Note: I took the remaining ally extrusions and associated crappy castings down to the recycle centre and got $7.60 AU for it. Definitely the best outcome for this stuff. I also cleaned out the crucible and got a large chunck of dross out of it which had sunk to the bottom. Very strange. Most dross comes to the surface and I noticed that wasn't happening with this. So all in all it was pretty weird and horrible aluminium. A nightmare for back yard casters. Cheers Rob
Well done weighing it in, I might have to weigh in some of my stuff, once you get known people come round with alloy & brass & over the years I have loads not so much bronze but enough to see me out at my age, strange that dross at the bottom of the crucible take care Rob & keep the posts coming!! I'm going over to ozz for 3 months to my daughters I hope Regards Graham.
Just thought I’d let you know, adding approximately 6.5% silicon metal by weight will bring you about to an A365 casting alloy with any 6160 or 3048 extruded/billet aluminum. There are other trace metals (copper, manganese, etc, but for the most part they’re about right, IIRC copper is the only one that would be worth messing with like .1 going .4% or something like that). You can double check this as you see fit. (BS in Mechanical engineering)
The problem is not that its an extrusion alloy. Your extrusions are thin wall with a large surface area to volume. A large amount of oxide skins will stay in the melt and not all float to the top. Theres no easy way to fix this on a small furnace. It doesnt help if your pouring into open moulds, causing air, oxides, turbulence.
I use extrusion for casting a lot. Mostly window frames which is primarily 6061-t6 extrusion. In the melting you lose all hardness it becomes -t0. I demold while the casting is still quite hot. Then quench in cold water. This brings back some hardness, maybe to -t4, and it machines much better. All aluminum can be cast. Cans are about 99% aluminum and no good for machine parts, but good for art pieces. I turn all aluminum into ingots before I use in casting, this gets rid of any impurities from the extrusions. And keep the alloys separated.
Hi Dave, this extrusion was really strange. It tore up and also smeared when machined. The other really wierd thing was that the dross sank to the bottom of the crucible and didn't float on top as normal. There must be some other element in this extrusion that is both heavier than aluminium and also seems to melt at a higher temperature. The dross was silvery looking and quite a lot as one would expect, given the surface area of the extrusions. I double checked for anodising and there was definitely none. Beats me. The recycle centre took it all and paid to do it ;) Cheers Rob
There’s nothing wrong with the aluminum in extrusions. It’s just not suitable for casting, or machining after cast. Mixed about 1:1 with aluminum castings, it’s normally fine. Casting alloys are designed for casting, and extrusion alloys are designed for that. I’ve machined thick extrusions with no problem, but once it’s melted, and cast, the alloy has lost come components and it turns brittle.
I think a lot has to do with the use of the extrusion. If there won't be significant cutting/machining to it, they use an alloy that gets a lot of its internal crystalline strength and structure from the extrusion process itself, orienting the "fibers" so to speak along the extrusion axis. I don't think it's any better or worse than casting alloys, but I suspect by mass, there's a lot more extruded aluminum produced than cast aluminum produced every year, so the extrusion alloys happens to be cheaper thanks to the economies of scale. There are also alloys that have a reasonable compromise between extrusion strength and machinability, but that is a lot rarer. It's been 30+ years since I took classes about this stuff, so take that with a big pinch of salt.
Sounds about right to me. I have read a bit on this over the years of home casting and certain elements are specifically added to make the ally machine grade. Ally is most definitely not all the same and charateristics vary enormously, as does cost I would expect. To try and brew your own version to rectify the problem (as suggested by a couple of viewers) seems like a futile exercise to me, especially as the basic issue is not even clear. Cheers Rob
@@Xynudu Rob, yes, the home caster is better off just sticking to known casting alloys. Without a serious lab, it's just black magic guessing what's actually happening on the molecular/crystalline scale and what properties will result. Cheers!
Extrusions are commonly made from 6000 series alloys which need to be heat treated to attain the required strength & hardness ( & hence machineability). First stage ("solution treatment") involves quenching from about 500 deg. C. Second stage is "precipitation treatment" or artificial age hardening which is a soak at not such a high temp. A couple of hours at gas mark 4 worked for me once!
Great info Rob, I like my truck rim's and motor block castings for melting, I've had nothing but bad luck with extrusion aluminum. Great video, keep'um coming.
I think the problem you are having might be due to extruded sections generally having a heavily anodised surface finish. The anodised surface is aluminium oxide which is simply not melting in your furnace, so as a result it becomes mixed in with the finished casting. The underlying aluminium is probably a good, usable grade (for instance, Bunnings says that it's extrusions are 6063 T5 alloy). If you can remove the anodised surface in some way, either before or during the melting process, you might end up with a much superior end result.
