What do you do with your "waste" material?

[Ricardoco]

Agree with Jazz here, you hardly get anything from melting down the swarf as the surface area to volume ratio is so high and the surface is aluminium oxide which obviously doesn't melt.
I take the swarf to the scrap place and keep the offcuts for when I eventually get round to melting it....

Again i agree but im not sure that a max of 5nm of oxide per surface is the problem if your chips are cut correctly rather the burn off.

[Jonathan]

At school we once tried melting down a significant amount of aluminium turnings and it was a complete waste of time - lots of slag and not much else.

Again i agree but im not sure that a max of 5nm of oxide per surface is the problem if your chips are cut correctly rather the burn off.

I heard that it's the oxide layer formed when the swarf heats up in the furnace that's the problem, as it's significantly thicker than what is formed from the lower temperatures during machining. If the however the swarf was plunged into a molten pool of aluminium, then it does not make (much) contact with oxygen whilst hot, so cannot oxidise further. This does present a safety hazard though if the swarf is wet or has oil on it which is pretty likely...

[Ricardoco]

At school we once tried melting down a significant amount of aluminium turnings and it was a complete waste of time - lots of slag and not much else.



I heard that it's the oxide layer formed when the swarf heats up in the furnace that's the problem, as it's significantly thicker than what is formed from the lower temperatures during machining. If the however the swarf was plunged into a molten pool of aluminium, then it does not make (much) contact with oxygen whilst hot, so cannot oxidise further. This does present a safety hazard though if the swarf is wet or has oil on it which is pretty likely...

Im sure your more academiclly qualified/capable than I am to comment on the subject but as i said, the burnoff, as you add it to the heated empty crucible it almost evaporates in a puff of smoke, even if you shove in a tightly packed bundle it just goes Pooof!!!! Blimey Not sure ide try the plunging into molten ali though, I have poured molten from 1 crucible to another crucible full of swarf, although it didnt seem to increase the volume by any noticable amount it didnt go up in a puff of smoke either, I was once told never cold to hot... Maybe there is truth in that LOL.. But The scrap bits that arnt swarf are IMO worth making ingots from.