fish eyes

[newbie]

I was wondering if someone would be able to tell me the cause of fish eyes at the ends of welds. I call them fish eyes but I'm not sure if that is the right term that is what I was told they were by my welding instructor.
I have a couple of pictures of whta I am talking about. notice the crator on the end of my welds, is this a bad thing? I am welding in spray transfer I can't remember the settings at this time but it is hot so I can weld fast. I am in production and am needed to pump out a lot of these parts in a short period of time.
is there anything I can do to fix this problem, is it a problem? I fear that this will form cracking or that when it gets to the customer they will reject the parts due to this.
Can anyone help me out? I would greatly appreciate it.

 

[newbie]

another question I have if I may ask it is why is it that at the end of a weld it goes flat, that it doesn't have the same bead formation as the rest of the weld.

 

[Sparkey]

What do you mean exactly with fish eyes? the small bubble at the end of your weld? sorry but your pics aren't that clear....

 

[newbie]

ya my camara isn't all that good, I am refering to the dot that seems to always end up on the end of a weld. It is sunk in the weld sometimes covered up with "glass" but on most of my welds there is an indent dot on the finish.
Also the finish of my weld is always flat it doesn't keep the same form as the rest of the bead it just flattens out, is this ok/normal or is it bad

 

[Sparkey]

My guess would be the "fish eyes" come from the fact that when you finish the weld you pull away the torch before you loosen the trigger....(if that makes any sense??)
I'm a production welder myself (car parts) and i would say your welds look fine!
Also try to keep your torch as clean as you can!
How many parts do you have to make?

 

[Paul.]

When the gas shuts of at the finish of the weld the molten metal is attacked by the atmosphere leaving a crater, you need a bit of post gas flow and slope down and wait until the metal has solidified before moving the torch away, if your machine doesn't have a post gas control you'll have to learn to fill the crater by backstepping slightly at the end of the run.

 

[matt1978]

Its actually because the center of the weld is the last bit to solidify, when its freezes fast a small crack/hole can be caused, you can over come it by weaving back into the weld when you want to stop or if your using a non transformer based machine, activate the crater fill/downslope facility.

 

[Damaged]

I get the same thing at the end of my welds.

Is it an issue or is it just cosmetic?

 

[newbie]

"My guess would be the "fish eyes" come from the fact that when you finish the weld you pull away the torch before you loosen the trigger...."
Yes Sparky that did make sense, thank you...

TIG Paul when you say if my machine doesn't have post gas flow (it doesn't) I will have to learn back stepping slightly is this what matt1987 is refering to whe he says to weave back into the weld?

I am not too sure what is ment by down sloap either I have a feeling it is obviously just weld on a slith decline but I am not sure.

And I have order after order for these parts I have to weld hundreds last I was told we have close to 1000 pcs to do by year end.

Thanks guys for your help so far,

Should I go back over my other parts and just tack over the end of my welds for the ones that have this "fish eye/crator"??

 

[matt1978]

I get the same thing at the end of my welds.

Is it an issue or is it just cosmetic?

It depends on how critical the welding is..........it is a defect and if it was a weld that was placed in a high stress/load envoironment then it could lead too a failure, but I doubt it is so it nothing to worry too much about

 

[Paul.]

TIG Paul when you say if my machine doesn't have post gas flow (it doesn't) I will have to learn back stepping slightly is this what matt1987 is refering to whe he says to weave back into the weld?

I am not too sure what is ment by down sloap either I have a feeling it is obviously just weld on a slith decline but I am not sure.

Yes exactly the same as what Matt is saying, downslope fades the arc out gently instead of cutting it off instantly, nothing to do with torch or work angles.

 

[newbie]

since this is an issue how do you fix the it because my part will be under extream vibrations and some stresses.
and on my new welds I will now weave back over my finish instead of just stopping.
Thanks again Guys!!!