spray transfer

By swnorris (****)

Date 04-20-2004 13:50

Spray transfer is the result of a pinch effect on the molten tip of the welding wire. Pinch effect on the welding wire is one of the most important factors in controlling metal transfer. Pinch effect governs the shape, size, and rate of transfer. The pinch effect controls the separation of molten drops of metal from the welding wire, thus physically limiting the size of the molten ball that can be formed on the end of the welding wire, which results in droplets of metals transferring rapidly through the welding arc from the wire to the workpiece. The droplets produced are equal to or smaller than the diameter of the welding wire, and are transferred axially at a rate of several hundred per second. For a given wire diameter, the effect is proportional to the square of the current. The amperage must be above the critical value related to the wire diameter. A minimum of 165 amps is needed to achieve spray transfer. Start out with at least 24 volts. An 80% argon gas mixture is needed (set to at least 20/CFH), and DCEP is almost always used. You should be able to get into spray mode with your machine. Keep in mind that other parameters for spray transfer apply such as recess the contact tip behind the end of the gas nozzle by at least 1/8 inch and let the wire stick out 1/2 to 1 inch.

By Lawrence (*****)

Date 04-20-2004 14:47

Tex,

Try www.weldreality.com

Ed Craig runs this site and not only provides parameters, he also offers excellent advice on when each transfer mode is best applied.

The parameters and schedules you will find for spray transfer are the same ones in Ed Craigs excellent textbooks. It's the most best free information focused on mig welding on the net.

By cmansonite (*)

Date 04-21-2004 11:44

Great link Lawrence. That is the most, and useful, info. I have seen on the web for a while. Now if I can retain all of that without my head exploding is another issue.

By texarc

Date 04-21-2004 12:34

Thx for the link bud Im understanding now.

By swnorris (****)

Date 04-21-2004 13:38

The AWS has a publication that may be of interest to you called "The Everyday Pocket Handbook for GMAW and FCAW" for $12.00, or $9.00 for members. This is only one in a series of these "everyday" handbooks. This one has a lot of good information such as shielding gases for spray transfer, globular to spray transition currents, and typical arc voltages. In our shop in the stair/handrail department, we weld carbon steel using .035 wire with 98% Argon, 2% oxygen, @ a minimum of 165 amps. I became aware of these handbooks after an outside inspector was in our shop and used them to check the parameters on my welding procedures for SMAW, GMAW, and FCAW. I don't know what your application is, but if you don't have access to one of these handbooks, I'd be happy to send you the parameters for a particular application. Also, I need to point out that in my last posting, I should have said that a minimum of 80% argon is needed for spray transfer, rather than say 80% is needed.

By texarc

Date 04-21-2004 15:23

Thx, I think ill order the book im trying to stay active on building a liebrary that cover as much as posible. I want to be versetile in as many proceses as as I can.

By jwright650 (*****)

Date 04-21-2004 15:30

I have Ed's book that covers MIG and Fluxcore, it is worth the money.
John Wright