Filtering molten cast iron.

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100model

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Here is a subject that is never covered on youtube, using filters with molten metal. In my video I used a filter with cast iron but these filters can be used with any metal such as brass which can be a dirty metal to pour.
 

Zeb

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Very interesting and thanks for sharing. I read about it in the US Navy foundry manual, but I always wondered what it looked like.

For those that have it, you can reference pg.141 Speed of Pouring and Figs. 194-195.
 

GreenTwin

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I think those Navy Manual Figures use more like a core material with straight holes in it, rather than the ceramic foam, but the idea is the same.

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GreenTwin

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I tried a ceramic sponge filter several years ago, and while the seller assured me that it would easily pass iron, it did not.

The problem was that at the time, I did not know how to correctly tune an oil burner, and so my iron was not hot enough to pass through a filter.

I was really surprised that 100model's filter passed the iron with such a slow pour rate, so that speaks volumes about how good his pour temeratures are.

The filters I have seen in commercial use typically have a sprue that is about the same diameter as the filter, which perhaps 2.5" diameter, and generally round.

The filter appears to also function as a velocity control, and the parts in the flask can be radial around the large spure, with no runners at all.
So you just pour the sprue full as fast as possible, and hold it full.
A slow pour is generally going to clog the filter I think, or has the potential to clog the filter.

The gates could be oversized if the filter is acting as a velocity controller.

Filters are used extensively in commercial foundries, but they have induction melters, and can easily add quite a bit of superheat to the iron.

I think with an oil burner, about the best maximum pour temperature that can be reached is in the 2,500 F range, perhaps 2,600 F, but that is a guess judging from what others have said.

Here are the sponges I purchased, and the spue that I used the filter with.

The last photo was from another pour with a filter, that also came up short.
At the time, I was pretty clueless about foundry work, and just blindly stumbling through the casting process.

I think I could use filters now successfully, but I use spin traps at the end of the runners, and they work as well as a filter, and don't clog if the pour temperature is on the low side.

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GreenTwin

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That is a nice crankshaft pattern, and just begs to be poured in ductile iron.

Has anyone every poured anything in magnesium?

Could a nickle-mag alloy be melted without it bursting into flames?

I have desulfuring material, and would like to pour some ductile iron crankshafts.


Pat J
 

GreenTwin

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And I get the "you should never pour over concrete" thing all the time.
It is always from those who have never poured iron in the backyard, or so it would seem.

I have spilled a lot of molten metal onto my concrete driveway, including aluminum, brass/bronze, and iron.

I don't recommend anyone pouring molten metal onto concrete, since it may explode.

I can say from experience though that spilling molten metal onto my concrete driveway has never caused an explosion.
My driveway needs to be replaced anyway, which is why I don't worry about spills on it.

The thing I fear the most is spilling molten meltal onto anything that has moisture in it, and I have had violent explosions from that.
That is why I never pour over sand, because the sand will always have moisture in it.

The sand I use for molds is a commercial sand that is apparently baked, and has an extremely low moisture content, which is why my molds don't explode when I pour them.

People border on hysterics when they see someone in a video pouring over concrete.
Its the most persistent myth that I have ever seen with foundry work.

If you don't want to pour over concrete, then more power to you.
If you do pour over concrete, and spill molten metal onto the concrete, you may spald your concrete, and damage it, but you are not going to get some cataclysmic explosion that will leave a huge crater in the ground.

Those who have never done foundry work seem to know the most about how to do it (at least in the youtube comment section anyway).

.
 
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giel

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i have seen concrete floors in all kind of foundry's... ni problem..
the sand you mentioned is kiln dried.. its fired in a kiln and this alters the sand in a way that it doesn't absorb moisture..

it will ADSORB moisture ( it doesn't go in the sand but goes around it (and this dries quikly)
 

abby

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Spilling molten metal onto concrete may not cause an explosion , but any moisture will immediately turn to steam and this can hurl blobs of hot metal several feet in all directions, they can cause irritating burns if they find a way into your boots or gloves etc.
 

