[jtybt]

I have been practicing aluminum with the Everlast 225LX and my practice looks acceptable enuff to try a project.

These are 3/8" thick plugs that will be fitted to the holes and recessed down about 3/32" and filled to block off the water passages.





The big problem I get is contamination from the cast aluminum and the biggest so far has been a big crater in the left hole that didn't want to fill. I drilled it out but that didn't work...couldn't get the heat down there so I grooved it out. and went from 1/16" to 3/32" tungsten 126 amps and capped it off.

How do you get a crater to fill way down deep instead of just getting it to cap?


Thanks for any help


100% argon at 10-12 liters with both #6 gas lens and #8 straight cup...and foot peddle.

[gnabgib]

Are you pre-heating the casting?

[jakeru]

I'm hoping to learn how to master this problem as well, so I will add what I've learned so far, and hopefully others will too to help us all get further educated.

I'm working on an cast aluminum intake manifold, modifying it to fit another engine application, and it has not only oxide inclusions, but some really nasty flux inclusions (from a previous attempt I made at this by oxy-acetyelne welding, which didn't work so well... before I got the TIG). The flux inclusions when melted with a TIG torch are like little pieces of glass, they melt into little red glowing hot spheres under the heat of the arc. Before being melted they are whitish powder, like salt. One melted they are brittle, glass like and black in color and are easily physically removed by scratching them away with something sharp.

Other aluminum oxide nastiness is best physically removed by scratching and scraping. If I can scratch/scrape to shiny aluminum at the bottom of a crater, I most often will have success of the crater filling. I hand wire brush (stainless bristles) what I can but this won't clean in the crater. If any bits float up out of the crater, I stop and scrape those off to keep it clean. Those dark, black bits (maybe heavy oxides?) when welding that sometimes float up are the really nasty stuff, and are best remembered where they are, stop welding, and scraped away.

To do the scraping, I have been using a utility knife (where it can reach) and small drill bits to reach a bit deeper into craters. The goal when craping is to get shiny "fresh" aluminum at the bottom of the crater. My latest idea is to get a set of dental picks (you know, intended for cleaning plaque off teeth) as I think they might work really well for scraping crap out the bottom of a crater, or deep crevice.

I am holding the tungsten down in the crater as far as I can without touching. The idea is to focus the heat on the bottom of the crater. I am sticking it out far enough to see easily past the gas cup. The sharpened, tapered tungsten is helpful for reaching down as far as possible into the crater. Before striking an arc I touch the tungsten at the crater bottom, lift up a tiny but, then strike the arc and not being shy at all with the current on the foot pedal. I have ample sharpened tungstens ready to go for when I get mine contaminated. (I am using 3/32" I think on my cast aluminum, I would use 1/16" on a thinner material, as long as the end is not melting.) I stick it out far enough to see easily with good clean test results. I test new settings, and clean minor contamination off the tungsten, by firing up with a blast of high current on a scrap piece, of fairly high travel speed (no filler rod added), then stop the arc, observe that not more carbon/soot is being blown into the surface. (Quick stainless hand wire brush off any carbon.) This helps me make sure my settings and tungsten are good and ready to go. I am using lanthanated tungstens (but haven't really tried anything else.)

My inverter machine (a now discontinued, Everlast "Super200P") settings I found most successful for floating out crap and filling craters are ones that maximize the penetration and focus of the arc. I am using 30% cleaning action, max current (footpedal controlled). High frequency pulsing seems helpful for arc focus and maybe even for agitating the puddle a bit more too. I run the pulse frequency max'ed out (300 Hz, which you can hear "singing".) My machine doens't have adjustable AC frequency, a "square wave" / inverter type. I run the "pulse off current" setting at minimum, the "pulse on duty cycle" between 50-75%. When welding, I like to start hot with footpedal down all the way and not be shy with welding current but try to focus it down deep into the crater (think, try and make get the crater bottom "liquid shiney"), that is usually what works to fill the crater.

I can't wait to buy a set of dental picks because I have a really deep crevice I need to weld on this intake manifold project, and I don't know how else I'll even clean it! I can't even reach a hand wire brush anywhere close.

I've got to get a new bottle of gas, and will consider a helium mix if the price is affordable. I've just been running 100% argon so far.

[jtybt]

Thanks, That helps.

[jakeru]

I picked up some dental scrapers (dentists call them "scalers") from my last dental visit (would you believe that they just throw old ones out?), and have given them a try for cleaning aluminum for welding.

