Cast Iron making question

========= Assuming this is not a troll....

Thin chips will tend to oxidize badly (and even burn) and may blow out the top under blast.

Unconsolidated [uncompressed] swarf also tends to produce castings harder than a w**re's heart. Good for sash and barbell weights, but not much else.

Save your self a great deal of time, money and aggrivation and get some of the Chastain and classical books on cupolas and casting.

I suggest Lindsay books -- good prices and service. see

and many more.

All of the foundry books I have purchased from Lindsay have been first rate. I used the US Navy foundry manual #20072 @ 23.95$US as a text for my foundry classes. 1/5 the price and twice as good as anything else I could find. This is more of a reference book for people who know a litte about foundry work, so start with Chastain, and some of the reprints of the older small scale techniques.

Patterns and molds are frequently more of a problem than the furnace for the home foundry. I suggest you look into using "lost-foam" for your one-offs.

see

Petrobond is the standard mold sand but cn be expensive. see

to make your own. Also consider refactory investment [not plaster] over the foam supported in oil or dry sand.

Some free advise -- As I would frequently remind my students in the foundry class -- there are never any *SMALL* accidents or

*MINOR* injuries in a foundry. Read Chastain's and the Navy manual's safety suggestions FIRST. Concrete as in garage floor or driveway may *EXPLODE* if you spill any liquid iron.

Congratulations on your furnace. What are you using for a blower? Good luck, and post some pictures of what you cast to the drop box.

Unka' George [George McDuffee]

------------------------------ Watch out w'en you'er gittin all you want. Fattenin' hogs ain't in luck.

Joel Chandler Harris (1848-1908), U.S. journalist. Uncle Remus: His Songs and His Sayings, "Plantation Proverbs" (1880).

Nice reply, nice links, F. George. Have you ever melted aluminum with a rosebud oxy-acet or oxy-propane torch ?

========== No

At the school we used a natural gas fired Mifco. I think it was a model 301. It was capable of melting malleable iron, but this took a very long time , and the melt was super hot for student use. We used mainly aluminum and zinc and a little brass. For strength we mixed our own [approximate] ZA-27 with about the same strength as cast iron. Also melt salvage copper and aluminum to make a "bronze" for decorative stuff.

I have been more of an observer around cupola operation.

I am sure propane OX would work, but would be expensive. Also you need some flux to protect the material in the crucible/ladle, and temerature control may be a challange.

Troll around on the Lindsay site. He has the Gingery plans for an electric furnace and how to make your own crucibles. For small pours this is the way to go. We used a small high temp electric heat treat oven and a small crucible with very good results.

Unka' George [George McDuffee]

------------------------------ Watch out w'en you'er gittin all you want. Fattenin' hogs ain't in luck.

Joel Chandler Harris (1848-1908), U.S. journalist. Uncle Remus: His Songs and His Sayings, "Plantation Proverbs" (1880).

Thanx. I have some of the Lindsay books and a few others on the subject. I have not found any specific references re. small quantities melted in steel pipe-type pot.

The solvent power of molten metals shouldn't be overlooked. If you prefer to work with a steel pipe type pot, it should be covered with a refractory wash. Otherwise the charge will dissolve iron and alter the structure of the alloy you'll pour. That's not to say it won't work------it will------just not as well as using good and proper equipment.

Harold

see

see

make your

Thanks for your reply. I am not a troll. Well, no, the congrats are too soon (I have not made the cupola yet, this spring is the hope). I have the book "building small Cupola furnaces" by Stewart Marshall. I'm looking on ebay at 25 lbs (multiples) of high temp refractory cement (you add 25 lbs of sand) for $22 plus shipping, is this a OK deal?). The book never indicates anything (in my reading) about what iron base material to use. Hence my question if I can use the buckets of swarf I have been saving. And what would you do to not make it Rc=65 cast iron?

Thanks

Buy your refractory from a dealer. In or near a large(ish) city ? Look under "refractory" in the phone book. Two big companies are Clayburn Refractories, and Inproheat. Lot's of others out there. Buying from the distributor means one fewer hand in your pocket, at least at the places I dealt.

If you are not in or near a big city, get a phone book for the one you are most likely to visit.

Refractories generally have a life, when not yet mixed. Better to get fresh. One less thing to worry about. Also guaruntees you don't pay postage on a 25 pound bag of driveway fill. Or at least, reduces that risk. Would you buy portland cement off Ebay? Similar water absorbtion, similar weight. Similar chances that it's screwed. And you don't find out it's buggered until you mix it with water, then it's way too late to get your money back.