Fun fact, A365 casting aluminum is roughly any extruded 6061 or 3048 aluminum with about 6.5% silicon added by weight. You can still use it if you add the silicon to an extruded/billet batch
How do you add the silicon? Is that something you can buy off the shelf? Surely it's not just sand, that stuff is insoluble isn't it? (Please be gentle, I'm ignorant.)
Conversely I get better scrap prices for extruded, than some other grades, ergo better quality ally, but i guess that does not relate to machinability. but even if this attempt was a failure, I've learned so much from the comments. on a side note a short while ago Silicon was in short supply for steel casting (?) so the price of cast ally soared as it can be extracted from that, so i was told by the yard.
Hi Ian, I took the remaining extrusions and the dodgy cast round stock to the recycle center and got enough for a bottle of decent UK beer, so I was happy. The weird thing with this metal is that 90% of the dross (and there was lots of it) sank to the bottom of the crucible rather than float on top as normal. Very strange, suggesting either a very high zinc content or some other heavier than aluminium component. All in all it was a good demonstration of the variability of scrap aluminium. Cheers Rob
Hi Rob I cast a lot of extruded alloy & have done for a lot of years, I use it to make cast signs, traditional name plaques, .house plaques replica railway signs model steam engine number plates etc & it casts very well, & for those items it's good as you don't machine them as such just fettle them & clean up with abrasive paper then sand blast, etch prime & vehicle enamel paint them & I've turned sprues from them & its just like yours, [crap!!] the reason I use it is I've got vast amounts of it,[free!!] I keep all my cast alloys for important parts that need machining & never mix them. I only once unknowingly put a piece of magnesiium in the melt!! thought it was bondy night [Guy Fawkes night in the uk] I allways do the vinegar test now if I'm unsure.
Thanks for the feedback. Some thicker walled extrusion intended to be drilled and tapped can actually be good grade ally and machine well. It's the really thin stuff that has likely composition issues as the manufacturer isn't interested in the machining requirement. Cheers Rob.
Thanks Rob, that was good info. When I come across extruded aluminium I first try to use it as is, those rectangular sections you showed, for example can offer plenty of strength along it length when used upright.
Hi Benny, those sections are extremely strong in the vertical position. I wondered about putting them aside for fabrication, but they have no wall strength for bolting etc. Cheers Rob
I don't know what the composition of this ally is Harry, so it would be pot luck to get a decent outcome. It's gone to the recycle center already. Cheers Rob
Too many years ago to really think about I spent several years working in an aluminium foundry working with tightly specified alloys. The owner was a metallurgist and possessed a book which listed several hundred alloys, their properties and attributes together with recommendations for use. That book was about 30mm thick. It listed one alloy per page mostly. Changing one component a small amount altered the characteristics enormously. Unless you know exactly what alloy you are working with you will be lucky to get any sort of usable metal.
Hi Phill. Thanks for the comment. What you stated is exactly what I would have expected. Hit and miss metallurgy is bound to fail. Obviously the cost factor is a major determinate when formulating ally to a specific set of minimum requirements. Cheers Rob
I melted down a cast alloy lawn mower deck/base once and regretted it. Terrible stuff to machne. Total waste of time. I've been using Toyota alloy wheel rims with great success for quite a while (they last due to the amount of metal in them). I think they are the best option so far. Real magnesium rims are not a regular consumer item as they get brittle with stress fractures in them over time and are ultimately unsafe for long term use. Cheers Rob
It's a composition issue IMHO. Any extrusion that is thick walled and designed to be drilled and tapped should be OK. It's the very thin walled stuff like this that looks to be a possible issue.
Before you haul that off to the recycle center, have another go. This time, add 5-10% zinc. Hardens it right up. Machinability and surface finish improves dramatically. All that smeary stringy behaviour vanishes. 1% copper (in addition to the zinc) makes it even better.
G'day Rob. I've melted the left over pieces of aluminium cladding and have found it gives too much dross, has a cloudy finish and when solidified has the rough finish you described. I haven't machined it and now watching you I won't bother. Cheers Peter
Hi Peter. The rough sand paper (almost spikey) surface finish rang bells that this was unusual straight away. I was dubious even before I turned it. Ally sure has zillions of variants. I find that scrap alloy vehicle wheel rims are pretty good for this process. Cheers Rob
Hi Patrick. Scrap ally is a mine field. The best option by far is to melt down alloy car wheel rims (all the prominent home casters go this way) or engine castings and know it will be fit for purpose. Anything else is totally suck it and see time. Cheers Rob
I think most extrusions are 600 series and that should be ok if not the best to machine. I'm wondering if it's not just the grade but the heat treatment coming into play as well. Sharp HSS tooling and plenty of speed with coolant might be worth a try too.
