Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
Electric stove for metal casting?
my lifelong struggle to easily melt aluminium has finally been settled. the key was to just get some high quality insulation and use what ive always
had at hand- my electric kitchen stove
i was worried to crank it all the way up to heat mark 6 and keep it there, but it doesnt seem to cause any issues what so ever, on heat mark 5 i was
getting just above 600*C reading (my heat gun overloads at 600*C)
using ceramic aluminium oxide wool i wrapped up a stainless steel cup in the wool, carefully covering the whole hotplate and after letting it stand
around for an hour i was finally relieved to find the aluminium to have melted down
as for how much you can actually melt down on a stove im willing to say really depends on how great your insulation is, of what ive seen aluminium
oxide wool is by far the best way to go, although i have also experimented with sodium silicate and sand cement, but this seems to require a lot of
heating to properly cure and it can hold more heat than aluminium wool
https://gyazo.com/c1297361c81e085c9cdc41c649779e07
this takes kitchen chemistry to a new level and now low melting alloys are actually doable to mess around with without thinking about the weather
outside, and i succeeded by simply wrapping the aluminium wool around the hotplate and the cup
i might be the first melting aluminium on a hotplate- the only results im finding online is people asking and people commenting that its impossible
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
I did notice that aluminum foil melted when pressed against the heating coils of my stovetop, but I never thought to scale it up... Keep us posted!
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
Herr Haber
International Hazard
Posts: 1236
Registered: 29-1-2016
Member Is Offline
Mood: No Mood
|
|
Is there a point besides proving it can be done on a kitchen stove ?
Dont misunderstand me, I like the idea of proving it can be done in a regular kitchen with just some insulation. One hour is not bad. How much
material did you melt ?
You can find micro wave oven inserts that allow you to melt up to copper and silver. That's even higher melting and would allow you a broader range of
experiments.
This means a few purchases such as crucibles but reduces the problems that may arise with whatever you are melting and steel.
I did have quite a laugh some months ago in my kitchen looking for a hot plate mitten. Who has 2 pairs of welding / high temperature insulated gloves
in their kitchen ? 
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
|
|
|
Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
i melted down 120g of aluminium, but if the insulation is proper, then the amount wont really matter, when you can get some aluminium molten the rest
comes very easily, only issue is if you scale it up you need to insulate larger area, it will contain more energy and radiate more heat
i scrapped a large heating element from an industrial air heater, removing the fan gets you a nice crucible heating element- now if i combine hotplate
with that thing its gonna be some serious power
as for time to melt 120g aluminium, i really just forgot about my hotplate and i was slowly moving one heat setting up at a time, so it was already at
like 600*C before i went to heat mark 6- could be just 10 minutes from cranking it up
i think rockwool isolation might work as well, went to autoparts shop today to get some muffler wool, but it doesnt appear to be nearly as dense or
heat resistant as the chinese calcium silicate wool (doesnt seem to be aluminium oxide wool after all) but i think ill attempt to weld a top plate
onto my heating element, stuff the walls of the heating element with rock wool and maybe some sodium silicate/sand mixture
also one really funny thing i noticed, my first run i tried to melt down recycled aluminium foil, i had squashed the foil in a metal tube with a
hammer and a piece of cylindrical steel into a thick coin, about 10mm
i loaded a handful of these into my crucible and it just wouldnt melt
so i took one out and blasted with butane torch until glowing bright white- damn thing wouldnt melt, the aluminium oxide composite with aluminium kept
it from coalescing, when pressed against hotplate i could see some of the aluminium was squeezing out, so if you want to make a very easy heating
element for lab equipment, you could ram a large amount of aluminium foil and then carefully hammer "carve" the last bit to fit your flask, this
should resist more than 1000*C by what ive seen
as for welding gloves, mainly welding flux core and some very thick steel i rarely use anything else but skintight gloves, the thin ones with
rubberized fingertips, it will easily take 100*C off to the touch and as a bonus if you need to get some lab equipment apart they usually do the
trick, superB for handling hot lab equipment, i doubt anything coming out of an regular oven could do much harm to those gloves
my newfound desire to melt metal at home is mostly that ive had 7 zinc bars stolen from my storage - thieves these days dont know what silver looks
like, but its very neat to have the capacity to cast aluminium while dicing up some onions
|
|
|
zed
International Hazard
Posts: 2284
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline
Mood: Semi-repentant Sith Lord
|
|
Interesting that you did that. I recently used my stove top, to heat a 10 pound Cast Iron Weight disk.
