Differences in Principle: Different Energy Control Methods
Constant pressure mode is like a seasoned driver using cruise control-the voltage remains stable, and the current automatically adjusts according to the resistance. During welding, if the pipe expands due to heat, causing a decrease in resistance, the current will naturally increase to compensate for the heat. Constant current mode, on the other hand, is like a precise metronome; the current intensity always remains at the set value, while the voltage automatically adjusts according to resistance fluctuations, ensuring a constant heat input per second.
Applicable Scenarios: Materials and Environment
Constant pressure is more suitable for thin-walled components: When the pipe wall is thin, the material heats up quickly and has a small heat capacity; the self-regulating characteristics of constant pressure can prevent localized overheating.
Constant current excels at thick-walled welding: When dealing with thick-walled pipes, a constant current ensures continuous and stable heat penetration into the deep materials.
Environmental Adaptability Comparison: Constant current mode is preferred for construction sites with large voltage fluctuations, while constant pressure mode has a higher tolerance for pipe ellipticity.
Differences in Effect: Weld Quality
Constant pressure welding produces a more uniform joint appearance, but may produce microscopic pores due to current fluctuations; constant current welding results in denser weld crystals, typically with 5%-8% higher mechanical strength, but requires more precise preheating. In terms of operational difficulty, the constant pressure mode has a larger margin of error, while the constant current mode requires strict control of the pipe fitting connection accuracy and clamping force.