Hi Lee. The Banggood inserts work extremely well on ally, so I doubt HSS could improve on that. I use both. I can only deduce that this is really terrible ally to machine. Cheers Rob
Hey Rob, Have you tried using borax during your melts to clear out impurities added to the aluminum? I mix all sorts of aluminums when melting and usually have great results. Might be worth a shot mate.
I've tried all these supposed remedies, but basically it's a waste of time. You need good aluminium in to get good aluminium out, simple as that. The main thing you can do to get a better result is to pour as soon as it's melted and DO NOT overheat it. Cheers Rob
Hi Rob. Very interesting. I was given some off cuts of aluminium frames that are used for solar panels, also extruded. Haven't got around to melting any yet but I will keep it separate from my other cast scrap aluminium after watching this. Cheers, Alan.
Hi Alan. Pays to keep the various types separate until you understand their properties. I was a bit surprised at how badly it machined. Usually extrusions are not this bad, but rarely good. Even the BG insert failed to achieve a decent finish. Cheers Rob
Hi Alan, just a follow up on this stuff. The weird thing with it is that 90% of the dross sank to the biottom of the crucible rather than go to the top as normal. Very odd. I had a close look at the dross but couldn't see anything different about it, but obviously there was some heavier element in it than the plain aluminium. It also is definitely not anodised. I took it all to the recycle center today and got enough for a bottle of 1698 ;) You may be OK with that ally extrusion you have if it is thick enough that it can be drilled and tapped for fabrication, that sounds hopeful, but sample a bit first. Good luck. Cheers Rob
@@Xynudu Hi Rob. That is strange, the dross sinking to the bottom. Converting aluminium scrap into 1698 is a great result 🍺👍👍 The extrusion I have was free so it's no great loss if it won't cast, I can always find another use for it. Cheers, Alan.
Hello Rob, Interesting video, thank you... I was wondering if you mixed some cast and extruded aluminum together would you get something that is useable? Take care. Paul,,
Hi Paul, It would improve it, but you would still have B grade ally. Better to use the good stuff and send the crap to the recycle center for some money. I did that today and got enough money for a bottle of Shepherd Neane 1698. Now I think that's a much better outcome ;) Cheers Rob
I don't drink anything out of cans, so I've never tried melting them. I see people melt them on YT, but rarely see the result if they machine the ingot. Cheers Rob
G'day Rob/Ozyrob. I've melted near 500 cans, son in law provided, the aluminium machined well but the melting process was onerous. Even squashed the cans are bulky with very little product so it takes a lot of time and you loose probably 20% if not more to dross. I have found automotive castings and mags a good supply. Cheers Peter
Hi Peter, I've found that anything with a lot of surface area makes lots of dross. So I'm not surprised. I never bother melting machinings for the same reason. I'm with you on the alloy wheel rims and also Myfordboy is a big fan of them. Cheers Rob
I'd rather say choose thicker material than by cast or extruded, since it all starts out cast, certain alloys are good for extruding or don't work out well as cast in a DIY setting. aeration and small batches can give variable results and make you pull your hair out haha
Interesting topic Rob, hopefully this helps a few home casting people out. Have you ever tried Al cans, I can't imagine they are up to much but could be wrong. Cheers, Jon
Aluminium drunks cans are very poor stock for melting. Firstly they aren't made from an alloy suited to casting and also they have such large external surface area to low volume of metal that excess dross and oxides become an issue.
I can't comment on that Gustavo as I'm not a metallurgist. Obviously they add particular element(s) to make it machinable /smoother when worked. Cheers Rob
Hey Rob, thanks for the foundry tips. Question: I have a large stepped cone pulley, you know like off the top of a drill press, but its quite hollow and I want to fit a bearing or two. I was thinking of melting some alloy and just pouring it in. Will this work? will it shrink and fall out? What are your thoughts?
Hi Max. I would rather machine up a steel centre for the bearings, and press or heat shrink it to fit the ally cone. Use Loctite on it as well. You can pour in molten ally and it can work, although there's no guarantee you won't have problems doing it that way. It will semi melt the pulley near the centre and fuse it all together as it cools. I did it once a long time ago, but can't remember what it was for. Good luck. Cheers Rob
@@Xynudu Just to add my 2 cents: poured aluminium will not attach/fuse to pulley. Oxide film will prevent mixing aluminium between pulley and poured aluminium. Better to machine steel/aluminium insert and press into pulley.
No, definitely not Ian. I shoved one into the molten ally to see if it was coated in any way, but no sign at all, even when it partially melted off the end. It's just not machine grade. Cheers Rob
@@Xynudu I know that when I have welded some aluminium it made it near impossible to machine - like trying to machine chewing gum ! I think it was 6061 T6 and welding it removed the hardness it think . I wonder if adding a small amount of the extruded crap to some of the mag wheel alloy would sort it out ! Might make it useable as a filler so you don’t use as much of the good stuff in the pot .
