Hi all, I want to pour a foam casting using iron. I built a diesel fired furnace that I believe will get to temp but I have some questions about this and the casting. I don't get to excited about things but this could be a real game changer for me if I can get a bit better. I poured the walls on the furnace with with cement that says its good for "over" 2500f so I am wondering would anything happen with the cement if I got to say 3000f? Would it just crack or could it actually break down? I am not to worried if I have to re-pour it again with a higher temp later but I am interested what would happen? I finished machining the pattern last night. The part is 16" long and about 2.5" wide so is it acceptable to pour this standing up and is there a better temperature to pour iron at? I do not have a good slurry to use and want to see if anyone has had experience using drywall mud and then applying a layer or 2 with an actual refractory cement mud as an outer layer or would drywall mud be sufficient? Thanks for any input. This part took several hours to machine and would hate to trash it.
Welcome Todd. Others with more experience can speak to the coating and casting, but as for the furnace integrity- what was the brand and type of refractory? My experience with overheating has been that the refractory will actually slump (melt) but will also crack, spall, etc. We love pictures here. Let's see your kit! Pete
I use REFCOTECs coating now but I used drywall mud for years. REFCOTEC offers one formula for non-ferrous and another for Ferrous LF casting. The differences are the latter uses higher refractory material (zirconia based I believe), and the iron formulations are more permeable because iron will vaporize the foam more rapidly and the gases need to be expelled more rapidly to avoid defects. The problem with drywall mud for iron casting is the constituents melt and/vitrify at iron temps. That said, it's been done. Here's a thread where drywall mud was used. Cast iron lost foam | The Home Foundry Here's a longer thread with lesser result and other coatings. Trying Lost Foam with Iron | The Home Foundry I don't Satanite or ceramic shell coating are not nearly permeable enough. I have some home brew coating recipes but...... Post a picture(s) of the pattern please. Make a simple pattern or two to experiment with. Use drywall mud on one and no coating on the other. Best, Kelly
Hi Kelly, Your really the reason I joined this forum. I love to see your work. Here are a couple of pics to give you an idea. I could really machine this but I wanted to give this a shot and see if it would work. The cost of steel is absolutely crazy and I some spare rotors just laying around waiting to be remelted
Thanks for the replies all, I am really excited to make this happen. I built this furnace last year and I was in a hurry, so I purchased refractory at the local Menards. I think its called Acona or something close. I think I poured it to wet as I have done a few aluminum pours in it and the walls are cracking but thats ok I can repour it some other time. I am contemplating making a mix of drywall mud and something I purchased a while back that is called heatguard. This is a powder and a higher temp coating for crack repair but I am not sure how much to put in yet. Still pretty new to this foam casting but I am lost as to why anyone would use a sand cast if this works? This seems so much easier and the cost of petrobond is crazy. I actually work for a diesel fired hydronic heater company so this worked out well for me Here are a few pics of the set up. I think the hardest thing on this was making the air divertor blades on the nozzle which I am not 100% makes a difference. Added a pic of the sprue placement. Any thoughts?
Thanks for the links BTW. If appears the best results are pouring around 2600°f? Does this sound like a feasible temp to start with? Kelly I saw a video you did with a pouring basin you made and then in one of these posts you sent you said that epoxy might work? Did I read that correctly just to try?
I'd say the chances of anything bought at a big box store being a durable foundry furnace refractory mix are remote. Pizza ovens maybe, iron duty furnace.....nope. The furnace construction looks good but if it is lower refractory material it could melt into a lump of glass in one heat at iron temps. I hope not but if so, it might be difficult to chisel out of your furnace hardware. At a 2600F metal temp you'll have at least 2900F furnace temp. All iron duty furnace hot faces are consumable.....it's just a matter of how quickly they are degraded. I'd skip the heat guard for the same reasons as above. Menards products idea of high temps and molten iron are not on the same scale. Oh, there are plenty of reasons to choose one over the other. It's a longer discussion, probably best addressed in the sticky thread in the Lost Foam subforum. Sorry, I can't tell what's going on from that picture. Need some different views. Looks like a long sprue stuck to a piece of cardboard on top of something whose features I can't make out. I think the take-away is/was nothing will be reusable for iron, so just accept they will be expendable one-use items and make them from something practical, like mold sand with binder. If you make sodium silicate cores, that would be fine, and yes, epoxy or other resin binders in the right amount, or even just tightly rammed green sand. Best, Kelly
Sorry for the bad pics. The powder is actually a pro type of refractory crack filler not a Menards’s brand. I brushed the first coat on and it seems to adhere well so I am going to give it a few more shots and see what happens unfortunately not to sure how many coats to put on. I decided to change the sprue because I am concerned with the immediate 90 after entering. I honestly don’t know enough about this right no but it looks to me like it would try to take both paths. Going try and stand it up and pour that way
I wish you well but that one may be a challenge with the relatively thin wall. Hard for me to gauge without rough dimensions. The smaller the distance from top to bottom and thicker the wall, the greater the chance of success with it gated at the top......will need very hot iron with good fluidity, but most likely will freeze before bottom portion of part fills. A (very) long sprue may work against you in regard to heat loss. Will likely need a different gating approach but ya-never know. You'll also likely need to place weights on top the sand to avoid floating the sand in the mold. Iron is denser than silica sand. -Good luck. Have you ever melted iron before? Be safe, it's not child's play! Best, Kelly
No sir I have never poured anything this toasty before and that's why I'm here hopefully asking the pro's all the right questions. I have looked all over the net but there is very little about pouring iron. Tons of stuff about aluminum but not steel. All the walls on this are 1/4" thick and you have me a little worried about flow so I am going to put a 3/4" runner down the center to feed the bottom and both middle legs. I will then be feeding from both the top and bottom up if all goes well. I will cut them off if it works. This is a part that is not in existence and I need badly. I was actually going to pour a big block of steal for this to begin with and I could just machine this part but then I realized my crucible wasn't large enough and a #40 crucible is a pretty large cost plus kinda hard to get so this is why I am in the hole I am in. I have wanted to try iron for a while but had no intentions of starting on a piece this complicated but this is the quest the lord gave me so I will work with it and hope for the best. Honestly not to concerned except for the furnace melting down and I just do not see this happening if the crete is good for over 2500f. I totally agree with you on purchasing box store refractory garb but I did not want to spend $100 a bag at the time although in hind site I probably should have. Just finished the last or hopefully the last coat of mud on the part and I will cut a new gate in the morning. I will probably put a small coat on it to see a comparison and then fire in the hole!! Say a prayer for me pls so I don't cook off my toes Do you know if melting 4140 chips into blocks is attainable with a set up like I have? Thanks for all your replies!!
