Melting bronze, brass chips.
I have been saving bronze and brass lathe chips for a few years. I am sure that there are a few wood, steel, copper, aluminum, titanium, lead, plastic, and other assorted chips mixed in but I would say that it is 75 percent bronze and 25 percent brass. Anyway, I gave about five pounds to a friend who plans to pack then in a black iron pipe and stand it up in his wood stove. Hopefully, to melt it and produce a bar of metal to make a couple of bronze/brass hammer heads out of. Bronze/brass melts at some ware around 1050-1500 degrees F. and Aluminum is around 2000 F. He has melted aluminum before so it should ge hot enough. So, do you think this plan will work? Gary P. Hansen
I would recheck a good chart on the melting point of metals before getting hopes too high. JIM
I think you've got that backwards
Aluminum melts at around 1300F and bronze melts around 1800F
Probably what will happen is that the aluminum, brass and bronze will melt and you will end up with something like aluminum bronze with lots of slag. The zinc and tin from the brass and bronze tend to react unfavorably, so the top end of the chunk of metal in the pipe will be pretty weird, kind of like what used to be called pot metal.
Before you do the melt have him put the chips on a flat tray and burn out any coolant or oil. Hydrogen from oil, water and coolant will make the copper thicken up to a gluey mass when melted that won't pour worth a darn.
The chips will oxidise and you will have a hard scale pile of nothing.
To melt chips, you need to compact them to eliminate air.
When they are briquets, then they melt easily and you will still have some slag.
I woulddn't worry about having other chips in there, it for a hammer.
Gary, I try to pour my bronze at 2150 F. Ask your friend to put a half tablespoon of borax on top of the chips before heating. This cleans the metal, and floats to help keep the zinc in the alloy (away from the air). He will want to skim the slag just before pouring. If you are pouring hammer heads, it would be a good idea to put a riser in the mold at least as thisck as the thickest part of the head, and have it rise above the top at least an inch. Also, an iron pipe is not good for either bronze or aluminum. The iron will dissolve into the melt.
The idea was to just stand the pipe up and let the molten metal sink to the bottom of the pipe. He was going to bore a taper on the inside of the pipe so hopeful he could knock out the slug and then machine the hammer heads from the slug. I will tell him about the borax. Gary P. Hansen
I wonder if your friends project isnt fraught with safety & metallurgical hazhards, unless one has a good grasp of what one is doing, Please dont think i am a killjoy, but many years previously in the foundry trade, made me aware of the problems one can encounter
Firstly melting points-- Aluminium1200 degr. F
Brass 1800degr. F
Now by the sound of things your metal, is not too clean, you mention having a fair percentage of aluminium swarf, plastic etc & maybe steel
Some time ago i was inclined to melt bronze swarf of the lathe which was pretty clean, and pour my own bar stock, sadly i do not any longer have this facility, One of the curses of any foundryman, is getting aluminium in ones bronze or brass melt, it goes through your metal like a cancer leaving a horrible slag, It is different melting Alum bronze as obtained in ingot form with some additions of riser heads etc in the production of Alum bronze casting work, But this branch of foundrywork, is more specialised
Should you melt a mixture of bronze & brass together, (assuming clean cuttings) If one melts carefully you will end up with a form of paler bronze, still allright for general work, but no use for anything like steam fittings or high strength items
Somehow i have grave misgivings as to being able to obtain the necessary required temperatures required in a wood fired stove, my melting at home, (as distinct from industry, where we had really efficient furnaces capable of holding high temperatures) Was a furnace fired with coke oven coke from the local ironworks, and later a gas fired furnace, with a powerful blower My melting operandi, both in industry, and as a hobby, was carried out by using clay graphite crucibles, and of course one had to have the necessary lifting tongs etc, not to mention safety footwear, gloves, apron, safety face visor, helmet, leggings etc, Yes even for at home, And ,children ,&pets were kept well away, as were combustible and inflammable materials
As regards fluxes for brass & bronz, i used to place in my crucible a couple of portions of broken glass before adding my metal scrap when the crucible had been brought up to heat, and occasionally a little borax, but dont go mad using a lot of this powder, The glass used to come up through the metal, and acted as a cover flux and a cleaner, &could be skimmed off before casting
Casting into a steel mould or tube can be very dodgy, The least drop of dampness and one can have molten metal exiting out with drastic consequencies, Believe me it can fly everywhere and do some dreadful injuries I would particularly hear of your good friend pouring his metal into a properly made sand mould Sometimes one finds even with a hot tube or steel mould, the brass or bronze will boil off the steel again blowing out, due to no where for the metal gases to escape Remember this stuff is unforgiving
One has to ask is the excercise worth the effort ?
