A thin hotface medium/low mass beer keg (drum size) furnace for melting Iron

I won't toss it, but as for the immediate future, I need some iron casting successes, since I have spent an inordinate amount of time tinkering around with things and experimenting.
Obviously many people who routinely cast iron use greensand very successfully, so I know it can be done.
I am ready to stop experimenting for now and make some quality iron engine castings.

I will come back to the greensand thing next spring and revisit it.

Keep in mind there is nothing sacrosanct about the summary I posted above.
It simply reflects my understanding of how to melt iron after exactly one controlled successful iron melt.
The folks with multiple iron melts will no doubt refine and clarify the ideas I have put forth.

I consider myself in the beginning stages of learning how to cast iron.
I have come a long way in my iron knowledge, but I know I have a long way to go too.

I consider the groupthink here far more valuable than any single idea that I may come up with.
I would love to hear any and all comments/suggestions/ideas/corrections, and feedback of any kind.

That sounds like a good idea.
I am going to try it.

That is exactly what I thought, and I guess it comes from discussions of combustion engines overheating if they run too lean.
I will have to get use to what the flame above the lid looks like in daylight, since the colors are not nearly as visible in bright light.

That is a very interesting story.
Reading the old casting journals and looking at the old equipment and engines that were cast in the 1800's and early 1900's tells me there was a certain genius going on in the foundries, and much to be learned if we can rediscover some of that information.

I found out about iron chills when I cast the first thin parts in iron, and made some "nocutium", which is that magical metal that can only be cut with a grinder or a diamond blade.
It was a "what the heck" moment when the teeth went away on the Portaband blade.

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I was chatting with ironsides today, and he mentioned how long I had been trying to melt iron.
I was also curious about that, and my long journey of learning how to melt iron, so I went back and looked at my pour log (I keep a log of all the melts I have completed), and came up with the following:

The 1st iron melt (with the old furnace) I did with an oil burner was successful, and that was in Sept. 2012, and produced a usable flywheel which I still use to this day.

My 2nd iron melt (with the old furnace) in Sept. 2013 was also successful, but my runners where too long in the mold, and so only half my parts filled. Most of the parts that filled were usable.

My 3rd iron melt (with the old furnace) was in Sept. 2014 (not sure why these melts were spaced exactly one year apart; that was not planned), and I think it would have been a success, but the lid lifter mechanism failed, and jammed the very heavy lid partially open, preventing me from pulling the crucible.

My 4th iron melt (with the old furnace) was in Oct. 2015 (that one year spacing again, go figure), and it used the dual burner arrangement and produced some very hot iron, but I did not prepare a mold, and so only cast ingots.

My 5th iron melt (with the old furnace) was also in Oct. 2015, and it produced iron that was right at the low range on pour temperature, and I used a ceramic filter, so the metal did not entirely fill the mold.
The part of the mold that did fill looked great as far as surface finish, but the melt needed to be much hotter to get through the filter.

My 6th iron melt (with the old furnace) was also in Oct. 2015, and again it was slightly too cool to completely fill the mold.
After the sixth iron pour (this was making parts for a steam engine), I changed to aluminum because I knew I did not understand the process enough to have predictable repeat melts.

My 7th (overall) iron pour (first iron pour with the new furnace) was on 8-15-18, and was the first melt with the new furnace.
It was just a trial run of the new furnace and burner, and I had no idea of the fuel flow rate or anything else, but I did get some hot iron, and made a few ingots.

And my 8th (overall) iron pour (2nd iron pour with the new furnace) was the other day on 10-02-18, and I had the fuel flow calibrated, the combustion air adjusted correctly, and most importantly understood the iron melting process.


So in summary, my very first iron pour in 2012 was successful, and even without ferrosilicon it produced a flywheel that was easily machinable.
My problem was that I did not understand the process exactly, and this included not understanding the best fuel flow rate, the optimum burner tuning, or how to charge the iron as the melt progressed.

Life got in the way of frequent iron melts for many years, and there was too much happening to try more iron pours during this period of time.
Suffice it to say there was a lot going on in my life other than backyard casting during these years.