Thanks for sharing your test results Rob. I wonder if those extrusions are closer to pure aluminum like soda cans? My results from soda cans are a bit like what you ended up with.
I haven't tried drink cans. I always thought they would machine OK, given the ally needs to be maleable to press them out. Once again, drink cans are not machined, so that characteristic is not necessary. It all comes back to cost. Obviously the manufacturer will go with what ever grade is cheapest to do the job satisfactoraly. Cheers Rob
@@Xynudu I can remember a guy on RUclips who melted down several hundred drink cans and poured it into a big rectangular slab, then used it to mill it into the upper and lower receiver of an AR-15 semi-automatic rifle. He did the same with old rifle brass btw. So yes, drink cans should be fine to machine after its been molten & recast. More likely it has to do with the temper or how "clean" it was re-cast (i.e. making sure it takes up as little gas as possible).
I see a lot of guys on YT casting aluminium at way too high a temperature and it's no wonder the end product is full of holes and bubbles. I pour all of mine at the lowest possible temperature and get excellent results (with good ally). Brass is just the opposite and likes to be really hot to get a clean cast. They are the only two metals I've smelted and probably ever will. Cheers Rob
The composition of aluminium alloys is listed in Wikipedia en.wikipedia.org/wiki/Aluminium_alloy Only one is listed as "beverage cans" Grade 3004 97.8% aluminium, 1.2% manganese, 1% magnesium there are so many other grades of aluminium that could be classed as "extrusion" that it is hard to see the wood from the trees. Most castings seem to contain Silicon and magnesium (and many other metals), the ability to add silicon may be difficult due to availability (maybe some computer chips), but copper does not seem to be an important part of the mix. A good solution to using the extruded material could be to add it to casting scrap in small quantities so as not to dilute the silicon content too much in the resultant mix. there appears to be a different section grading cast alloys but this section does not include much about composition. As to the comment about adding copper to the mix it can probably be dissolved in the molten aluminium like sugar in water. (the smaller pieces the better to aid dissolving) The following PDF lists properties of machining aluminium, Heat Treating is listed, wonder if the your casting process may effects the "temper" of the material. Zinc is present in the material they test, so would not appear to be the cause of the machining issues. Machining and Machinability of Aluminum Alloys cdn.intechopen.com/pdfs/13408/InTech-Machining_and_machinability_of_aluminum_alloys.pdf one final thought from someone who has never cast anything (unless you count lead fishing weights) would adding some "flux" to the molten mix get rid of the possible contamination with the anodized finish on many extruded items. Hope this is of some help Chris I have done a little bit more reading about TEMPERING the casting before machining, our it will be really gummy and unstable. It is a mine field, the general advice is IF you can't heat treat the part you should leave it up to 6 months to age or it will be dimensionally unstable after machining. Look on the internet for heat treating aluminium to grade T6, it involves several hours in an oven at 700+ degrees (F I think) and then quenching followed by more hours at 350 degrees (F I think) to "age" the material. That is if you have an oven 😂😂.
Note: I took the remaining ally extrusions and associated crappy castings down to the recycle centre and got $7.60 AU for it. Definitely the best outcome for this stuff. I also cleaned out the crucible and got a large chunck of dross out of it which had sunk to the bottom. Very strange. Most dross comes to the surface and I noticed that wasn't happening with this. So all in all it was pretty weird and horrible aluminium. A nightmare for back yard casters. Cheers Rob
Well done weighing it in, I might have to weigh in some of my stuff, once you get known people come round with alloy & brass & over the years I have loads not so much bronze but enough to see me out at my age, strange that dross at the bottom of the crucible take care Rob & keep the posts coming!! I'm going over to ozz for 3 months to my daughters I hope
Regards Graham.
Just thought I’d let you know, adding approximately 6.5% silicon metal by weight will bring you about to an A365 casting alloy with any 6160 or 3048 extruded/billet aluminum. There are other trace metals (copper, manganese, etc, but for the most part they’re about right, IIRC copper is the only one that would be worth messing with like .1 going .4% or something like that). You can double check this as you see fit. (BS in Mechanical engineering)
Excellent observation.
The problem is not that its an extrusion alloy. Your extrusions are thin wall with a large surface area to volume. A large amount of oxide skins will stay in the melt and not all float to the top. Theres no easy way to fix this on a small furnace. It doesnt help if your pouring into open moulds, causing air, oxides, turbulence.
I doubt that. I've melted ally machine turnings and despite the high dross level, the ally casting turned up fine. This is a composition issue IMHO.
