In arc welding, throughCurrent Waveform ModulationSwitching between short-circuit and jet transition is the core technology for controlling the droplet behavior. The following analysis is carried out from three dimensions: the physical mechanism, control strategy, and material adaptability.
I. Principle of Current Waveform Modulation Technology
Short Circuit Transfer
Waveform Characteristics：
Low frequency, high pulse width(Frequency: 10-50 Hz, Pulse Width: 80%-90%)
Base Current（I_baArc-stable combustion maintenance (50-200A)
Peak Current(I_peak): Instant boost for explosive droplet ejection (>1000A, duration <1ms)
Physical Process：
Melting contact to molten pool → arc extinction → short-circuit current generates electromagnetic contraction force → droplet explosion → arc reignition → repeats cyclically.
2. Jet Transfer
Waveform Characteristics：
High-frequency, low-pulse width(Frequency: 100-500Hz, Pulse Width: 20%-40%)
Constant high current>300A, paired with pulse waveform
Arc Force ControlAxial arc force is generated by wave-shaped modulation to propel molten droplets.
Physical Process：
Melting droplets脱离weld wire under arc force → jet into the molten pool as fine particles → no short circuit occurs.
Control Strategy for Transition Mode Switching
| Control Parameters | Short-circuit Transition | Jet Transition |
|---|---|---|
| Peak Current | Low (rapid decay after explosive melt droplet) | High (Maintaining Arc Rigidity) |
| Pulse Frequency | Low (Matching Pool Oscillation Frequency) | High (Control the frequency of droplet detachment) |
| Duty Cycle | High (Ensure complete melting of droplets) | Low (Reduce Heat Input) |
| Arc Voltage | Dynamic Adjustment (Variable with Arc Length) | Constant (via waveform feedback control) |
Key Switching Logic：
By monitoring arc voltage and current changes in real-time through PLC or Digital Signal Processors (DSP), the system immediately switches to high-frequency pulse waveforms to suppress short circuits when a short-circuit trend is detected. When it's necessary to enhance deposition efficiency, it transitions to a constant high-current waveform to promote jetting transition.
Section 3: Material Scenario Adaptability Analysis
Short-circuit Transition Applicability Scenario
Material Type：
Cold-rolled steel (thickness < 3mm), galvanized steel, high-strength low-alloy steel (e.g., DP steel, TRIP steel).
Welding of aluminum alloys (such as 5xxx, 6xxx series) thin plates.
Process Advantages：
The welding process is stable with spatter less than <1%.
Low heat input (<1 kJ/cm), suitable for heat-sensitive materials.
Welding speed up to 1.5m/min, suitable for automated production lines.
Typical Applications：
Welding of car body roof and door inner panels.
Assembly of home appliance casings (such as refrigerator side panels).
2. Jet Transition Applicable Scenarios
Material Type：
Medium-thickness steel plates (thickness > 6mm), stainless steel, nickel-based alloys.
Titanium alloy (requires pulse waveform controlled heat input).
Process Advantages：
Deposition efficiency > 95%, welding speed up to 2.5 m/min.
The melt depth/melt width ratio is greater than 1:1, suitable for all-position welding.
Excellent arc stiffness, capable of welding downward vertical seams.
Typical Applications：
Deck longitudinal seam welding (plate thickness 12-25mm).
Ring Welding for Pressure Vessel (SA516 Gr70 Steel)
Nuclear Power Plant Pipeline Welding (316L Stainless Steel)
Waveform Modulation Technology Advances
Intelligent Waveform Generation：
Based on neural network algorithms, automatically optimize waveform parameters according to the CTOD (crack tip opening displacement) characteristics of the base material.Multimodal Composite Waveform：
Combining the stability of short-circuit transition with the efficiency of jet transition, achieving the "hybrid transition mode."Spectrum Feedback Control：
By monitoring the arc spectral characteristics (such as the FeⅠ 639.4nm line intensity) and adjusting waveforms in real-time, we compensate for interference caused by changes in welding position.
This technology, which controls the droplet behavior through current waveforms, showcases revolutionary potential for arc welding in emerging materials such as aerospace aluminum-lithium alloys and automotive hot-formed steel.
