mig welding

Date 03-17-2004 20:26

Hi mo,
What size wire, what gas mix and cfh flow are they running on the machine you are testing on? Also give the voltage, wirespeed(ipm) or amps. Some one might could help you get in the ball park once these unknowns are supplied.
John Wright

By bmaas1

Date 03-17-2004 20:36

also joint configuration and why can't you adjust the parameters?

Brian J. Maas

By mo64

Date 03-17-2004 20:45

the only thing i know is the wire is 35 i didnt look at the other stuff they said everything was set at what they wanted it to be set to. every time i was there they had alot of people to take weld tests so its a get ya in and get ya out type situation.the tube is hollow rectangles fiting togeather. fit up isnt the best i wish is could draw what it looks like. from the looks of it there are alot of people who burn threw.

By jwright650 (*****)

Date 03-17-2004 21:32

Brian,
I was guessing at it being a fillet around a tube to tube "T" connx.
John Wright

By Lawrence (*****)

Date 03-17-2004 21:14

Ok, here are a couple of tips that will help you get through this interview.

If the employer has parameters that they won't let you change than they must have folks that can make it work. New guys like yourself may have a hard time at first getting used to the pace and positioning that is required but there are techniques that you can use that make a big difference in penetration and you don't have to touch the knobs to do it.

First, use a forehand or push torch angle rather than a drag angle, this will reduce penetration.

Second and most importantly, your mig powersource is a constant voltage *drooping current* machine. Simply stated this means that the longer the "stickout" the lower the amperage will be at the weld. You can recess the contact tip 1/8 to 3/16 inch into the nozzel (if your doing short curcuit transfer) without drawing any attention to yourself. This will allow you to get good gas coverage while increasing your stand off (tip to work) distance slightly. Here is the rule of thumb; longer stickouts with GMAW Short Circuit drastically reduces amperage and therefor penetration. This can allow you to travel a bit slower or reduce your chances of burning up the work, however, too long a stickout will cause spatter and reduce side wall fusion in fillets, so don't get carried away with a long stickout. A little goes a long way.

Increasing your travel speed is the third way to decrease penetration but I'm sure your going as fast as you can. Just keep the pace as quick as possible without loosing control and use the two techniques listed above and you can reduce the penetration and increase your manual control of short circuiting Mig results *without* resetting the controls or touching knobs that the testers don't want touched.

If you know exactly the wire feed speed in inch per minute and the arc voltage along with the type of shield gas that this employer wants locked in, there might be even more tips.

By jwright650 (*****)

Date 03-17-2004 21:28

L,
I think you about covered it.
John Wright

By mo64

Date 03-17-2004 21:29

thanks for the tips im going to take this test again pretty soon and ill see what happens. after i do the test ill post what happened.

By ssbn727 (*****)

Date 03-18-2004 04:57

Hi Mo64!
Lawrence gave you some good tips there!
I just want to add about having too much wire stickout; If your stickout is too long, and you're not allowed to make a slight increase in your gas flow rate (cfh) on your flow meter then, chances are that you'll lessen the amount of gas coverage also which may cause porosity and ruin the weld. Everything that Lawrence mentioned is correct so I'm just including this possibility also.

Are you you able to see the weld pool comfortably and gage the size of the pool clearly without hindering your travel speed? Make sure that you position your head, body, arms and line of sight so that you do'nt limit your full range of motion because many times with someone just starting out, they may overlook this possibility as to what may be an underlying cause of why they're not moving fast enough at certain locations along the joint. Of course, being that none of us can witness your technique, rate of progression or travel speed as you're welding, the actual joint configuration or the specified welding parameters, this limits us in giving you a real good assessment as to what adjustments you need to make when you're welding in the 2, 3 and 4 positions (2=horizontal, 3=vertical, 4=overhead).

One would think without knowing all of the particulars of course, that one would have to make a slight change in the power source (voltage) or wire feeder (amperage) settings in order to adjust for changes in position and still stay within the specified parameters in order to achieve acceptable results for each position but in reality, this is'nt always the case.

Like Lawrence mentioned, if the employer has parameters that they won't let you change then they must have folks that can make it work so, you may need to make adjustments related to your position in observing the weld pool clearly without limiting your range of motion or your travel speed for that matter and incorporate some or all of the tips that Lawrence suggested. If this is indeed the case, then you also might want to use a welding helmet with a larger size lens so that you can observe and maintain your travel speed better which seems to be one of the problems here - if you're able to have access to one from either purchasing one or borrowing one from a friend. Is your vision corrected? In other words do you wear glasses or some other form of vision correction? I ask this because maybe you might need to use a clear magnifying lens (cheaters) in your welding helmet if you cannot clearly gage the size of the weld pool from the distance you're observing the weld pool...

In any event, I wish you the best the next time around and most important of all - be patient because if you're frustrated, you'll lose your patience, do'nt forget to breathe, relax and never give up!!!

Respectfully,
SSBN727 Run Silent... Run Deep!!!

By SA-200

Date 03-18-2004 14:01

If they have the parameters locked, they should tell u the procedure they want u to weld. Like the angle, stickout, travel speed, and weld size. Make sure the diffuser, contact tip, and cone is clean inside and out. GoodLuck!

By jwright650 (*****)

Date 03-18-2004 14:43

To add to what SA said,
In fact they should supply you with the WPS ("welding procedure" it has all the parameters listed, along with the joint prep and dimns) to weld by.
If they don't supply it voluntarily, ask for it.
I forgot to ask if they supply any scrap to run on before welding on the actual test? Seems kinda harsh to ask someone to run a machine they never ran before (with all the controls locked) and expect you to just pull the trigger and go.
John Wright

By mo64

Date 03-18-2004 19:36

alright well here it is i think my problem is that i would pull the gun insted of pushing it, i think next time ill ask them witch angles and all that work best.now for the scrap to practice on befor doing the test they dont do that,they have you tast on the actual part they are makeing at the time (first shop i have ever tested at that did that)but for the most part pulling the gun is probably where i go wrong.i called them today and they said they are only hireing threw a temp place now so it might be a little while before i get my shot at it again(i hate temp places)this place is hireing almost all the time. i think becouse either ppl are quiting or geting caned alot.i think ill send my resume to the temp place tomorrow and see what happens.thanks for the replys i have a feeling things will go alot better this time.(kinda wish i could stick weld it insted,stick is more my cup of tea.)