Please take my suggestions as a helpfull guide, But i am not, liable or responsible for any accidents or injury encountered, remember you are responsible for your actions with molten metal, which is hazhardous
Bronze, steel pipe and borax...
Given the recipe's above, plan on the brass ad bronze being brazed into the pipe unless you coat the pipe with soot or some other sort of release.
Definitely preheat everything to get out any oil or water, or you have the potential to shoot the metal back out of the pipe.
Just be really careful about protecting yourself.
"Safely" cast into metal molds
Rig up some firebricks so the steel mold can lay in the exhaust while the charge is melting. This works best with gas, charcoal ash will make a mess, no idea what to do if you're melting with electric. Maybe throw the mold in for a minute or two before the pour, assuming your furnace is big enough.
Originally Posted by oil mac
If you can't safely move a nearly red hot mold onto the sand, then you don't have the right gear to cast.
Red hot metal in a cold mold shrinks making it easy to remove. Red hot metal in a red hot mold, both shrink, making it somewhat harder. So you want the mold hot enough that there is no possibility of moisture/oil, but not heated all the way up to cherry red.
Do it on a sunny day. My only incident occurred on a cloudy wanna-be drizzly day where it seems the very first raindrop of the storm landed in my mold. That was most exciting but thankfully no injuries. The sound was impressive, I though a spark hit my can of starter fluid. Also moisture on the outside of a mold can be impressive like bacon sizzling, maybe a bad mold design could flip over from the steam.
Plan on it blowing up, and nothing bad will happen when it blows up, since inevitably a bird will make a bulls-eye at the worst possible time or you'll sneeze or cough. I always wondered what happens if you pour onto a housefly or even a nearly invisible gnat.
Another good way to get hurt is let the aluminum slowly dissolve the mold, until it leaks everywhere. Again, plan ahead means no problem.
A wood stove might make molten metal, but more importantly it is not designed to handle molten metal accidents...
I hope i did not dissolussion everyone with my last post guys, That was not my intention, All i am trying to do is install a most healthy respect for this damned material, One fright i got many years ago, was pouring the surplus aluminium into cast iron ingot moulds which we used to make ourselves, This was being done, as we had not any more moulds ready, the moulds were always heated with a powerfull gas torch, One one occasion we had not heated one sufficiently and the metal fel, that it did not want to dwell too long in the mould, Due to the generation of steam in the bottom The metal came up like Mount Vesuvius, hit the low roof of that part of the foundry, and gave all and sundry present a shower bath, Fortunately there were only minor burn wounds, Result, some upset & frightened bunnies !
On another occasion i picked up a skimmer to skim the dross of a large crucible of molten aluminum, Yes dear readers you got it in one ! Off all the skimmers i lifted it was not the one i had pre-heated, someone else had used that one, and left one (not intentional) that was slightly damp, When i drew it over the surface of the melt I had a million to one occurence, which i do not think one could ever re-create, The metal blew and seemed to follow the inside of the skimmer bar,right on a trajectory up the inside of my arm and gave me a sore burn.
I suppose i could go on at length I wont go into one or two really nasty accidents i have seen , Where as you can imagine happened when everyday we were handling really large ladles of the stuff And sods law took over, or someone either did something really stupid, got something wrong,or dropped their guard
The name of this game for us all is doing our own thing, having fun,Making things virtually from nothing at a low cost, Go forth and enjoy yourself folks But Remember to take care And think on the words of caution from an old "Son of Vulcan."