GLOBULAR OR SPRAY TRANSFER?

By Mike Brown Date 11-21-2002 19:32

I understand the difference between the two modes of transfer but at what point does globular become spray transfer? Does shielding gas matter or make the difference between the two? I have heard many "stories" on both but still cannot find a by the book reference to make a parameter distinction between the two. Any info on this would be of great help. -MB-

By jwright650 (*****)

Date 11-21-2002 20:20

Mike,
In a gas shield of at least 80% argon or helium, filler metal transfer changes from globular to spray as welding current increases for a given size electrode. For all metals, the change takes place at a current value called the globular to spray transition current. There is a chart in the AWS Welding Handbook Vol II. 7th edition(Table 4.2) that gives the transition currents for different electrode types,sizes and gas mixes.
Hope this will help,
John Wright

By dee

Date 11-22-2002 04:43

All you seek can be found at http://www.weldreality.com, including references (offered for sale) covering the subject in depth. Give yourself several hours to thoroughly peruse the wealth of information provided.

You will know by looking into the arc at the actual transfer going on, the sound, the lack of spatter, high deposition rate and the fluid weld bead characteristics...

...but I believe John's different answer was indeed the (W)right one to answer the point of your question, no?

(you may need a bit darker shade for your shield lense to actually see the arc detail if it gives you difficulty)

Regards,
d

By George-kh (**)

Date 11-22-2002 13:54

I believe if you see a spray arc you will get your answer.
Use 290 to 310 amperes and 29 to 33 volts with a mixture of (82% Argon + 18% CO2) shielding gas and with wire AWS: ER70S-6 (EN: G3Si1) diameter 1.2 mm.
Spray arc is almost without spatter.

By jwright650 (*****)

Date 11-22-2002 18:08

When you are Spray transfering the metal dropplets are smaller than the electrode you are running(more current), When you are Globular transfering(less current) the dropplets are the same size or larger than the electrode. At the point you drop the current to where the dropplets get to be the same size as the electrode, that is what is called the transition current or vise versa(add current until until it goes from globular to spray).