To hold the heat in, I just inverted a cast iron frying pan over it. I was shooting to heat it red hot, to anneal it. It was too damned hard and
tough, to drill and tap.
Well, on my stove, it blew out the stove element. Molten metal squirted out of it. Moreover, installing a new element didn't fix the stove, the
controller also needed to be replaced.
Not terribly expensive as experiments go, but in the future I'll improvise a furnace that I don't need to use, to fry my flap-jacks.
|
|
|
wg48temp9
National Hazard
Posts: 786
Registered: 30-12-2018
Location: not so United Kingdom
Member Is Offline
|
|
The metal tube mineral insulated elements are designed to work with a relatively cool pan compared to the melting point of aluminium or the anneal
temperature of cast iron. Typically such elements are rated at about 600C. Go much above that temperature and the life expectancy drops dramatically.
I have tried to drill cast iron but its surface was very hard. I used a tungsten carbide spear point drill but it cracked before I got through. A
plasma cutter works great on plate if you don't mind the irregular hole it produces. I have an 8in disc to cut out of an old piano frame. After I
have cut it out I will try that annealing by putting it in a wood fire and letting it cool slowly in the hot ash. Hopefully I will be able to drill
and tap it with HS tools.
Apparently on thin or small cast iron parts that cooled quickly after they were cast are very hard and brittle due to the carbon content in cast iron.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
|
|
|
zed
International Hazard
Posts: 2284
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline
Mood: Semi-repentant Sith Lord
|
|
Well, my weight plates were very hard indeed. At least, parts of them. I was crafting ring stands. I was able to drill and tap holes, in some
plates, but not consistantly.
I must imagine the plates were quenched, while still quite hot. The cast iron being in some places, converted to carbon steel. High speed steel,
would not drill it properly, even with constant re-sharpening.
If the cast iron was produced from scrap metal, who knows what the alloy might actually be?
It's much tougher than expected.
|
|
|
Junk_Enginerd
Hazard to Others
Posts: 251
Registered: 26-5-2019
Location: Sweden
Member Is Offline
|
|
Cast iron is more carbon steel than carbon steel is. It will quench harden even with extremely slow cooling rates. An annealing on the timescale of
days is required to soften it.
OP: You don't need fancy insulation for aluminum. I do a lot of diy metal casting. Just use ordinary wall insulation, the rockwool or glass fiber
kind. It will keep most of its important properties up to 800°C or so. It does lose some structural properties in the 300°C range due to some
polymerish binders being destroyed, but that just makes it a bit fragile and doesnt affect it as long as you don't try to rearrange it. The first
heating will stink a little because of this(and most probably isn't healthy) so that's best suited to do outside, but it also only needs to be done
once.
That said, I gave up on electric heating a long time ago. You just can't get enough power to do anything meaningful in an acceptable amount of time. I
use a dead simple air/liquid sprayer and use diesel for my heating needs. I've estimated it to be about 100 kW. I'll melt a kg or two in less than 3
minutes even without any insulation. 
[Edited on 23-10-2020 by Junk_Enginerd]
|
|
|
wg48temp9
National Hazard
Posts: 786
Registered: 30-12-2018
Location: not so United Kingdom
Member Is Offline
|
|
Junk_Enginerd (previous post) had me worried that to anneal cast iron would require a soak of days.
See https://www.model-engineer.co.uk/forums/postings.asp?th=9097...
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
|
|
|
Mateo_swe
National Hazard
Posts: 548
Registered: 24-8-2019
Location: Within EU
Member Is Offline
|
|
I want to be able to melt some aluminium, copper and maybe gold.
I have decided to make a DIY electric furnace as its quite cheap and relatively easy.
Im going to drive it with FeCrAl heating coils and i have bought a box of high temp bricks to make the furnace.
Its not a prioritized project but is nice to work such things during winter evenings.
I saw someone on Youtube that built an oven with high temp bricks and a stove element.
It didnt say anything about how long the heating element did work before failing though.
Regarding insulation there is these ceramic "blankets" one can find on ebay that is used to insulate ovens, furnaces and things like that.
They can be found in some different thickness.