Thanks for the tip I would have chucked it in with the rest and wasted some gas!
I use extrusion for casting a lot. Mostly window frames which is primarily 6061-t6 extrusion. In the melting you lose all hardness it becomes -t0. I demold while the casting is still quite hot. Then quench in cold water. This brings back some hardness, maybe to -t4, and it machines much better. All aluminum can be cast. Cans are about 99% aluminum and no good for machine parts, but good for art pieces. I turn all aluminum into ingots before I use in casting, this gets rid of any impurities from the extrusions. And keep the alloys separated.
Hi Dave, this extrusion was really strange. It tore up and also smeared when machined. The other really wierd thing was that the dross sank to the bottom of the crucible and didn't float on top as normal. There must be some other element in this extrusion that is both heavier than aluminium and also seems to melt at a higher temperature. The dross was silvery looking and quite a lot as one would expect, given the surface area of the extrusions. I double checked for anodising and there was definitely none. Beats me. The recycle centre took it all and paid to do it ;) Cheers Rob
There’s nothing wrong with the aluminum in extrusions. It’s just not suitable for casting, or machining after cast. Mixed about 1:1 with aluminum castings, it’s normally fine. Casting alloys are designed for casting, and extrusion alloys are designed for that. I’ve machined thick extrusions with no problem, but once it’s melted, and cast, the alloy has lost come components and it turns brittle.
Thanks for the input Mel. Cheers Rob
Thanks Rob. Time to throw out all the scrap extrusion I guess.
Good for beer money. Cheers Rob
Great info. Thanks!
I think a lot has to do with the use of the extrusion. If there won't be significant cutting/machining to it, they use an alloy that gets a lot of its internal crystalline strength and structure from the extrusion process itself, orienting the "fibers" so to speak along the extrusion axis. I don't think it's any better or worse than casting alloys, but I suspect by mass, there's a lot more extruded aluminum produced than cast aluminum produced every year, so the extrusion alloys happens to be cheaper thanks to the economies of scale. There are also alloys that have a reasonable compromise between extrusion strength and machinability, but that is a lot rarer. It's been 30+ years since I took classes about this stuff, so take that with a big pinch of salt.
Sounds about right to me. I have read a bit on this over the years of home casting and certain elements are specifically added to make the ally machine grade. Ally is most definitely not all the same and charateristics vary enormously, as does cost I would expect. To try and brew your own version to rectify the problem (as suggested by a couple of viewers) seems like a futile exercise to me, especially as the basic issue is not even clear. Cheers Rob
@@Xynudu Rob, yes, the home caster is better off just sticking to known casting alloys. Without a serious lab, it's just black magic guessing what's actually happening on the molecular/crystalline scale and what properties will result. Cheers!
Extrusions are commonly made from 6000 series alloys which need to be heat treated to attain the required strength & hardness ( & hence machineability). First stage ("solution treatment") involves quenching from about 500 deg. C. Second stage is "precipitation treatment" or artificial age hardening which is a soak at not such a high temp. A couple of hours at gas mark 4 worked for me once!
It's going to the recycling center. Thanks for the info. I will continue to focus on alloy car wheel rims, best so far for back yard ops. Cheers Rob
Great info Rob, I like my truck rim's and motor block castings for melting, I've had nothing but bad luck with extrusion aluminum.
Great video, keep'um coming.
Same here. Stick to what works rather than waste time and resources going down a rabbit hole ;) Cheers Rob
I think the problem you are having might be due to extruded sections generally having a heavily anodised surface finish. The anodised surface is aluminium oxide which is simply not melting in your furnace, so as a result it becomes mixed in with the finished casting. The underlying aluminium is probably a good, usable grade (for instance, Bunnings says that it's extrusions are 6063 T5 alloy). If you can remove the anodised surface in some way, either before or during the melting process, you might end up with a much superior end result.
What type of flux are you using for aluminium casting?
Definitely not anodised. I don't use any flux. I've been casting for decades and know what works.
Fun fact, A365 casting aluminum is roughly any extruded 6061 or 3048 aluminum with about 6.5% silicon added by weight. You can still use it if you add the silicon to an extruded/billet batch
Also, a T5 Heat treatment is easy, and can improve machinability of aluminum
How do you add the silicon? Is that something you can buy off the shelf? Surely it's not just sand, that stuff is insoluble isn't it? (Please be gentle, I'm ignorant.)
Conversely I get better scrap prices for extruded, than some other grades, ergo better quality ally, but i guess that does not relate to machinability.
but even if this attempt was a failure, I've learned so much from the comments.
on a side note a short while ago Silicon was in short supply for steel casting (?) so the price of cast ally soared as it can be extracted from that, so i was told by the yard.
