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Washout
16-09-2012, 01:07 PM
As I sit here musing over what ballscrew lengths etc I need, my butterfly mind drifted into what am I going to do with all the swarf and offcuts (assuming of course my machine actually manages to cut aluminium ;) ) and what do others on here do with the waste?

Reason I ask is most of the pieces I will be making are going to be fairly complex shapes, milled/routed out of blocks of aluminium and having played about with a couple of CAM programs I'll be doing that out of fairly oversized blocks, so that I can a. have tabs to hold the piece in place within the block and b. drill indexing holes for "dowels" or bolts, so that I can flip the piece for multi sided cutting. This is obviously going to lead to a fair chunk of "waste" aluminium, some of which will probably not be able to be used for smaller parts.

I had this probably crazy idea of melting said waste down into new ingots for refacing and use in other pieces (assuming of course grade (6061/7075 etc) is not critical to the recycled material.

Does anyone know of a facility that does this for a small fee, or is it best to save it up and just get scrap prices?.....thoughts?

Cheers


Chris

irving2008
16-09-2012, 02:47 PM
Not worth saving for scrap... you'd need a lot to make it worth the petrol to take it there...

I'd suggest making a small furnace and making your own ingots. For complex shapes that you plan to make many of its sometimes better to cast the rough shape then machine it; especially if you end up milling out more material than you leave...

Ricardoco
16-09-2012, 03:15 PM
I'd suggest making a small furnace and making your own ingots. For complex shapes that you plan to make many of its sometimes better to cast the rough shape then machine it; especially if you end up milling out more material than you leave...

Thats what i did irving, after all when you first start you do tend to make a lot of scrap lol, 45,000BTU burner, old damaged propane tank,cut for purpose perlite and fire cement liner,1ltr crucible bit of welding and hey presto!!

I will say it does take a lot of chips to make a decent size ingot..

Rick

i will post some pics if i get the time to take them..

Washout
16-09-2012, 04:11 PM
Thanks Guys,

So not so crazy an idea afterall, although the wife will probably have a differing opinion ;-)

I also have a bunch of other reclaimed and "waste" aluminium form other projects and house related DIY I can add to the mix (I'll stop short of cruising the local accident black spots with an engine hoist and cutters).

Would be most interested in your furnace pic Ricardoco.

Cheers


Chris

JAZZCNC
16-09-2012, 06:18 PM
Off cuts melt ok but Swarf or Chips make poor quality cast and it's messy loads of dross, plus like Rico says need lot n lots of them. Best not botherd with IMO just separate and take to scrap when dust bins full.!!

Ricardoco
16-09-2012, 07:03 PM
Off cuts melt ok but Swarf or Chips make poor quality cast and it's messy loads of dross, plus like Rico says need lot n lots of them. Best not botherd with IMO just separate and take to scrap when dust bins full.!! Again i could not agree more, but i did make about a ton of chips before i managed to make anything, I would have cried real tears if i didnt at least try to make an ingot from it Lol...

Rick

Jonathan
17-09-2012, 09:42 AM
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....

Ricardoco
18-09-2012, 09:07 PM
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
18-09-2012, 09:57 PM
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
18-09-2012, 11:30 PM
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.