laser welding machine into the workshop, many business owners ask the same question: "Can this machine do spot welding today and long seam welding tomorrow?" The answer is—not only can it switch, but it can also "change the laser light as needed" within the same weld seam. The key lies in the type of laser, the control software, and the openness of the interface. Below, we'll explain the mainstream technical routes, switching methods, and key points to avoid pitfalls, so you won't be confused by the term "mode switching" when buying equipment.
Ⅰ. Distinguish between the three types of "light": pulsed, continuous, and quasi-continuous.
| Laser type | Peak power | Typical pulse width | Suitable for process | Switching flexibility |
| Pulse YAG/Fiber Optic | 10 kW Class | 0.1–50 ms | Spot Welding, Splicing, Thin Plate Pulse Sealing | ★★★★☆ |
| Continuous fiber optic | Smooth output | No | Long seam, deep penetration, high-speed welding | ★★☆☆☆ |
| Quasi continuous QCW | Low duty cycle high peak | 0.05–10 ms | Can be spot welded and continuous, peak ≈ 3 times continuous | ★★★★ |
In short: If you want to switch between spot welding and continuous welding with a single click, QCW or a continuous laser with pulse modulation is the best choice.
II. Hardware Level: The laser itself must support "dual-mode" operation.
Continuous laser with "pulse gating":
Cutting continuous light into 1–100 ms square waves can simulate spot welding, but the average power drops sharply at low duty cycles, reducing penetration depth.
QCW Quasi-Continuous:
Peak power can reach 3–5 times the rated average power, providing sufficient spot welding sparks at 0.1 ms. 100% duty cycle converts to continuous welding without hardware modifications.
Composite laser (continuous + pulsed dual-channel): High-end models have built-in dual laser modules, with software routing switching < 50 ms, simultaneously satisfying "deep penetration long seam + pulsed spot welding" within the same program.
III. Software Level: A Good Controller Makes Switching Seamless
Waveform Library Recall: Pre-stores 20+ waveforms including spot welding, continuous welding, spiral spot welding, and gradual arc initiation, with a switching time of < 30 ms.
Power Ramp: When switching from continuous welding to spot welding, the power can drop to 10% within 0.2 ms, avoiding a "volcano" effect at the end.
IO Trigger: Real-time forced mode switching via PLC or robot DI signals facilitates mixed-flow production within the same fixture.
One-Click Teach Pendant Switching: Some brands have made "spot welding/continuous welding" a shortcut soft key, allowing workers to complete the changeover in 3 seconds without modifying G-code.
IV. Real-world Case: On the same production line, spot welding → continuous welding → sealing welding is completed in 55 seconds.
Workpiece: Side panel of a new energy battery module
Configuration: 6 kW QCW fiber laser + three-axis gantry + servo clamping
Breakthrough:
Pulse spot welding positioning: 12 points, single point 0.3 ms, peak power 6 kW;
Switch to continuous mode: power 3 kW, welding speed 1.5 m/min, long seam 400 mm;
Final switch back to pulse mode for sealing welding of 8 points to prevent cracking.
Results: Three modes are completed in one clamping operation, switching delay < 0.1 s, weld pass rate 99.5%, cycle time 3 times faster than manual three-step process.
V. Avoidance Guide: Don't Let "Fake Mode Switching" Ruin Your Budget
Adjusting Duty Cycle Only ≠ True Switching: With a continuous laser, the peak value remains unchanged at low duty cycles, making spot welding prone to pore breakage.
No Real-Time Feedback: Lacking power closed-loop control, the actual energy drifts by ±15% after switching, resulting in poor weld consistency.
No Robot Synchronization Interface: Switching signal delay > 200 ms, by which time the robot has moved, causing incomplete welds at the beginning of the weld.
No Waveform Library License: Some brands support this on their hardware, but the software is charged per "waveform package," costing 20,000 RMB per mode, leading to explosive long-term costs.
VI. Conclusion: With the right laser and controller, "instant switching" in spot welding/continuous welding has become standard.
Overall, the QCW quasi-continuous laser + controller with waveform library is currently the most economical and flexible "dual-mode" solution.
For high-volume, complex processes, a composite laser + bus controller can infinitely mix spot welding, continuous welding, and spiral welding in a single process, with a switching time of < 50 ms, almost imperceptible.
If you have welding machine requirements, please contact Ms. Zhao
E-Mail: pdkj@gd-pw.com
Phone: +86-13631765713