Hi Ian, I took the remaining extrusions and the dodgy cast round stock to the recycle center and got enough for a bottle of decent UK beer, so I was happy. The weird thing with this metal is that 90% of the dross (and there was lots of it) sank to the bottom of the crucible rather than float on top as normal. Very strange, suggesting either a very high zinc content or some other heavier than aluminium component. All in all it was a good demonstration of the variability of scrap aluminium. Cheers Rob
Hi Rob I cast a lot of extruded alloy & have done for a lot of years, I use it to make cast signs, traditional name plaques, .house plaques replica railway signs model steam engine number plates etc & it casts very well, & for those items it's good as you don't machine them as such just fettle them & clean up with abrasive paper then sand blast, etch prime & vehicle enamel paint them & I've turned sprues from them & its just like yours, [crap!!] the reason I use it is I've got vast amounts of it,[free!!] I keep all my cast alloys for important parts that need machining & never mix them. I only once unknowingly put a piece of magnesiium in the melt!! thought it was bondy night [Guy Fawkes night in the uk] I allways do the vinegar test now if I'm unsure.
Thanks for the feedback. Some thicker walled extrusion intended to be drilled and tapped can actually be good grade ally and machine well. It's the really thin stuff that has likely composition issues as the manufacturer isn't interested in the machining requirement. Cheers Rob.
Maybe the reason to collect extrusions is to trade it 2 for 1 for cast from the recycler.
Thanks that's good information 👍
Glad it was helpful!
Thanks Rob, that was good info. When I come across extruded aluminium I first try to use it as is, those rectangular sections you showed, for example can offer plenty of strength along it length when used upright.
Hi Benny, those sections are extremely strong in the vertical position. I wondered about putting them aside for fabrication, but they have no wall strength for bolting etc. Cheers Rob
I have seen people mix some zinc in to the melt to make it a bit better to machine
I don't know what the composition of this ally is Harry, so it would be pot luck to get a decent outcome. It's gone to the recycle center already. Cheers Rob
Excellent piece of advice Rob.
Thank you for sharing.
Too many years ago to really think about I spent several years working in an aluminium foundry working with tightly specified alloys. The owner was a metallurgist and possessed a book which listed several hundred alloys, their properties and attributes together with recommendations for use. That book was about 30mm thick. It listed one alloy per page mostly. Changing one component a small amount altered the characteristics enormously. Unless you know exactly what alloy you are working with you will be lucky to get any sort of usable metal.
Hi Phill. Thanks for the comment. What you stated is exactly what I would have expected. Hit and miss metallurgy is bound to fail. Obviously the cost factor is a major determinate when formulating ally to a specific set of minimum requirements. Cheers Rob
@@Xynudu I found magnesium to be undesirable.. Like cast mower bases some mag wheels.. I guess that's why they call em mags
I melted down a cast alloy lawn mower deck/base once and regretted it. Terrible stuff to machne. Total waste of time. I've been using Toyota alloy wheel rims with great success for quite a while (they last due to the amount of metal in them). I think they are the best option so far. Real magnesium rims are not a regular consumer item as they get brittle with stress fractures in them over time and are ultimately unsafe for long term use. Cheers Rob
Thanks for the heads up I would’ve never thought there would be such a big difference in the quality of the aluminum
It varies enormously, but looks the same. Cheers Rob
Very interesting stuff young man!
I have melted a bit of 6061 (tubing, flats, angles, etc) and it worked fine?
It's a composition issue IMHO. Any extrusion that is thick walled and designed to be drilled and tapped should be OK. It's the very thin walled stuff like this that looks to be a possible issue.
I think those pieces are the top off a collapsible camping table.
Could be Dean. There were some round tubes that looked like they may have been the base. Cheers Rob
Before you haul that off to the recycle center, have another go. This time, add 5-10% zinc. Hardens it right up. Machinability and surface finish improves dramatically. All that smeary stringy behaviour vanishes. 1% copper (in addition to the zinc) makes it even better.
I will leave metallurgy to the experts.
G'day Rob. I've melted the left over pieces of aluminium cladding and have found it gives too much dross, has a cloudy finish and when solidified has the rough finish you described. I haven't machined it and now watching you I won't bother.
Cheers Peter
Hi Peter. The rough sand paper (almost spikey) surface finish rang bells that this was unusual straight away. I was dubious even before I turned it. Ally sure has zillions of variants. I find that scrap alloy vehicle wheel rims are pretty good for this process. Cheers Rob
Rob,thanks for that info.I've been saving for casting.Going to weed out the junk.Cheers!!
Hi Patrick. Scrap ally is a mine field. The best option by far is to melt down alloy car wheel rims (all the prominent home casters go this way) or engine castings and know it will be fit for purpose. Anything else is totally suck it and see time. Cheers Rob
I think most extrusions are 600 series and that should be ok if not the best to machine.
