Chip Welding

[SteveM]

So if you have had the misfortune of loading a cutter up with chip welded aluminium is there any way of removing the aluminum from the cutter?

On a lathe tool, I have use a chisel or screwdriver and knocked it off.

Steve

[Harold_V]

So if you have had the misfortune of loading a cutter up with chip welded aluminium is there any way of removing the aluminum from the cutter?

Speaking from the position of having "enjoyed" chip welding under varying and strange circumstances, as I know better, yes, you can remove the accumulated chip, but the damage will have already occurred, and you may not have the opportunity. I say that because if you're running in aluminum at acceptable speeds and you happen to get chip welding, you often have but a moment to stop the cut before you lose the end mill (along with the part being machined). We used to see that happen occasionally when the Gorton Tru-Trace equipped mill was running parts where I was trained.

Back to end mills that have experienced chip welding---one of the problems is that when the welded chips are removed, the end mill often has embedded residue that encourages further chip welding. That problem can be addressed by applying proper lubricant and taking light cuts, which often dislodge the embedded aluminum. A short, sharp scriber can be used to get under the welded chips, working in the flute, starting from the shank end of the end mill.

Using a four flute (or more) end mill is an invitation to the problem, as they tend to have limited chip clearance, so they perform poorly when loaded with a heavy cut, something that's very easy to do with aluminum if one has the least sense of how freely it machines.

Bottom line---stick to two flute end mills and don't cut dry. No real need for flood coolant---you can accomplish the task with an acid brush and kerosene or WD-40. And, if your machine is rigid enough, take climb cuts instead of conventional cuts. If you can't climb when roughing, make sure you do for finishing. Makes a world of difference in the end result.

Harold

[ctwo]

I think it was actually 3-flute end mills that were suggested to me, for the CNC.

[mcostello]

Drano or lye removes Aluminum with no harm to steel. Added oven cleaner.

[Glenn Brooks]

Just had an interesting experience with chip welding - sort of outside the envelope of the usual concerns with cutters and end mills etc.

My boy and I were cutting some thin aluminium plate to fabricate brackets for an awning on his RV. As I don't work in Aluminium, really didn't have any way to cut the material. So found a package of metal cutting jig saw blades and commenced to hack off the necessary 4' x2" strips needed for a supporting piece. In no time the fine tooth metal blades were encased in aluminum and useless. One broke. The other was completely clogged up to a fine smooth finish - totally useless for cutting. I stripped the Aluminium off the second and found the teeth were so degraded it wouldn't cut even when clean.

Finally, sort of with no other options, I put a coarse tooth wood blade in the jig saw, - like 1/4" wolf teeth. This blade zipped through all the remaining cuts with no problem. No chip loading. Little chatter, and it's still good to go.

Quite a learning experience!

[SteveM]

Finally, sort of with no other options, I put a coarse tooth wood blade in the jig saw, - like 1/4" wolf teeth. This blade zipped through all the remaining cuts with no problem. No chip loading. Little chatter, and it's still good to go.

It was probably acting as a nibbler rather than a hacksaw.

Steve

[Harold_V]

I stripped the Aluminium off the second and found the teeth were so degraded it wouldn't cut even when clean.

Better than even chance the blade was just carbon steel, not HSS, which would not have been dulled by heating. Carbon steel readily loses hardness when over heated, which you did by allowing the blade to attempt to cut when it was fully loaded with chips. This is an excellent example why one should lubricate cuts, with the intention of preventing chip welding.

Harold

[Glenn Brooks]

Harold, yes, am sure it was not HSS - just garden variety hardware store jig saw blades. But we were in a pinch and it got the job done. I used lubrication on every operation after that with almost no chip loading. Simple hand held spray bottle of diesel fuel worked well. Aluminium certainly is a different material to work with than steel.

Glenn