I recently looked up some prices for round bearing bronze and wow is it expensive. I occasionally have access to some bearing bronze that is left over from turnings. Would it be practical to melt it down and cast it into slugs? How difficult is it to avoid it being too porous to use? I have never cast anything before except for silver.
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Question about casting bronze
- Thread starter Upnorth
- Start date
TorontoBuilder
Sapientia et Doctrina Stabilitas
My understanding is that bearing bronze is sintered in order to have that porous character.
Melting it would eliminate that character. I stand to be corrected tho
I don't think all bronze is sintered. This bearing will be in a chamber with lots of oil so I don't think it would need to be self oiling like a sintered bearing is.
Best for casting imo, and that many other enthusiasts, is 873 silicon bronze. It has zero or close to zero zinc, and casts and machines well enough. No/low zinc is important as it boils off before the metal is at casting temps.....that is why brass is challenging to cast. The way to overcome that is a very intense furnace that quite quickly raises the temp so not all the zinc is burned off, something I don't have so i try and stay away from stuff with zinc. If you do melt something with zinc, have things well ventilated .....you can see steady white wisps of it coming out of the melter - not good to breath and of course the more of it you lose, the crappy will be alloy you are left with and casting thereof.
Get an ingot from Sculpture supply, best way to go imo if you want a quality result. I've got a nub of one and when it runs out will buy an ingot. Several hundred dollars for 20 lbs, but with that much, I'll have a lifetime supply (I've only used it for small stuff)
If you are just trying to recycle, as I understand it, that can be very challenging to do from chips, but no first hand experience. When I've cast bronze it's such a challenge getting everything right, it's a big win being able to eliminate sources of error where ever you can, e.g. using a quality ingot of the right alloy. Started using mystry bronze from the bin, not worth it - there is lots time and energy spent on each pour,
sculpturesupply.com
Get an ingot from Sculpture supply, best way to go imo if you want a quality result. I've got a nub of one and when it runs out will buy an ingot. Several hundred dollars for 20 lbs, but with that much, I'll have a lifetime supply (I've only used it for small stuff)
If you are just trying to recycle, as I understand it, that can be very challenging to do from chips, but no first hand experience. When I've cast bronze it's such a challenge getting everything right, it's a big win being able to eliminate sources of error where ever you can, e.g. using a quality ingot of the right alloy. Started using mystry bronze from the bin, not worth it - there is lots time and energy spent on each pour,
Silicon Bronze Ingot (Everdur C873)
Silicon Bronze (Everdur C873) is a non-ferrous alloy suitable for casting into ceramic shell/investment molds for lost wax casting. It may also be cast into sand molds for the sand casting process. Sold by the ingot, priced by the pound.Minimum order is one ingot.Orders will be processed based...
sculpturesupply.com
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IMO it would be cheaper to buy premade bronze bushing of common size and machine it, if needed, to your exact dimensions. Time and money spent into making furnace/burner and then finessing mold and model is not justified unless you need something really special.
I occasionally making some aluminum castings - rather simple, It works OK. Once tried to make brass thingy and it was quite bad experience.
I occasionally making some aluminum castings - rather simple, It works OK. Once tried to make brass thingy and it was quite bad experience.
The ingot idea is a good one if starting from scratch. I was hoping to use the recovered chips because the last time my friend did a particular job he had several buckets of chips from turning bearing bronze. I can get used bushings from work. They are made from a high quality bronze. I looked it up once but have forgotten exactly what type it is. It is slightly magnetic which threw me off. Some googling determined that some bronze does have some iron in it.Best for casting imo, and that many other enthusiasts, is 873 silicon bronze. It has zero or close to zero zinc, and casts and machines well enough. No/low zinc is important as it boils off before the metal is at casting temps.....that is why brass is challenging to cast. The way to overcome that is a very intense furnace that quite quickly raises the temp so not all the zinc is burned off, something I don't have so i try and stay away from stuff with zinc. If you do melt something with zinc, have things well ventilated .....you can see steady white wisps of it coming out of the melter - not good to breath and of course the more of it you lose, the crappy will be alloy you are left with and casting thereof.
Get an ingot from Sculpture supply, best way to go imo if you want a quality result. I've got a nub of one and when it runs out will buy an ingot. Several hundred dollars for 20 lbs, but with that much, I'll have a lifetime supply (I've only used it for small stuff)
If you are just trying to recycle, as I understand it, that can be very challenging to do from chips, but no first hand experience. When I've cast bronze it's such a challenge getting everything right, it's a big win being able to eliminate sources of error where ever you can, e.g. using a quality ingot of the right alloy. Started using mystry bronze from the bin, not worth it - there is lots time and energy spent on each pour,
Silicon Bronze Ingot (Everdur C873)
Silicon Bronze (Everdur C873) is a non-ferrous alloy suitable for casting into ceramic shell/investment molds for lost wax casting. It may also be cast into sand molds for the sand casting process. Sold by the ingot, priced by the pound.Minimum order is one ingot.Orders will be processed based...
Unfortunately due to the odd shape of the bearing I can't as far as I know modify an existing one. I probably won't want to go so far as to make my own casting equipment. I think it's likely I can find someone in my part of Canada who can melt some metal. I'm just hoping to make a round slug so the mold would just be a piece of steel tube. The bearing is a bit under 4 inches in diameter.
All the hollow sections of brass/bronze I have were spun cast. The only oil impregnated pieces I have are called oilite and were:
made using powder metallurgy, a process that involves mixing metal powders and infusing them with oil. The result is a porous material that lubricates itself, reducing friction and wear. I guess that would be termed "sintered".
Interesting point: if you machine the bore of the bushing, it affects the porosity adversely so you need to rough it up with 240 grit emery paper to open up the pores again.
It's OK to remelt Bronze machining chips, or the bronze saw dust you get off the band saw. I've done it many times. Sure, you'll get a little more "dross" or "slag" then normal, but far from what you would get if it were aluminum. You'll recover a good 90%+ of your bronze and the results are good, with very little to no porosity. Just make sure you give it time to solidify completely before you quench in water (if that's your thing). Normalizing at >400F or around 230C for 1 hour per inch wouldn't hurt either.