I have been welding cylinder heads with a Miller Dial Arc for about 10 years, it works ok but it is a little slow. About two years ago we bought a Dynasty 300 Dx and every head I weld has porosity problems. I was not convinced that it was the machine until yesterday. We hooked the old Miller Dial Arc back up and weld a head we were having problems with and it welded great. I have tried changing the frequency from 20 to 120 and the balance from 50 to 85. I feel like it is something in the heads that is being drawn out. I can weld new mat'l with no problem. I have no problems passing my certs on aluminum. This is a very expensive Investment to set aside and go back to the old Dial Arc.
Lonny,
Take a shot at this forum and ask your question.
www.millermotorsports.com/mboard/
It's a hangout for us Miller owners, and there is a lot of good info to get. Hopefully, the resident expert (Andy) will get you an answer.
Hank
Hey Lonny, Welcome to the forum
Having Beta tested Dynasty for Miller I can help you trouble shoot.
Start by making your Dynasty equal to your Dialarc:
60 Hz.
Balence 50-60...... Just a normal wave.
People get pretty jazzed up about these new inverters but the fact of the matter is that for work like your describing their is no real advantage unless the casting is massive and you chuck the Dynasty and buy an Aerowave.
Route the crack until 100% clean.. Verify with FPI or red dye
Go back to the big tungsten and forget the max clean settings. Most Castings require every bit of cathodic etch they can get.
If it's still bombing out look for a bad torch or wet argon.
The advantage to Dynasty is, Light weight, Small Footprint, and extended balence control and frequency that will allow for slimmer bead profile in *thin groove welds* and smaller profile fillets.
The extended capabilities of balence control found in Dynasty must be compensated for with extra efforts to achieve perfect or near perfect surface prep or the whole thing backfires. There is no free lunch :)
The moral of the story is; On old dirty old castings, what worked best before is still best, the principals haven't changed. Dynasty will do it.. Just not any better.
Write back and let us know how the whole thing turns out in the end.
On this particular head I am welding it had receiver O-ring grooves around the combustion chambers. We are filling them in and resurfacing so we can use a different style of head gasket.
The first time I welded them with the Dynasty, we rough milled them and it had pitting. While I am welding with the Dynasty I can see bubbles forming just under the surface and then they will pop. There does not seem to be anything visible coming out. There is no sooty black evidence left in my bead.
I went back and re welded the head around two of the grooves with the Dial Arc and re welded the other two grooves with the Dynasty Set at 50 Hz on one and 20 on the other. After rough milling, the two welded with the Dial Arc had only a couple of pits, where as the two welded with the Dynasty is still unusable.
There are many other adjustments on this machine that I know nothing about beside Balance and Frequency. Is it possible something is not set properly?
I used the same bottle of Argon on both machines but different torches, is it possible the torch has a problem? This torch makes exceptional welds on new material; I guess that might rule out the torch?
We have experienced far more pitting in our welds since we put the Dynasty into use. Im not knocking the Dynasty though, I do have to say that on everything else it welds really well.
Check gas flow system for Dynasty. It seems a shielding problem.
Good luck!
Gong
Thanks, I have not tried a different regulator and lines. Good tip!
Please check torch size also. Bigger torch nozzel diameter has bigger shielding area. Are your torches the same size?
Both machines have same torches with same gas lens and cup...
New test this morning.
Started with a scrap head.
I machined the head surface clean.
I welded the head with the old set up.
110 Freq.
75 Bal.
2% Ceria Tungsten
The moment the puddle forms you can see bubbles forming and opening to the surface. The bubbles do not seem to go away with time.
I went ahead and layed a bead. The bead looked clean from the outside with no visible signs of pitting.
I then switched regulators and line. It seemed to weld the same.
Next I removed all of our torch quick disconnects and installed a brand new torch with all new parts directly to the machine. I still see bubbles forming.
I then took a carbide burr and cut a trench 1/4 wide by 1/8 deep and removed some of the surrounding material. as soon as a puddle starts I see bubbles.
I set the balance to 50 and the frequency to 60. It welded slower but still bubbled.
I just went and remachined the deck surface to check the welds for pitting. All of the welds had about the same amount of pitting.
I have put the head back in the oven. Im going to raise the temp to 450 deg. to see if it affects the welds.
I tried heating the head 450 deg. and it help temendously. I use to heat the heads to 350 deg. with our Dial Arc and it worked fine. But I think the reason it worked was because it welded so slow that by the time it started to form a puddle it had the head considerably over 350 deg.
Now I just hope that taking these heads to 450 deg. does not compromise the heat treat of the head?
I guess we will see.
Thanks for the the help.
There's a lot of thinking when we weld
Just think this problem through with the info you have obtained.
One of the main reasons to use a Dynasty is to keep the heat down.(pulse, wave balance). In many situations, that could be a good thing-but not with heavy castings.
You need to "boil" the inpurities out of your weld area. This takes heat and torch manipulation. It may take a weld-grind weld sequence.
The inverters will do this if set up correctly with a zirconiated tungsten and slow welding parameters. If you are lucky enough to have a squarewave type machine, be sure it is set to max penetration to reduce the amount of impurities pulled out of the base metal.
Keep us posted...
Good Luck
brande
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