Teflon coated molds?

[Hang Fire]

I was on a slingshot forum today and one guy was using a Teflon coated ball casting mold. (made by somebody in the UK) He was saying as how the lead balls just fell out so easy.

Anyone ever heard of or tried such?

I has always heard PTFE starts going south around 500 f at constant exposure and 600 f for intermittent use? But maybe a boolit casting mold doesn't reach those temperatures?

[geargnasher]

Hope he likes undersized balls and flourine gas.

Gear

[Longwood]

Bug repellent?

[rbertalotto]

I always wondered why aluminum molds were not anodized. I've poured molten lead on a piece of anodized aluminum door frame and it simply balls up and flows off.

[williamwaco]

I always wondered why aluminum molds were not anodized. I've poured molten lead on a piece of anodized aluminum door frame and it simply balls up and flows off.

I expect that is the answer to your question.

[alfloyd]

"balls up and flows off."

So, would that be great on an aluminum mold?

Lafaun

[40Super]

Those coating would be great,except how do you get sharp corners and accurate sizes when the two surfaces repell each other so much. For round ball it may be ok. I have some teflon sheets from work under my pots for sliding my molds on, any lead that drips on it just slides off, makes it nice to keep the drops from sticking.

[geargnasher]

The seed has been planted. I have to try the anodizing now.

Gear

[Katya Mullethov]

The seed has been planted. I have to try the anodizing now.

Gear

Far be it from me to even insinuate such a thing , but I dont think you can do it .

[alfloyd]

Quote
"Far be it from me to even insinuate such a thing , but I dont think you can do it."

Gear:

The challenge has been made. :)

Good luck with it.

Lafaun

[geargnasher]

Far be it from me to even insinuate such a thing , but I dont think you can do it .

Can I anodize aluminum? Yes, no doubt there, what color would you like? Will the coating take the heat of casting without cracking to bits microscopically and rubbing off? I don't know. Can I anodize a boolit mould without ruining the pressed-in steel alignment pins? I don't know, never tried. I think a coat of high-temp calcium-soap grease will seal up any parts I don't want exposed to the acid bath, although it won't do much for appearance. All I want is the block faces and cavities done. I know the coating won't hold up to sprue plate abrasion forever, but it might help.

Anyone have tips on protecting non-removable steel parts when anodizing aluminum?

Gear

[MikeS]

Actually I believe the aluminum Maxi Ball moulds made by T/C are anodized, including the cavities. I have one in 54 caliber, and when casting them with pure lead, the boolits just jump right out of the cavities! I didn't realize that the anodizing had any effect on performance of the moulds, but thinking about it now, it must, as those are some of the best casting aluminum moulds I have!

[375RUGER]

the sulfuric acid electolyte will eat the steel inserts. If I recall correctly, you can alodine with those in but I never specify alodine, and it's been too many years. Alodine is not as tough as anodize.
Type 2 is soft anodize- you can specify color
Type 3 is hard anodize-only black that I'm aware of or that anyone around here does.
If you anodize with the inserts they will just disappear, that has been my experience, occasionally a small amount will remain. Usually you can install a new insert in it's place unless it is a real tight press fit to begin with. The best way is to just remove the insert and reinstall them after.
I'd like to know if the grease grooves fill out in an anodized/alodined mould.

[mrb7]

Can't you remove the pins and then press them back in afterward?

[geargnasher]

I'm still wondering about the grease. I'm pretty sure grease over and around the pins would seal out the acid as long as the bath didn't get too hot, but I don't know if it would protect the aluminum/steel contact points from electrolysis. Best to drive them out, I'm sure. Maybe a quick spot-heat with a propane torch on the aluminum would allow me to sneak the pins out without wallowing the holes too much.

Gear

[geargnasher]

Can't you remove the pins and then press them back in afterward?

The problem with that is they get loose if you aren't really careful, and it's difficult to stake them back into place once the holes are stretched. I'm talking two-banger Lee moulds here.

Gear

[375RUGER]

I don't think grease is really an option. Al parts get a very good degreasing bath before the procedure. Grease in the electrolyte would be like a contaminate and as close as the pins are to the cavities, it would probably migrate.

In Rangefinders sticky about mould HPing he says you can just tap the pins out with a wood dowel. I would put Loctite 609 (retaining compound) or the red stuff on it when reassembling and the pin won't be coming out, ever.

[40Super]

Ya them Lee molds are made from pretty soft aluminum to begin with. It won't take much to make the holes a little kitty-wompus. Then again maybe you'll be able to put them back in and have the cavities lined up better than from the factory, I know they don't spend much time making sure things are straight and lined up before craming the pins in.

[popper]

Hope he likes undersized balls and flourine gas. Won't need any after a good whiff of that stuff. Probably have to figure out how to peen the Al to reinsert the pins if #3 anodized. Lap the mould first as it will throw smaller.

[Bullet Caster]

This has turned out to be an interesting thread. Gear, please keep us posted on your progress. Are ya gonna Leement the moulds first? I wouldn't think that the anodized aluminum coating would be that thick. But then who knows...this is gotta be a first. BC

[40Super]

Anodizing isn't so much of a "coating" as it is a controlled oxide layer, or rust , so to speak. Then the process is stopped and the layer seals up the base metal from the atmosphere so it is protected. I think it could maybe make the bullet .0005" smaller, maybe. But, how much smaller is the repelling factor going to make the bullets??? Maybe these would need to be pressure poured to force fillout.

[geargnasher]

The thickness of the layer is controlled by the method used, and how long it's in the bath. I ordered some sulfuric acid today, my old batch hasn't been used in years and has mostly evaporated, I don't know what the concentration is anymore, plus there are dead bugs in it, lid didn't seal too well. I'll get this stuff rounded up and give it a go here in a week or two.

Gear

[popper]

Type II is up to .001, type III is over .001. Sulfuric acid process creates pores in the AlOx. Borate process doesn't make pores. I think the spre plate on the lee moulds are anodized

[Mal Paso]

If you plate both the cavity and face you will make the cavity oval. .001 added to all surfaces would make the cavity .002 out of round. Etch First? Corner rounding issues?

But the opportunity to Color Coordinate my casting bench? Irresistible!:bigsmyl2:

[Suo Gan]

The older NEI's were anodized on the faces, I think it was done before the blocks were cut...I have also owned another that was black anodized but do not remember the make, Lee anodizes their sprue plates on the 6 cavity molds they make.

[Hang Fire]

Actually I believe the aluminum Maxi Ball moulds made by T/C are anodized, including the cavities. I have one in 54 caliber, and when casting them with pure lead, the boolits just jump right out of the cavities! I didn't realize that the anodizing had any effect on performance of the moulds, but thinking about it now, it must, as those are some of the best casting aluminum moulds I have!

Very true, never even considered that aspect before, but those brown TC MB moulds sure work great for fill and release.

[StratsMan]

I can't spell annod-eyes, but I'm curious if this will cause a problem with the air vents...

[williamwaco]

Far be it from me to even insinuate such a thing , but I dont think you can do it .

Don't bet any money on that!

If ANYONE can make gold from lead, he is the guy that could do it.


.

[geargnasher]

My only reservation about this is that it will make the moulds cast slightly undersized and elliptical. The coating on the block faces will "beagle" the cavities apart by about 1.5-2 thousandths, but that will be offset by the coating in the cavities for a zero net change. The issue is across the parting line, the cavity will be reduced by that same amount. One would need an elliptical mould that was wide across the parting line to begin with for it to remain round. This would be a problem with borderline undersized moulds and those with critical bore-riding dimensions.

Gear