Problems with tungsten

[Mid Wales welder]

Having problems with my tungsten looking like it is burnt!

 

[Tigman]

try that again !

 

[Engineer1964]

its contamination where its touched the workpiece, sometimes you can simply snap off the contaminated part and re grind to whatever point you want with a grinder or proprer tunsten tig grinder

 

[Mid Wales welder]

I am trying to put a picture up but cant seem to get it to work!

The gas cup is also very dirty and the tungsten seems to have whiskers.

 

[Mid Wales welder]

Fimaly, here's the pic!

 

[shenion]

Is your workpiece clean? The gun can attract the fumes coming off work.

Too small a post flow or whipping the torch away when stopping can cause contamination.

You are using pure argon ?

 

[Mid Wales welder]

I did weld a bit of mild steel in a rush which I ran the grinder over, but guess it must have still been a bit dirty.

Thanks for your replys! I will try turning up the post flow, only got it on about 3-4 seconds, didn't want to waste any gas, that's what I get for being a cheapskate lol! Yeh using pure argon.

Cheers

 

[Paul.]

My guess is poor gas flow and scabby material, possibly a touchdown or two. A picture of the completed weld would complete the story.

 

[Mid Wales welder]

I have the gas at 5lpm, I will try a bit more. Will also try holding the torch in place when I stop welding for a few seconds. Unfortunately I was just running welds on a peace of scrap stainless so no picture of specific welds. I only have a cheapo TIG so will check all of the gas pipe connections. Would it be better to put some PTFE tape on the threads?

 

[hotrodder]

The threads don't (or shouldn't) have anything to do making a gas tight seal, the hose tail should make the seal along the same lines as the male and female radiused seats on regulators/gas cylinders

As Paul a pic of a weld will complete the story. Preferably in focus!

A quick test for gas shield problems is the 'spot weld test'. Paul illustrated it here... http://www.mig-welding.co.uk/forum/showpost.php?p=301703&postcount=34 Stainless is a more sensitive material for this, when swapping out a cylinder i always do something like this before welding something 'real'. As i've virtually always got a gas lens on the torch i'm looking for no discolouration at all

 

[Mid Wales welder]

Thanks for the replys! Sorry its taken me a while to answer, busy weekend! Here is a pic of the welds, there is one spot test weld on the right then a weld with no filler wire at the top and the one at the bottom with filler. I think the gas is flowing fine. I put a new tungsten in before doing those welds, i didn't touch down and it turned out like that. Its all a bit strange! ( i know the welds are a bit wobbly, did it in a hurry lol)

 

[hotrodder]

Unless some joker has swapped your bottle of argon for a bottle of argon/CO2 i'd start looking for a gas leak... leak draws in air when the gas is flowing, the tungsten gets oxidised as result and spits bits of itself into the weld.

Favorites include a dodgy back cap O-ring, a torch assembled ass about face or a leak in one of the hoses (hose clip cut through the line/pinhole somewhere/loose connection to the gas solenoid etc).

 

[Mid Wales welder]

I will check it all tomorrow (not sure how tho!) when I get home. So it that the only thing that will make the tungsten look like that? There is defo gas coming out, have it set at 6-7lpm on the flow meter & have 6second post flow & tungsten stick out of about 3-4mm. What is the best way to check for a leek? Thanks for your replys!

 

[hotrodder]

Pretty much, heat metals in air and they oxidise. Tungsten goes through pretty similar 'heat tint' colours as steel/stainless- grey and scaly follows blues. Contaminating 'em with whatever's being welded will also discolour 'em but typically only the very tip and turn it the colour of the metal being welded like these obvious blobs of stainless... http://www.mig-welding.co.uk/tig-technique/contaminated-tungstens-large.jpg

Start with the O-ring on the back cap- look for damage and/or replace. Assuming the torch is correctly assembled check the insulator for damage- the white spacer between ceramic and torch. Can use a leak detector solution (or soapy water a small paint brush) to check the hoses. A leak between the reg and welder will prevent the system from holding pressure* with the cylinder valve closed. Visual inspection aside obviously the machine needs to be powered up to check the torch lead so worth turning off the HF (to avoid getting a tickle) and unplugging the return lead. If none of that fixes it then post again as it'll be covers off to check the internal gas connections- simple enough but you still need to be careful of what you poke even with the machine switched off


* It's usual for the pressure to slowly drop but if it falls to zero quickly (mins - an hour or so) then you've got a leak somewhere between the cylinder and gas solenoid. A leak between the cylinder and reg won't draw in air due to the cylinder pressure, it'll just waste gas

 

[jonnyBMX]

as above, easiest way to check for leaks is to use a paintbrush to apply soapy water, maybe try all the obvious joints first (these are the weak points as they are joins) if that doesnt come up with any problems start looking at the hose and the torch itself,

hope this helps

 

[Mid Wales welder]

Thanks all for your info, very helpful!! I will check it all over tonight or possibly tomorrow and then post what happend. If I get it all fixed is it ok to use the same tungsten & just re sharpen it or do I need to compleatly cut off the heat tinted part?

 

[Mid Wales welder]

So, i have checked over everything and cant find any leak, however where the hose goes into the back of the machine the case is very cold, not sure if its just because its next to the fan or wheather the leak maybe just inside the machine, so i will open it up at the weekend to check!

I was chatting to someone today and he was saying he has the same problem, stainless welds look grey rather than shiney eveb tho he has checked his machine and everything is fine.
Is there a posibility that i may just need to use a gas lens?
Also, is it a gas leak that causes the heat tint on the tungsten or could it be something else?

 

[Paul.]

A leak still seems to be the most likely cause, where are you measuring your 5lpm, you need to check what you are actually getting at the torch, a pea shooter like this is worth having clickme. lenses wont cure basic problems, in fact for most DC work I rarely use one, pull the side off the machine and check out the connections to the solenoid and the back of the connector where it exits to the torch connector.

 

[Mid Wales welder]

That looks like a handy piece of kit, thanks for that! I have a flow meter on the reg at the mo which shows 5-6lpm. I will check the connections inside the machine over the weekend when i have time.
Just out of interest what could be the other possible cause of grey welds and a heat tinted tungsten?

 

[shenion]

You could plug the torch with a cork and then see if you can find any leaks.