Wow, there's a lot to unpack from that post. Please don't take it the wrong way, because I do want to be helpful, but asking for help, having already made a furnace, a foam pattern, gating, coating, and expecting to get a part first time pouring iron, and not injure yourself, well that may indeed require some divine intervention. All of the following comes from a guy (me) who showed up 10 years ago with that A60 in the left of my Avatar, ready to make 60lbs pours right out of the gate. The experienced members of the forum told me I was going to kill myself and should start smaller......and I was just pouring aluminum, and still am in all my videos. I listened to them. Iron is >2x the temps. Although there are some pros here, most are hobbyists. That doesn't mean they aren't knowledgeable, many are; very much so. But it does mean they know how to safely manage in a hobby environment without access to all the things available to pros. Even so, there are not many active iron casters here.....there's a reason for that. First thing you need to do is search the difference between iron and steel. Although you may eventually succeed in melting iron, and may even get some steel to dissolve in your molten iron, you won't be melting and pouring steel from your fuel fired hobby furnace. There is a wide range of melting temps for iron. Do you have and are you familiar with Ferrosilicon (FeSi) and it's use in iron casting? If not read up. I don't know the purpose of your part but if you intend to machine it in any way after it is cast you'll want to understand what achieving grey vs white iron means. You mentioned an #40 crucible. Do you really mean that? Because using an A40 for your first iron pour would be insane, and looking at your part, certainly isn't needed for a part of that size. What crucible size are you using? It sounds like you have used your burner for other lower temp melts. It will need to be in a fine state of tune to melt iron. I suspect you'll have some learning to do in this regard just to get to the point where you can melt iron and properly gauge temperature. Safety: A crucible of molten iron in a furnace can be hard to look at without eye protection. The radiant heat is intense. You'll need all bare skin covered if you're within a few feet and full-face shield (preferably shaded), spats on your shoes and leather non-combustable cover. You'll need some great gloves and a shield on your shank because your hands will be close enough to the crucible that you probably won't be able to stand the intense radiant heat. Will you be pouring over earthen ground? You should avoid pouring over concrete. A significant spill can cause spalling and a steam explosion, and given all of the above, chances are much greater that you could have to abandon your pour or even have to drop it. You'll be pouring iron onto coated foam. The foam will turn to gas and need to escape. If the coating is not thoroughly dry it will turn to steam. This can become violent under the right conditions, meaning it could spit the metal back out the pouring well. When I said iron is not child's play I meant it. It deserves/demands respect. You have a lot of firsts occurring and it's why I suggested you start small. It can be done (relatively) safely but if you haven't considered all of the above, don't allow forethought and survival instinct to be replaced by faith. -Be safe! Best, Kelly
Thank you for your concern Kelly it is greatly appreciated. That’s not common today Yes 40. It would be just a square block to machine. I decided to do a test run on a smaller amount. It started melting around 25min. I was at full bore around 35 minutes and seemed like there was a ton of slag on top but liquid on lower half almost as if I plateaued and could not get it any hotter or I was so much hotter on the bottom of the crucible then the top. I pulled it around 45m in and poured out the molten metal. The top "slag area" measured approximately 2500-2600°ish. I need to lengthen my probe and find something to skim with. I just can’t get over all the slag if that is what it was. That’s a lot of waist. Is this expected with older iron rotors?
The fact that you are achieving liquid iron in relatively short time is encouraging. What are you measuring temperature with? Slag is normal. Depends upon what you mean by "A Ton". What's your yield? How many pounds of iron out versus iron in? Hopefully you'll get some input from the Fe guys here. You mentioned not finding a whole lot on YT. You might try: luckygen1001 - YouTube He is also known as Ironsides and is a member here. Best, Kelly