Decent castable is not too expensive. You can talk with the sales guy about what is appropriate, and available. Information like they have, is golden!

Cheers Trevor Jones

Thanks

I'm in the middle of Iowa, don't know who would have the material.

What I want to know is how to use my buckets of metal turnings. As George indicated they may turn in to hard a crap cast iron. I can live with this as long as a heat treat operation can be done with my furnase.

Ideas?

This is an aspect of foundry work I had never considered . I have no plans to do any in the near future , but long term plans include pouring some aluminum for some one-off motorcycle parts .

I come here to learn . The best lesson I've gotten so far is the depth of my own ignorance .

Most people never figure that out for themselves.

Wes

Just off the top of my head. In aluminum casting thin items are not good to start the melt with, but once you have small melt going adding them in is ok, keeps the metal from oxidizing faster than it melts.

Perhaps with cast iron it is similar. Get a melt going and dump in the swarf (if you can get near it at that heat)

We'd love to have you at our casting group.

Mostly aluminum and mostly sand molds, but all aspects of casting and metalworking are welcome.

Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

My hobby pages are here: Visit the castinghobby FAQ: The member map is here:

I'm still several years away from building a cupola but... It may be that one way to use cast iron turnings as feedstock for a cupola would be to place the turnings into a soup can, heat them to 1200 C, then compress them, still in the can to sinter them into larger lumps. It is possible that a No 5 fly press (nominal 5 long ton) might be enough to do the job, failing that, a hydraulic press could be used. Obviously, a set of tools would need to be made to hold the can while it was being compressed and to do the compressing, but this needn't be anything too precise.

Mark Rand RTFM

Silicon controls the amount of free carbon (graphite) that ends up in cast iron. To increase the carbon content, avoiding white iron, one increases the silicon content. Thickness of the casting usually dictates the amount desired, or so I've concluded from extensive reading. I've yet to run my induction furnace to create my first heat due to my house building project, so I can't speak from experience.

The other factor is how quickly your casting cools. Thin cross sections chill easier than do heavy cross sections. All that is required to achieve a level of heat treat in any iron casting is to chill it quickly.

Harold

I machine a lot of castings and I'm in and out of the foundry all the time. They do a lot of steel, stainless steel,gray cast and chromeiron. They use electric furnaces and do not want the chips even the 316 stainless chips.

As far as making hard cast iron, this is because of the lack of heat treating the casting. We machine the stuff in both the soft (350-400 bhn) and in the full hard condition (650-750 bhn). the silicon and the carbon will form nodules of silicon carbide and make the stuff almost impossible to cut. Proper annealilng will remove most of the silicon carbide and leave graphite or free carbon.

If I were to get into casting, I would look to build an electric furnace because of the versitility of that system. I would forget about doing cast iron and do cast steel which seems much easier in a number of ways, including machining after casting.

John

I've been helped by those kind enough to share their knowledge ...

Sandcasting aluminum is where I was going . I still have a nameplate that I cast when I was in 9th grade . There is an art to packing the sand ...

I shall be happy to join your group and lurk in the shadows . Another source of knowledge , right on !

Harold,

Is there a use for white cast iron?

Thanks,

Wes

============ White cast iron is harder than the hubs of hell, thus very good for resisting wear.

It is the same material as gray, but just cooled faster in the mold. In fact, some molds incorporate what are called "chills" [actually just chunks of metal, with a graphite or refactory wash to avoid sticking] to cause specific parts of a casting to cool quickly and thus be white for wear resistance while the remainder is gray for machining.

Because thin sections such as flanges and tabs tend to cool quicker, they also tend to be harder and more difficult to machine.

A common "problem" when just starting casting is removing the part from the mold too quickly. As production is seldom the goal in a home foundry a good rule is to let it cool over night. It can also be helpful to have a 4 or 6 inch piece of fiberglass insulation to put over the top of the mold to slow cooling. This may also help to avoid "sink" problems as the metal in the risers will stay molten longer to feed into the shrinks in the part. Even large risers because they are at the top of the mold will tend to solidify first and starve the part leanding to sinks and voids.

Unka' George [George McDuffee]

------------------------------ Watch out w'en you'er gittin all you want. Fattenin' hogs ain't in luck.

Joel Chandler Harris (1848-1908), U.S. journalist. Uncle Remus: His Songs and His Sayings, "Plantation Proverbs" (1880).