Hi All, Part of my job is programming MIG welding robots but I leave the setting to the weld techs who were talking about "dip" & "spray" transfer. Can any one enlighten me what they are & why they are used?:
Hi,
From what i remember (maybe) dip transfer means the wire physically dips into the weld pool before melting,whereas spray transfer melts fractionally and gets 'sprayed' across the ionized gap...or i could be talking utter rubbish,there are much more qualified guys on here than me!
Dip or short circuit transfer: The wire hits the weld pool, shorts, melts back leaving drop in pool. Process repeats. This creates the characteristic buzz of short-circuit mode. Works well in all positions, can create spatter.
Spray transfer: The wire melts into small droplets within the arc and these drops are carried by the gas/current to the metal. Spray transfer is nearly silent, just a hiss. This only occurs well in high argon gas mixes (>85%). CO2 becomes instable at high currents and has a low arc current. Typically, spray transfer occurs only in currents greater than 200A.
Spray transfer can be very clean, have a large deposition rate and have a flatter profile on the weld. Since the metal must flow accoss the arc as fluid, it is more difficult on vertical ond overhead welds and is more susceptible to gas turbulence.
Globular transfer is in the middle. A ball of metal forms on the end of the wire, then drops to the weld pool.
Pulse MIGs were developed to create the high current needed for spray transfer while maintaining a lower current and staying out of globular transfer mode.