What finally happened on the 8th iron pour that made such a big difference?
1. I learned that 2.75 gal/hr was more than sufficient to melt a #10 crucible of iron, and indeed fuel flows higher than 3 gal/hr actually seem to cool the furnace.
2. I learned how to exactly tune the burner for maximum heat (at 2.75 gal/hr) by watching it at night where I could observe how hot the furnace was getting.
3. I finally followed ironsides instructions to the letter, which were start with an initial melt, establish a pool of molten metal, and then add scrap one piece at a time, pushing each piece under the surface of the molten metal.

So knowing what I know now, it all seems rather simple, but at the time it was all very confusing, and there was no time to stop and figure it out or try more melts.
But those 3 small but extremely critical details above make the difference between pouring hot and very fluid iron which completely fills the mold, and having a partially filled mold and a failed pour.

And the $100 question as to why I did not follow item #3 to the letter sooner than I did:
1. I did not find that out until later in the game.
2. I was so confused about how to set the burner correctly, or which burner type/configuration worked better, that I pretty much overlooked all else, and just put iron into the crucible and hoped that it melted.
3. I am not that bright. I think most people would have picked it up much more quickly. Tortoise and the hare type thing; I am the tortoise, but I got there, and I am melting iron easily now.

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Just a note on increasing my green sand Southern Bentonite percentage as suggested in Ironsides video posted above by PatJ. I did add 1 percent of clay to my 100 mesh olivine sand that also has about 4% sea coal in it. This brought the clay content to 6%: I did notice increased green strength and cast a 45 pound pattern with it yesterday and had excellent results. I will standardize my green sand at 6% for a while. Maybe I should go to 7% as suggested by Ironsides.

Denis

 

I did decide to modify the entry point for my tuyere by adding some castable refractory to tighten the fit of the burner tube AND isolate the end of the burner from the swirling flame in the furnace. Previously my burner tube simply was pulled back from the tuyere entry by an inch or so. But, the opening was pretty loose so that combustion gases could circulate around the burner end. That caused the tube end to get extremely hot during melts and caused the tube end to thin and eventually break down after twenty or so melts. So, I'd cut it off and weld on new tube for the last inch or so of the burner. Not a big deal but annoying. Listening to your guys and looking at MIFCO's design encouraged me to modify the tuyere so the burner tube butted against refractory keeping the combustion products away from the tube end.

On the next melt I did just two days ago the tube end was only faintly glowing in darkness rather than being a bright pale cherry red. And the added refractory, to might surprise, seems to have stuck well to the existing refractory and is holding up well. I think I have had my last burned-out burner tube end. Yay!

Denis

 

Denis: Glad you got your burner tube problem sorted out.
I have been lucky to have avoided that problem except perhaps on a very early melt years ago, but seem to have hit every other conceivable problem in the past.

I need to trim off the bricks at the top of the furnace, and lower the upper stainless shell, so that any leaks at the lid do not impinge on the stainless shell that retains the lid refractory.

Its been a bit rainy here.

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I did another iron melt with the new furnace last night (3rd iron melt with the new furnace).
I wanted to do another test run, just to be sure I could repeat the last success.

I trimmed the bricks down about 3" around the top and lowered the upper stainless shell.
That seemed to solve the overheating of the lid stainless shell.

The melt went well, and the furnace came up to temperature pretty fast.
The iron gets quite hot, and starts that roiling motion.

I tried some calcium carbonate towards the end to see if it would help solidify the slag, and it seemed to work a little, but not really that helpful as far as congealing the slag into one mass that could be scooped out.

I could not find the vermiculite that I purchased a few years back, but I wanted to try that on the slag.
I will have to buy some more. It is available at the hardware store in the gardening department.

I also added ferrosilicon, and that helped the fluidity quite a bit.

Everything went well.
I still don't have any decent molds made.
Last night I made some more ingots.