I'm wondering if it's not just the grade but the heat treatment coming into play as well.
Sharp HSS tooling and plenty of speed with coolant might be worth a try too.
Hi Lee. The Banggood inserts work extremely well on ally, so I doubt HSS could improve on that. I use both. I can only deduce that this is really terrible ally to machine. Cheers Rob
Hey Rob, Have you tried using borax during your melts to clear out impurities added to the aluminum? I mix all sorts of aluminums when melting and usually have great results. Might be worth a shot mate.
I've tried all these supposed remedies, but basically it's a waste of time. You need good aluminium in to get good aluminium out, simple as that. The main thing you can do to get a better result is to pour as soon as it's melted and DO NOT overheat it. Cheers Rob
Hi Rob. Very interesting. I was given some off cuts of aluminium frames that are used for solar panels, also extruded. Haven't got around to melting any yet but I will keep it separate from my other cast scrap aluminium after watching this. Cheers, Alan.
Hi Alan. Pays to keep the various types separate until you understand their properties. I was a bit surprised at how badly it machined. Usually extrusions are not this bad, but rarely good. Even the BG insert failed to achieve a decent finish. Cheers Rob
Hi Alan, just a follow up on this stuff. The weird thing with it is that 90% of the dross sank to the biottom of the crucible rather than go to the top as normal. Very odd. I had a close look at the dross but couldn't see anything different about it, but obviously there was some heavier element in it than the plain aluminium. It also is definitely not anodised. I took it all to the recycle center today and got enough for a bottle of 1698 ;) You may be OK with that ally extrusion you have if it is thick enough that it can be drilled and tapped for fabrication, that sounds hopeful, but sample a bit first. Good luck. Cheers Rob
@@Xynudu Hi Rob. That is strange, the dross sinking to the bottom. Converting aluminium scrap into 1698 is a great result 🍺👍👍 The extrusion I have was free so it's no great loss if it won't cast, I can always find another use for it. Cheers, Alan.
Try to add 3-7% copper...
Thanks Rob👍
Illuminating
I wonder if you added some copper to it if it might work.
Maybe. Copper has a much higher melting point than aluminium though.
I thought that too. I guess you would need to melt the copper first and then add the aluminium. Luckygen might be able to answer that 🙂
Thanks for the tip!
Hello Rob,
Interesting video, thank you... I was wondering if you mixed some cast and extruded aluminum together would you get something that is useable?
Take care.
Paul,,
Hi Paul, It would improve it, but you would still have B grade ally. Better to use the good stuff and send the crap to the recycle center for some money. I did that today and got enough money for a bottle of Shepherd Neane 1698. Now I think that's a much better outcome ;) Cheers Rob
Hi Rob, what do you reckon of beer cans for an aluminium source?
I don't drink anything out of cans, so I've never tried melting them. I see people melt them on YT, but rarely see the result if they machine the ingot. Cheers Rob
G'day Rob/Ozyrob. I've melted near 500 cans, son in law provided, the aluminium machined well but the melting process was onerous. Even squashed the cans are bulky with very little product so it takes a lot of time and you loose probably 20% if not more to dross. I have found automotive castings and mags a good supply.
Cheers Peter
@@Xynudu Hey Rob, havent you heaard? Tinnies are back in vogue ;)
I doubt I will ever be in line with whatever is in vogue ;) LOL. I think I live on a separate planet. Cheers Rob
Hi Peter, I've found that anything with a lot of surface area makes lots of dross. So I'm not surprised. I never bother melting machinings for the same reason. I'm with you on the alloy wheel rims and also Myfordboy is a big fan of them.
Cheers Rob
I'd rather say choose thicker material than by cast or extruded, since it all starts out cast, certain alloys are good for extruding or don't work out well as cast in a DIY setting. aeration and small batches can give variable results and make you pull your hair out haha
Interesting topic Rob, hopefully this helps a few home casting people out. Have you ever tried Al cans, I can't imagine they are up to much but could be wrong. Cheers, Jon
Hi Jon. I've never tried drink cans but plenty of people have. I don't know how well it machines up. Cheers Rob
Aluminium drunks cans are very poor stock for melting. Firstly they aren't made from an alloy suited to casting and also they have such large external surface area to low volume of metal that excess dross and oxides become an issue.
Would it be possible to alloy it with some other metal to make it usable?
Maybe, but what to add ? Metallurgy is an exact science. Cheeers Rob
Yes It is. But when they change the grade i think they add a lot of pure aluminum too
I can't comment on that Gustavo as I'm not a metallurgist. Obviously they add particular element(s) to make it machinable /smoother when worked. Cheers Rob
@@Xynudu i would start with adding some copper.
