What controls penetration?

Date 08-15-2002 02:28

I have been welding at a joist manufacturing plant for about four years. I make the butt splice welds in the joists chord. I leave 1/2 the thickness of the material as a gap. You would think a company like this would have a welding "expert" somewhere but they dont seem to. I have shown several welds to other welders after welding just one side and not getting the amount of penetration I want. (Less than 1/2 the way through) I have been told to turn up the wire speed, turn down the wire speed, turn up the heat and some combinations of the above. I think turning up the wire speed results in "false" penetration of metal oozing into the gap. Seems to me that when i turn up the heat I get more penetration if everything else stays the same. "Speed" welding seems to be the thing in a production shop as the more we produce the more we get paid, however I have seen a bunch of guys keep turning up the wire speed thinking it makes them weld faster. I have found turning up the heat seems to allow me to advance the wire faster. Who is correct? Most welds I am talking about here are either in the flat or a 45 degree position welded downhill. I would like to hear some of your thoughts.
Thanks in advance

By overthehill (*)

Date 08-15-2002 03:35

What process are you using, solid wire, flux core with gas, or flux core without gas? What type of shielding gas? How thick is the metal? What type of welding machine? What are your Voltage and Wire Speed settings (even the approximate position of the dial, like 1 o'clock, if your not sure)? Your right, the company should have some parameters established.

By oldkid

Date 08-15-2002 23:08

Well I guess it would help to include all the info!
Using Lincoln 655 on 460 3-phase power. Shielding gas is argon I am not sure of the %. Wire size is .045 Material thickness is .212 Volts are set on 25 and wire speed is 350. Both speed and Volts have been recently calibrated.

I spoke with our Quality assurance manager today who does all the certification testing of newly hired welders and cuts out welds (off the production line) from time to time and does a destructive test. He stated we have a voltage minimum and maximum allowable for our wire size (22-29 for.045) but says this is just the wire manufactures suggestions or reccomendations or something like that. He said the Volt setting (See I didnt say heat) and wire setting are up to the individual welder and he knows of no "average" settings for material thickness etc. I bet this provokes some comments! Wow thanks for all the response.

By dee

Date 08-15-2002 15:14

Proper parameters for GMAW process can be determined knowing the wire size, shielding gas, and metal type & thickness.

Maximum speed can be achieved in spray transfer; practical if you are hand welding flat >1/8" or vert down <3/8" thick steel... I may be off on the vert down max thickness. Time spent in mastering the technique is amply rewarded by notable speed and penetration benefits.

It would also be somewhat helpfull to verify the OCV with a Volt meter as well as to verify the wire feed rate... it only takes a couple minutes, but it insures that you really are providing power IAW the laws of physics that govern welding processes, and not merely trying to.

On a tangent;
You are right in trying to understand what is going on with your welding parameters.
The common use of "heat" to describe the volt setting is confusing if you try to apply it to those laws that concern electricity. There is no "Watt" adjustment knob. If you think of a static shock you get from walking across a carpet, the voltage could easily exceed a thousand Volts and yet there is no real harm done to your finger. If you think of your fuze box and the fuxes or breakers calibrated in Amps, and how the old type fuzes actually heated to where they melted (or "fused") you would more correctly understand what actually determines the heat in an electrical circuit such as a welding arc. The feed control of a GMAW power supply adjusts the amperage in a calibrated proportion to, and along with, the speed of the wire feed.

I think of it like this:
Arc physics determine what adjustments in the volts or amps will actually accomplish; the shielding gas acts to modify the arc physics according to its composition, and the diameter of the electrode determines the amount of energy necessary to reach a given level of transfer, or physical reaction, within the arc.

There are various combinations of adjustments to these variables that may serve to make an acceptable weld; only one is optimum and best serves all your important interests and concerns.

A complete and accurate comment on who was right about parameter adjustments is not a short one.
With this in mind, a conversation with an expert in sloving exactly the kind of industrial problems you are experiencing would be a help, and doing so is convenient; log on to www.weldreality.com, explore everything, which should clarify some issues, and post appropriate questions under the thumbs up/thumbs down icon ("weld questions", opinions, or something like that). I suspect solving the problems at the plant will involve more than merely truning a knob on your welder, but it translates into take-home pay.

Regards
d

By Lawrence (*****)

Date 08-15-2002 16:50

Bravo!

Thank you for the excellent analogies.

By dee

Date 08-15-2002 17:04

Thanks for the words
d

By stich585 (*)

Date 08-16-2002 05:06

Damn, I am impressed. Really, from all the answers I have seen you give I am impressed. Smart, Proffesional. you really do know what you are talking about. Steve.

By stich585 (*)

Date 08-16-2002 05:07

Talking about Dee.

By dee

Date 08-16-2002 22:38

thanks Steve and any others I am waxing humble

By oldkid

Date 08-17-2002 04:41

Thanks for the link to weldreality. It cleared up a whole bunch of misconceptions I had and made a lot of sense. Even ordered some training material.