I would guess those are pretty good for insulating where temps go high.
|
|
|
Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
"Molten metal squirted out of it."
thats strange, not sure what kind of stove youre running but afaik the heating elements wouldnt naturally be nichrome or something even better, which
naturally doesnt melt at below 1500*C, and steel doesnt either (well it gets soft with heat) - what kind of metal was it, any clue? the heating
elements are typically made with nichrome wire in steel tube sorrounded with aluminium oxide so they stay in place
zed, if you have access to a welding apparatus you could test if its hardox, its a lot harder than carbon steel despite being around 4% alloying
elements, you can weld some carbon steel to it, if the weld later on cracks i'd call it likely hardox, not an expert of welding the wrong alloys but
thats how it works when you put carbon steel to hardox
also, for annealing you wanna place the heated material in sand, this greatly insulates and keeps the steel hot for longer, better results
also, i believe its up to 600*C you will get annealing benifits, while some hardening can be lost already at 200*C
to check if its higher carbon steel, hold an angle grinder to it, the more sparks the higher the carbon content- generally
yes mateo_swe, theyre great but if you wanna make the whole deal solid you wanna go ahead and get some sodium silicate, mix that with sand so it gets
damp, use this as cement, this is basically what furnace cement is made of, it holds up very well to heat and doesnt let much through, and you will
never get it off something you let it dry up on, turns into glass
i did play around with calcium silicate but with copious experimentation it seemed that ... was it 60% sand 40% sodium silicate solution was what
worked best and easiest, using other compositions just gave me brittle results
one very interesting thing ive seen was first shown by youtuber "AvE" where he heats up toast bread in a sealed metal container with argon, the
pyrolyzed product is some type of carbon thats super insulating, though very brittle, if we could find a way to crush this up and use as some type of
granulate, maybe carefully stir that up with sodium silicate or soak up some sodium silicate solution with an excess of this carbon like powder? it
has great potential.
|
|
|
elementcollector1
International Hazard
Posts: 2684
Registered: 28-12-2011
Location: The Known Universe
Member Is Offline
Mood: Molten
|
|
Quote: Originally posted by Antiswat  |
one very interesting thing ive seen was first shown by youtuber "AvE" where he heats up toast bread in a sealed metal container with argon, the
pyrolyzed product is some type of carbon thats super insulating, though very brittle, if we could find a way to crush this up and use as some type of
granulate, maybe carefully stir that up with sodium silicate or soak up some sodium silicate solution with an excess of this carbon like powder? it
has great potential.
|
It does, but only really works in a vacuum - much like a graphite crucible, exposure to air burns carbon foam away over time.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
|
|
|
metalresearcher
National Hazard
Posts: 759
Registered: 7-9-2010
Member Is Offline
Mood: Reactive
|
|
| Quote: Originally posted by Junk_Enginerd | Cast iron is more carbon steel than carbon steel is. It will quench harden even with extremely slow cooling rates. An annealing on the timescale of
days is required to soften it.
OP: You don't need fancy insulation for aluminum. I do a lot of diy metal casting. Just use ordinary wall insulation, the rockwool or glass fiber
kind. It will keep most of its important properties up to 800°C or so. It does lose some structural properties in the 300°C range due to some
polymerish binders being destroyed, but that just makes it a bit fragile and doesnt affect it as long as you don't try to rearrange it. The first
heating will stink a little because of this(and most probably isn't healthy) so that's best suited to do outside, but it also only needs to be done
once.
That said, I gave up on electric heating a long time ago. You just can't get enough power to do anything meaningful in an acceptable
amount of time. I use a dead simple air/liquid sprayer and use diesel for my heating needs. I've estimated it to be about 100 kW. I'll melt a kg or
two in less than 3 minutes even without any insulation.
[Edited on 23-10-2020 by Junk_Enginerd] |
Never heard about Kanthal furnaces ? They work very well, can be DIY and Kanthal wire can easily be ordered online on ebay or Amazon. I have two such
(small) furnaces made myself. For melting aluminum it is really easy and it even melts copper as the furnace can easily reach 1200 C.
An electric stove is totally unsuitable for metal melting unless you don't go beyond 420 C (zinc).
But in the upcoming years induction furnaces will become more affordable for amateurs.