Zeb

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I think those Navy Manual Figures use more like a core material with straight holes in it, rather than the ceramic foam, but the idea is the same.
Nice, I was hoping someone experienced would chime in on the book's mention of it.

As for concrete and stuff, it's good for me the beginner to read about pros and cons. When it comes to oxyacetylene, I weld in shorts and tshirt over linoleum. Those hot little beads roll right off the skin when the oxygen pops.

My first series of pours, however, will be in a space suit under supervision without any cameras rolling.
 

timo_gross

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It would be nice if some one would give me a reasonable amount of nicklemag to have a go at making ductile iron.
What is nicklemag? Google search shows some handgun, which is probably not what you want.
 

GreenTwin

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I have some of what I think is nicklemag3, which is an alloy of nickle and magnesium.

Not much of it though, and I don't have anywhere to purchase it.

It has been the most difficult foundry material I have ever tried to source.

Suppliers who sell it won't sell to the little guys.

It has to be used correctly, and the sulphur controlled with an additive.
You can't just dump it into a crucible.

.
 
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GreenTwin

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What is nicklemag? Google search shows some handgun, which is probably not what you want.
Nicklemag is an alloy of nickle and magnesium.

I am not sure of the percentages, and not sure how it is made.

I have seen some use pure magnesium in iron melts, and I consider that a potentially dangerous thing to do, as you can see from this video, where I suspect they used either pure magnesium, or an additive with a higher percentage of magnesium.
Magnesium burns with a super hot flame, and you cannot extinguish it; you just have to let it burn until it burns itself out.
Pure magnesium will burn a hole through about anything.
See 1:15.

 

100model

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I watched a youtube video the other day and it showed using filters in a vertical position instead of how I used it in a horizontal position so if you are planning to use filters they can be used in a vertical postion.
 

100model

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Those molds in cold-set or no-bake sand look very nice! Could I ask what material you're using and for a possible source? I haven't been able to find these materials in manageable quantities.
Thanks!
Todd.
I found the same thing in Australia, cannot buy in small quantities. You have to buy some of a foundry that is willing to sell some to you.
 

GreenTwin

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You can get a starter kit of resin binder if you can find a supplier who is willing to sell it to you.
Not necessarily cheap, but it can be purchased here in the US if you can find a supplier who will accept a small order.
This resin kit has been popularized by the art-iron crowd that frequently use resin-bound sand, and it is enough to bind 3,500 lbs of sand.
The sand has to be OK85 or something similar that is a kiln-dried commercial foundry sand.
The resin won't tolerate any moisture in the sand.

The foundry sales folks are basically doing you a favor by selling you a small quantity, since they can spend their time processing your tiny order, or process an order worth perhaps $100k or much more.

I have done a lot of literal begging and pleading to get folks to sell me supplies for foundries.

I found a nickle-mag supplier, and he sells it by the ton, but won't sell me any.
Can't say as I blame the sales folks; I probably would not waste my time selling nickel and dime quantities either; there is no profit in that.

.
 

littlelocos

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The foundry sales folks are basically doing you a favor by selling you a small quantity, since they can spend their time processing your tiny order, or process an order worth perhaps $100k or much more.

I have done a lot of literal begging and pleading to get folks to sell me supplies for foundries.

I found a nickle-mag supplier, and he sells it by the ton, but won't sell me any.
Can't say as I blame the sales folks; I probably would not waste my time selling nickel and dime quantities either; there is no profit in that.

.
We've found the same thing regarding purchasing supplies, etc. The foundry we use in Hanover, PA actually has the same issue even though they cast 6-days/week. They have agreements with a larger foundry and purchase from them. We mostly use C873 Everdur bronze for our castings. I called an alloy supplier near York, PA. Their minimum is by the ton at $10/lb, but they'd be happy to deliver. ;-)
Thanks again for the response.
Todd.
 

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