pcm81 Posted March 1, 2015 Posted March 1, 2015 Hello all.Total newb to ball milling here. I am interested in creating some very fine aluminum and iron oxide powders for small scale thermite welding. As the result of this hobby i also want to see just how fine of a powder i can make. I read that to get powders of size D balls no larger thn 1000xD should be used. I intend to use #12 (~1mm) leadshot as my grinding media. My questions is this: Do i need to harden the leadshot or will it work as is? I do not want to contaminate the final powder and I intend to use #240 sieve to separate powder from lead shot. Thanks ahead.
Jakenbake Posted March 1, 2015 Posted March 1, 2015 If you are that set on milling metals I would suggest using steel balls. Milling metals will wear out even hardened lead media in no time. I hope you have done your research on the dangers of milling pyrophoric metals. On another note if you do choose the steel balls remember to never mill a "live" composition like BP. Only mill fuels with it or oxidizers never both at the same time.
pcm81 Posted March 1, 2015 Author Posted March 1, 2015 (edited) If you are that set on milling metals I would suggest using steel balls. Milling metals will wear out even hardened lead media in no time. I hope you have done your research on the dangers of milling pyrophoric metals. On another note if you do choose the steel balls remember to never mill a "live" composition like BP. Only mill fuels with it or oxidizers never both at the same time.I have no intention of milling live mixtures; I chose lead for the safety reasons associated with milling reducing agents like aluminum and magnesium (steel or iron can spark). Lead and ceramic seem to be a safer choice with lead being heavier, hence having stronger impact forces. Also i could not find a 1mm sized ceramic media. Is there a better choice than #12 lead shot for this application? I am also thinking of just using 60 grit SiC abrasive, however i am worried about cross contamination as the result of SiC breaking down to sub 230 grit particles and passing through my sieve. Edit: I should add that the feed material will be close to 200 or finer grit. Edited March 1, 2015 by pcm81
Jakenbake Posted March 1, 2015 Posted March 1, 2015 (edited) What size of mill are you planning to do all this with? You could always add around antimony to the lead and recast it followed by water quenching. Maybe an option if you have access to a shot tower. Edited March 1, 2015 by Jakenbake
pcm81 Posted March 1, 2015 Author Posted March 1, 2015 What size of mill are you planning to do all this with? You could always add around antimony to the lead and recast it followed by water quenching. Maybe an option if you have access to a shot tower.I got the cheapie 6lb ballmill off amazon; its similar to what HF sells. I am not going for huge quantities so if needed i can speed it up via duck tape on drive shaft and reduce load proportionally. I have a mini furnace (goes up to 2200F) but no casting molds or experience; hence i figured i'll go with #12 shotgun shot load, it is about 1mm lead BBs. I don't think i have the tools to cast my own shot, but i can melt lead; but dropping it in water as small drops to cast my own shot would be the trickiest part.
Jakenbake Posted March 1, 2015 Posted March 1, 2015 In my opinion you are going to need a much larger mill with a lot of media to get a particle size smaller than what you have already. Casting molds can be had on Amazon along with smelting pots. But to get the particle size you are after you need smaller media than what is easily cast. That is where the benefit of the shot tower would come in.
pcm81 Posted March 1, 2015 Author Posted March 1, 2015 I was actually considering taking some large grit, say grit 30, SiC abrasive, Sieving it, to make sure all the small stuff is cleaned off and then tumbling Al, Mg and Iron Oxide in SiC grit. But i worry that SiC will chip and produce SiC particles that will sieve through my 240# sieve.
MrB Posted March 2, 2015 Posted March 2, 2015 Your not going to mill aluminum or iron oxide with lead media. Period. You will be polishing of lead onto your harder stuff, in this case, the aluminum and iron oxide.You also need a fair bit larger then 1 mm shot from a shotgun cartridge. That size wont mill anything. It would make for a great polishing compound if combined with some soapy water... Get real media. For metals, use ceramic media if you can afford to replenish it every now and then. The metals will wear it down. Otherways, use stainless steel balls. Preferably none sparking ones. Your main problem with milling this stuff isn't going to be sparking, or not sparking media, but when you go to open the jar, and let in oxygen. Hence "preferably" none sparkling ones. If they spark, the stuff might melt it self through what ever it's sitting on, but it shouldn't explode. Well, at least not untill it melts through the jar anyway... It may very well explode, or strictly speaking, deflagrate, when you open the darn jar, no sparks included. Good luck.B!
pcm81 Posted March 2, 2015 Author Posted March 2, 2015 Your not going to mill aluminum or iron oxide with lead media. Period. You will be polishing of lead onto your harder stuff, in this case, the aluminum and iron oxide.You also need a fair bit larger then 1 mm shot from a shotgun cartridge. That size wont mill anything. It would make for a great polishing compound if combined with some soapy water... Get real media. For metals, use ceramic media if you can afford to replenish it every now and then. The metals will wear it down. Otherways, use stainless steel balls. Preferably none sparking ones. Your main problem with milling this stuff isn't going to be sparking, or not sparking media, but when you go to open the jar, and let in oxygen. Hence "preferably" none sparkling ones. If they spark, the stuff might melt it self through what ever it's sitting on, but it shouldn't explode. Well, at least not untill it melts through the jar anyway... It may very well explode, or strictly speaking, deflagrate, when you open the darn jar, no sparks included. Good luck.B!I bought some 10mm and 20mm ceramic media, and intend to use it for larger starting size (shavings or a mixer output). What i was concerned with is the media choice for the final stage of milling (where input grit is on the order of 60-100 micron). I read some place online that very fine particles (approaching nanometer scale here) will stick to each-other and to the grinding media faster than the media will mill them to smaller grit, once the particle sized gets to about 1/1000th of the grinding media.
MrB Posted March 2, 2015 Posted March 2, 2015 At that rate you might get away with some tiny ceramic media, or ball bearings, but i don't see lead working out to well.B!
pcm81 Posted March 2, 2015 Author Posted March 2, 2015 At that rate you might get away with some tiny ceramic media, or ball bearings, but i don't see lead working out to well.B! I think a 1 to 2 mm ceramic media would probably be ideal; however I could not find any for sale. Any one know a good place to get some? Smallest ceramic i saw was around 1cm in size.
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