For melting metals I now mostly use gas (propane or natural gas).
|
|
|
Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
what i dont like about making your own furnace is that youre gonna be dealing with having to find something to fit the wires inside of- and the
typical response that echoes is "just buy firebricks" (and then spend long time chiseling that out properly and correctly
anyhow- i just poured my first MgAl bar melted from my kitchen stovetop, if you have a backyard or whatever sure, using propane is very doable, theres
people on youtube who made diesel burners for this purpose.
so far for this setup ive used rockwool, some glass like fibers used for insulating car exhaust silencer and calcium silicate wool, the calcium
silicate wool is no doubt the highest quality stuff you can get for the job and rings in at about 20 dollars for 24x24" piece
if youre using a hotplate you want to either have patience or maximize the insulation youre using, now im wondering.. if i made an outer shield for my
construction, wouldnt that reflect the heat, if its polished stainless or aluminium? like a thermal blanket, there are also some suits used for high
temperature like steel casters that are some kind of reflective material
if i wanted to go all fancy on metal casting i could just get me some butane and oxygen, you can get some pretty big heater heads for those things, we
got some heads that are about 50mm in diameter at my job, lighting that thing up with proper oxygen balance and no hearing protection on will leave
you deaf for a bit
another thing i really like about these already made heating elements is that you dont have to worry about shorting out because its all nicely
compacted into aluminium oxide inside the steel tubes, so it will stay in place- however my build is to have a round heating element with a tube that
came with the heater around it, then insulation between the sorrounding steel plate, and ceramic wool on top/bottom- but it seems that the heating
element gave up after being heated up throughly, which is very sad, when i first turned it on the heating element got redhot within 5 minutes or so,
and because the coil would sorround by crucible it would translate into very high efficiency compared to just heated from the bottom and up
my first run was melting down about 175g Al and 175g Mg, i first melted the aluminium (took maybe 3 hours or so to heat up properly, 5mm thick steel
crucible) and then dunked in the Mg rods, 30 minutes later it was ready to pour, the resulting bar came out with 9 grammes deviation to my
calculations (250g per bar mold)
so, i chucked in 300g more aluminium and 23 minutes later its still not molten, seems aluminium has higher heat capacity.
image of the kitchen metal casting setup, metal plate and pieces of steel ontop to weigh it down a bit, the top reaches about 45*C where the sides are
at 110*C- seems i need to pull out that heating element and replace with insulation instead
https://gyazo.com/6a1c3e24eeb3cd37fa4ceb4d1c6be3c5
image of the casted metal bar
https://gyazo.com/290eb1fcb13bb0b7445b1a8ce4f283d3
i added a metal plate to my stovetop just incase i would cause a spill or some other exciting event would play out, plus aluminium foil that i crimped
up around the bar mold just incase of a spill, so the metal would by no means get to run away for me
as for how the stovetop is feeling, im using the one burner that i never use, and i have previously been running it for an amount of hours when
messing around with nitrate to nitrite decomposition at almost full settings, looking into how those things are put together if it does pop its likely
from the plastic parts underneath melting apart or what not, but they seem doable to replace, not that you couldnt just use a single electrical
stovetop burner instead
now that im thinking about firebricks, i think you could make your own and "chisel" out the spacing for the wires by simply putting in some steel rods
running at 30 degree angle, but you wanna make all 4 walls at the same time, then you simply chop the whole plate with the slits in it apart into 4
equal sections and chuck it in oven at max temperature to heal up well, then you can just shave some of the top or bottom off to get the grooves to
fit next to each other for smooth transition, as with heating coils you need a spiral that it can run around in from top to bottom
|
|
|
Herr Haber
International Hazard
Posts: 1236
Registered: 29-1-2016
Member Is Offline
Mood: No Mood
|
|
Were you ever tempted by induction ?
There are decent modules out there that would cost you about as much as the insulation and bricks you are using.
I've got one that I still have to assemble.
I'm pretty sure it's a lot more energy efficient than a normal kiln with a resistance.
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
|
|
|
Fantasma4500
International Hazard
Posts: 1681
Registered: 12-12-2012
Location: Dysrope (aka europe)
Member Is Offline
Mood: dangerously practical
|
|
i think i did read up on it briefly and also came across people asking if you can use induction hotplate to melt aluminium, of what i saw people were
saying its not possible because it works on magnetic objects which aluminium is not and i know that glassplates can crack if theyre heated too much-
but glassplates arent really a must. i mean i can def get hotplates, by the tonne, some digging and i should find induction glass plate
ok so, it works on electromagnetism, but that would imply loads of electromagnetic radiation right? i would wanna massively shield that thing. is
there any way to absorb EMF waves, because aluminium would just redirect those waves
ill try to see if i can scrap an induction hotplate, but once you rip that thing apart its probably gonna be problematic with getting the right
volt/amps delivered to the device itself, but it seems very compact and like it has great potential
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
