Mig issues or not?

[Davek0974]

Trying to figure out if i have an issue or not, not been happy with my welds for some time now, can't remember how long. These are all on 3mm bright mild, various wire speed and voltages.

The welds always seem high to me, i have never managed to get a concave surface, always proud, just varying degrees of proud.

Gas is Hobbyweld5 @ 9lpm, indoors welding on an R-Tech I-Mig160 with 0.8mm ER70s6.

Straight butt weld stringers....





Fillet with a circular weave...


Fillet with a left/right whip...


The whip pattern looks ok to me but considering this a 3mm sheet fillet, its very big and wide.

I can never get a bacon sizzle either, there is always a cracking or crackling sound - much more pronounced than a sizzle. I have today tried just every combination of voltage and feed speed and a sizzle was never to be heard. The arc-force knob seems best left mid-way.

So, using these pics what am i looking at here? I'm not looking to get coded, I make garden brackets etc so 'reasonable' would be the target i think.

 

[backpurge]

You won't get a concave surface with MIG but do agree the welds are too convex, have you tried travelling faster with no weave, try and keep the wire right on the front edge of the weld pool, maybe turn the wire speed down a tad as well

 

[Sparkey]

Totally agree with Backpurge and try not to jerk away your torch at the end of the bead that causes the small pinhole at the end....post gas setting would be nice, does your kit have that?
Other than that it looks very neat and tidy! Better than some of the welds we come across on that garden stuff you can buy at the stores (too expensive too!)

 

[Davek0974]

So,not really as bad as i thought then

I will try lower wire feed and high travel speed tomorrow, see what that does. Also pausing at the end as well.

No variable post gas, its fixed at around two seconds i think.

 

[Richard.]

You can control the bead very easily with mig and changing settings. As BP said you won't get a concave face on a mig run but you can make it flatter/wider and blend in the toes by either increasing voltage/decreasing wire speed. Picking up the travel will reduce cap height so I entirely agree with the posts above. No need to weave. For me pic 2 looks perfectly fine.

 

[Davek0974]

Ok, had a bit more play this morning, tried going bit faster and got this result - seems not too bad i think?



The dial settings used above gave me a feed rate of 170" / min which seemed low?

The i recalled reading on here that i need 40A per mm so i checked the display while running a bead and it was only 98A. The chart says 3mm is 20-23V and i was on 20v so i upped the wire feed until i got 120A and things started sounding a lot better, also a lot hotter. I will need to adjust my motion to suit but I got this result....



And trying the same settings on one of my brackets - 3mm x 16mm hot rolled, certainly looks better than i have been getting....



After that I tried reducing the voltage and feed but keeping the dials the same offset/distance apart and it works, it sounds better and looks better I think?....



Now, if these are indeed better ? Then it seems I just did not have the dials at the right setting - On my machine, the manual said set the feed pointer to the same as the voltage pointer so I was pretty much doing that but the sweet spot is with the feed two sections higher than the voltage.

To keep it simple I have moved the feed dial knob to rebalance the two so now i can set both equal and get good results at any voltage setting - seemed like a good idea. I can now use the chart for voltage based on metal thickness and easily get the feed to match, or at least close starting point.

I also blew the liner out with air and checked the feed unit out but all seemed good.

 

[Richard.]

I tend to work 30 amps/mm ish for fillets like your doing go a little more and outside corners a little less. It's very rough and varys a lot from unit to unit and person to person.

 

[Davek0974]

That would likely be about right, the first pictures were at 40A/mm or 120A but the last one was after I reduced the voltage and wire feed in the same proportions, i will check the A value out next time I'm in the shop but i bet its close to 90-100A now, but with the wire feed in the correct proportion to the voltage.

 

[Davek0974]

Just found the page I read last night - a rough setting along with 40A/mm material is supposedly (with 0.8mm wire) 2x the current in inches per minute so i should have got around 240" of wire but I was only running 170" (17" in 6s) so Another indicator i was running outside the expected parameters. The data was on weldingtipsandtricks site.

Also of interest was a recommendation to cut the shield so the tip is proud or level, mine is recessed inside the shroud - anyone done this here????

 

[Davek0974]

that does look a little 'off'

 

[Davek0974]

Been doing some more welding, 3mm again, this is a 350mm long run on the outside of a five-sided flower planter, they are made up of ten interlocked triangles with pentagons top and bottom.



Here's a finished one, they will be galvanised to finish.


I weld up with a heavy bead then grind back to restore the corners, a lot of weld and grind, takes about three hours to make one.

I think the welds are ok now??

 

[Davek0974]

Ok, new gas supplier now, regarding weaving, on the left is a straight run, right is gentle weave, same feed and voltage, 3mm mild with a scale coat.

This is a joint I do a fair bit of on some of my products, seems ok I think? - 45deg fillet at at 45deg angle, 3mm mild, 110A, I tend to get best results running top->down.

Butt joint, 3mm mild, 115A, got a bit hot where the metal was cut away.

Lap joint, 3mm mild, 115A

What do you all reckon ?

It does sound a little better on the BOC gas, definitely not as much yellow soot and having the gauge all the way round feels good too, should last a bit longer.

 

[Norm]

Any pics of the finished article in the latter pictures Dave? they're interesting shapes and a decent cut if your plasma cutting them freehand.
regards Norm

 

[Davek0974]

Any pics of the finished article in the latter pictures Dave? they're interesting shapes and a decent cut if your plasma cutting them freehand.
regards Norm

Here you go, not freehand though, CNC cut.

 

[Norm]

Thanks, very nice job,

 

[super noob]

You could try 15% CO2, you'd get higher penetration so odds are the weld would be flatter

 

[Davek0974]

That would be somewhere between Argoshield universal (12%) and heavy (20%)

I cant get these mixes on the hobby deal I'm set up for, only the Light version which is recommended for 0-4mm steel.

 

[super noob]

It'll be hobby weld 15, I used to get real nice welds with pure CO2, bit more spatter though so you needed to use the anti spatter spray to make sure it didn't stick (or cooking oil spray)

 

[T0rnado69]

when i was getting prices the other week at my local BOC,
he said that universal is on the hobby deal too.

 

[cliff366]

I wish my welds was that good and I wasn't happy lol I'd be printing them of and hanging them on the wall if they was that good