Although it is a little laborious to scrape large surfaces with them, they work well for scraping out sand, old flux, and other crap out of deep pockets, craters, and crevices, where other tools will not reach.

[tigamajig]

i run alot of cast aluminum and magnesium with a synchrowave tig,..to purge this contamination and oxidation , you will need to adjust the arc balance to a "clean" setting. this will push the "dirt" to the leading edge of the puddle....add filler closer to the center when you backstep your arc, don't add to the edge or you will be folding crap back to the crater....you also would benefit from the use of small (toothbrush sized) STAINLESS hand brush, everyone should know that a steel brush deposits oxides...you don't want that. you should preheat with a low amp arc,i don't use a torch on Al, stop 1/2" shy of the finish,brush off the dirt,finish out clean.

[jakeru]

Thanks for your input on this, tigamajig! In my experiments with varying with cleaning (EP/EN) %, I recall finding there is a point where further increase of EP% will not help (but does make the tungsten much hotter where it can melt its sharp tip, and gets less heat/penetration at the work.) However maybe some more experimentation is in order.

I now believe the glowing orange hot "spheres" (which cool to a dull gray) I have encountered from time to time are little pieces of old casting sand, which would explain why they simply don't melt, float and wet out over the aluminum. After they've cooled off, they also seem very brittle and not physically connected very well to the aluminum, so can be quite effectively scratched out of a crater/pocket, if you can reach a metal tool down in the pocket (drill bit, utility knife, or dental scraper.) If one of these glowing spheres is sitting down in a crater/pocket, you might be able to cover aluminum up over the top of it, but you can't really fill the crater/pocket with solid aluminum until removing the sphere.

The other main "nasty contamination" I am seeing seems to sometimes float up out of a crevice/crater up to the surface, and looks black/dark in color under the arc, but then cools off to (slighly rough textured) an aluminum color. It is also really tenacious stuff, scratching it with a hand wire brush doesn't remove it. DCEP doesn't seem to phase it either. Sanding (cartridge roll), or grinding (carbide burr) is effective in getting rid of it (as well as some of the good aluminum underneath.) Hand scraping with dental scraper or utility knife also works, but is a lot more effort. My best guess is due to the aluminum-like color, that these are heavy aluminum oxides. I wonder if they are caused by an old flux pocket that corroded the aluminum over time (which is present on this particular cast piece), or if it was from old hydrocarbons (greases, oils) in the pores (this is an old automotive intake manifold) coming across from the back side.

I switched to welding on a different piece of cast AL (another intake manifold, from the same manufacturer), and it went very easily / smoothly. The weld puddle wetted out nicely pretty much everywhere. Seems to be a better casting quality (no casting sand/oxide inclusions) and cleaner too than the casting I have experiences problem with.

Shielding is critical too and I feel I have recently gotten better at getting reliable shielding too.

Thanks for your help brainstorming.

[tigamajig]

SHARP TIP ?.....imho a sharp point does not produce the best arc for soft alloys, i grind/sand the electrode with a blunted point, like you wold for a "scratch start" machine, some of the oldschool guys i've worked with put the pol.switch (synchrowave 180 )on a/c and flashed (2 seconds-15-20 amps) a ball-up tip every time they welded aluminum....cast or sheet, but i don't like the big ball....and it heats the shielding cups so hot that they crack.
.
.
.
. ...so i tried a small cone profile, and a medium stickout 1/4",and low flow on the gas 12 cfh...and it works for intake risers and pump housings and a transmission case or two....ranging from 1/4" thick up to 5/8" (multipass)

[jakeru]

What size cup are you using, tigmajig? And are you using a gas lens or standard collet body?

I am putting a small flat on the end of my tungsten tips now, like maybe .010" wide. I tried totally sharp, and found a tiny molten ball forms on the end without much current at all. With a high % DCEN (high penetration, low cleaning setting) a small flat allows the tungsten to take much more current than a totally sharp (IE: blood drawing) tip, before the tip of it melts.

[tigamajig]

call me chris.i use std collet.and alum.(red)cup....almost all the repair work and gen fabrication allows for the 7 or 8 cup, but i have been in some spots where only a 6 with some length knocked off (and a short back on the other end) would fit....
.
.
.also...
.
.
.
I have recently changed shop/company , and will not be working on aluminum much at all.my job also involves a lot less repair work and absolutely no more GARBAGE TRUCKS ,irrigation pipe ,or pontoon boats!...