Hi all,

I have a happy problem deburring aluminum. Through reduction in cycle times (with lots of help from you here in the forums), our operators are having problems keeping up with deburring the parts within the cycle time of the machine. The burrs aren't any worse than they were before. There's just not enough time to do everything they need to do.

We make life support valves (scuba, scott air pack) complete from forgings off of this machine. Lots of mounting surfaces, cross holes, blind holes, etc from .460" down to .015". Surface finish callouts on sealing surfaces, etc. Basically, the whole part needs deburred.

Most of the cross holes are done on two different passes. That eliminates being able to go back into the first hole to clip the burr. Thus far, i've gotten the operators to use an abrasive grit wheel brush on external burrs. I have brought in abrasive grit internal brushes (I used to work at a brush manufacturer) to do some internals.

And we're still not keeping up. From what in understand (dimly), tumbling this sort of part may be out of the question as my burr problems are all internal and pretty small diameters.

We have a SurfTran thermal deburring system here, but the aluminum needs cleaned afterward. The acid baths here blacken the parts that would show thru the grey oxide. Does anyone know of a way to clean soot off of aluminum without using acid? or an acid that wouldn't blacken the part?

I've also got another change coming that should take another 5 minutes off of the cycle time. Like i said before, this is a good problem to have.

Anyone have any ideas?

Thanks in advance,
Tony

If you are running steel product through the same combustion chamber as you are running aluminum, that may be the root cause of your discoloration. The residual iron oxide will adhere to the aluminum. Have you looked into investing in a separate combustion chamber exclusively for your aluminum product?

We only run brass and a little aluminum-silicon bronze thru the SurfTran. It's set to run those only and does a wonderful job of vaporizing portions of my aluminum valves.

After turning two setup pieces into slag, i found out three things...
1. the acid does not discolor the part as much as previously feared
2. there were some external burrs even after traumatizing the valve body
3. the settings to run brass *might* be a bit high for aluminum

The thing that bothers me most is that there are still burrs. I mean, this body looks like it took a shot of plasma right into the side. There's a dime-sized pocket at least 0.1" deep and splatter/reweld everywhere. The rest of it isn't even burr-free. What's up with that?

I'm afraid all of my experience with the thermal deburring method is with wrought material. Is it possible that the porosity of the aluminum casting is somehow allowing the combustion to "traumitize" your part? Is the part fixtured in some way that would mask any of the surfaces from the combustion, thereby allowing burrs to remain on one segment of the part, while damaging other segments?
Good luck and keep us posted on your progress.

The parts simply sit in a spring basket. The whole chamber is open around them.

Someone here knows a thermal deburrer who does aluminum, but they're a vendor. However, if i can get the cycle down enough to cover the cost of them doing it, it's a win-win situation.

My favorite feature on my nuked valve bodies is the eraser-sized piece of aluminum buried into the threads. Looks like a meteorite impact. That chunk came from the valve next to it.

What about tumbling? anyone know if this is not a suitable part?