Waveform analysis for MIG / GMAW "dip-transfer" mode

These welds were performed on 5mm steel plate with 1.2mm diameter steel MIG wire and Ar/20%CO2 shielding gas.

Sample rate 10kHz
(10thousand measurements of V, I and wire-feed-speed recorded every second).

Dip transfer - a common representative condition

180A 18.7V

A current of 180A is at the top of the range in which dip-transfer is used, according to contemporary practice (writing in 2017).

Overall view

First sample - 0.1s and 0.01s

Second sample - 0.1s and 0.01s

Fairly much as expected. Assuming zero-volt regions are duration of "dipping"/short-circuiting:

• the "dipping and arc'ing" is indeed cyclical at a rate of about 180 per second
• "short-circuiting" ("dipping") visible - volts go to near-zero for ~1/1000th of second (around +4.5V - the Ohmic V-drop?)
• current rise - with steady upward slope during the "dip" (the short-circuit) due to inductance (or simulation of by inverter power source)
• current fall - with steady down-slope when "dip" breaks also due to inductance (or simulation of)
• voltage sustains at an arc voltage as current stabilises to around 120A for arcing phase

Other datalogging performed indicates this example shown is representative.

R D Smith, May&June 2011, 12Jun2017