@@Xynudu Yes, I suppose knowing what one was starting with would be necessary as well.
Cheers mate!
Hey Rob, thanks for the foundry tips. Question:
I have a large stepped cone pulley, you know like off the top of a drill press, but its quite hollow and I want to fit a bearing or two. I was thinking of melting some alloy and just pouring it in. Will this work? will it shrink and fall out? What are your thoughts?
Hi Max. I would rather machine up a steel centre for the bearings, and press or heat shrink it to fit the ally cone. Use Loctite on it as well. You can pour in molten ally and it can work, although there's no guarantee you won't have problems doing it that way. It will semi melt the pulley near the centre and fuse it all together as it cools. I did it once a long time ago, but can't remember what it was for. Good luck. Cheers Rob
@@Xynudu Just to add my 2 cents: poured aluminium will not attach/fuse to pulley. Oxide film will prevent mixing aluminium between pulley and poured aluminium. Better to machine steel/aluminium insert and press into pulley.
Hi Rob ,
Could they be anodised ? Just thinking the oxide coating could be polluting the mix .
No, definitely not Ian. I shoved one into the molten ally to see if it was coated in any way, but no sign at all, even when it partially melted off the end. It's just not machine grade. Cheers Rob
@@Xynudu
I know that when I have welded some aluminium it made it near impossible to machine - like trying to machine chewing gum ! I think it was 6061 T6 and welding it removed the hardness it think .
I wonder if adding a small amount of the extruded crap to some of the mag wheel alloy would sort it out ! Might make it useable as a filler so you don’t use as much of the good stuff in the pot .
Try to forge them, then machine It again and show us the difference :D
Thanks for sharing your test results Rob. I wonder if those extrusions are closer to pure aluminum like soda cans? My results from soda cans are a bit like what you ended up with.
I haven't tried drink cans. I always thought they would machine OK, given the ally needs to be maleable to press them out. Once again, drink cans are not machined, so that characteristic is not necessary. It all comes back to cost. Obviously the manufacturer will go with what ever grade is cheapest to do the job satisfactoraly. Cheers Rob
@@Xynudu I can remember a guy on RUclips who melted down several hundred drink cans and poured it into a big rectangular slab, then used it to mill it into the upper and lower receiver of an AR-15 semi-automatic rifle. He did the same with old rifle brass btw. So yes, drink cans should be fine to machine after its been molten & recast. More likely it has to do with the temper or how "clean" it was re-cast (i.e. making sure it takes up as little gas as possible).
I see a lot of guys on YT casting aluminium at way too high a temperature and it's no wonder the end product is full of holes and bubbles. I pour all of mine at the lowest possible temperature and get excellent results (with good ally). Brass is just the opposite and likes to be really hot to get a clean cast. They are the only two metals I've smelted and probably ever will. Cheers Rob
"absolute shit" haha that's funny as bro.
The composition of aluminium alloys is listed in Wikipedia
en.wikipedia.org/wiki/Aluminium_alloy
Only one is listed as "beverage cans" Grade 3004 97.8% aluminium, 1.2% manganese, 1% magnesium
there are so many other grades of aluminium that could be classed as "extrusion" that it is hard to see the wood from the trees.
Most castings seem to contain Silicon and magnesium (and many other metals), the ability to add silicon may be difficult due to availability (maybe some computer chips), but copper does not seem to be an important part of the mix.
A good solution to using the extruded material could be to add it to casting scrap in small quantities so as not to dilute the silicon content too much in the resultant mix.
there appears to be a different section grading cast alloys but this section does not include much about composition.
As to the comment about adding copper to the mix it can probably be dissolved in the molten aluminium like sugar in water. (the smaller pieces the better to aid dissolving)
The following PDF lists properties of machining aluminium, Heat Treating is listed, wonder if the your casting process may effects the "temper" of the material. Zinc is present in the material they test, so would not appear to be the cause of the machining issues.
Machining and Machinability of Aluminum Alloys
cdn.intechopen.com/pdfs/13408/InTech-Machining_and_machinability_of_aluminum_alloys.pdf
one final thought from someone who has never cast anything (unless you count lead fishing weights) would adding some "flux" to the molten mix get rid of the possible contamination with the anodized finish on many extruded items.
Hope this is of some help
Chris
I have done a little bit more reading about TEMPERING the casting before machining, our it will be really gummy and unstable.
It is a mine field, the general advice is IF you can't heat treat the part you should leave it up to 6 months to age or it will be dimensionally unstable after machining.
Look on the internet for heat treating aluminium to grade T6, it involves several hours in an oven at 700+ degrees (F I think) and then quenching followed by more hours at 350 degrees (F I think) to "age" the material.
That is if you have an oven 😂😂.