I still have the multi-valve test stand connected, but I don't need it now since I know that to melt iron, the leaf blower runs at its lowest speed setting, and the combustion air control valve is used in the fully closed position. It is just a matter of starting the furnace with a rich mixture, let it heat for about 30 seconds, close the lid, and then fine tune the fuel needle valve for a bit of flame coming out the lid opening.

I melted some of the ingots from the previous melt, plus some scrap that Chirpy gave me that had a lot of paint on it.
The paint did not seem to create any problems. A little more slag perhaps was produced.

There is no doubt this burner/furnace arrangement can easily melt iron with respectable melt times.
I ran the burner at about 2.5 gal/hr on diesel.

The IR/UV is really intense when the furnace is opened and the crucible lifted out.
I think I am going to buy a No.5 shield for my faceshield.
I need more protection from the UV/IR.
It is really something to behold at night when the furnace is opened.


















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What is a doghook?
Have I seen that?
I think I know what you are talking about.
That would be a resin or sodium silicate mold for sure.

 

I did an iron pour demonstration for some of the Metal Museum folks tonight (4th iron pour with the new furnace).
I did not have time to make any molds (its been a very busy week), so I did a splatter-fest sort of pour, with the crucible held up high to enhance the effect.
The groove in the ground was pretty wet from a rain earlier in the day and that also added to the splatter.

One day I will get caught up with things and make some molds, so I can get some parts made.
Tonight I melted ingots that I previously cast, so I did not really waste any metal with this pour, and can reuse whatever went into the trench.

The furnace and burner worked well, and I continue to be impressed with the speed of the melt and the temperature that the iron can reach in an hour.

And it was great to converse with people (Metal Museum folks) who have done cupolette iron pours for many years.

 

The furnace interior has a nice bright glow to it, now all you need are some termite mounds to pour it into.

 

I paid attention to how bright the furnace and crucible were when the furnace is open during the previous melt/pour and realized that I need darker shades when standing right next to the open furnace, to prevent getting sunburn in the eyes.

I bought some new #5 shade glasses, and also bought a #5 shaded lens for the faceshield.
I thought the #5 faceshield alone would be sufficient, but it was not, and I ended up needing both the #5 glasses and the #5 face shield when I was standing next to the open furnace.

The UV/IR being emitted by the open furnace and crucible at their maximum iron temperatures is really intense, so if you get into iron, take precautions, and note that the UV/IR is present even during the daylight, and is not visible, so you will not see it.

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Did you buy a polycarbonate faceshield lens?

 

It is plastic; not sure if it is polycarb.

I hold an old refrigerator shelf up in front of my faceshield when looking into the furnace, else the faceshield will melt.

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I wonder how the aluminized window tint film would hold up, I think it's something like Kapton polymide which is good up to 400 deg C. Whatever it is it has to be high enough temperature to withstand vacuum chamber aluminizing/sputtering where the aluminium is vaporized on hot tungsten filaments. You could have a wire frame to stretch it over.

Edit: The higher quality 10 year+ vacuum metallized films seem to be made of sterner stuff: no stretch for even the slightest compound curves, will stick to cylinders/flats only and are noticeably thicker.

Edit part 2: Window tint film looks to be biaxially oriented PET/Mylar, good for more than 250 deg C.

Edit part 3: Transparent copper metallized polymide/Kapton is something you can buy online from Alibaba: https://www.alibaba.com/product-det...pm=a2700.7724857.normalList.25.36a2ddc7MfYnsm

 

I think I am going to get one of those auto-darkening welding helmets.
I really need something that is clear when I am not looking at the furnace, and proportionally darker when I am close to it.
The problem with wearing two layers of No.5 shade is that the moment you walk away from the furnace, you can't see where you are walking (at night).

There is no way for me to avoid night pours, so the auto-darkening helmet may be a good solution, and would provide full-face protection at a high enough level to prevent eye sunburn.

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I have moved my videos back to the dreaded big-G, much as I hated to do that.
I was not having much luck with the other video channel; it just did not have the infrastructure to handle a lot of videos of the size I had, and I could seldom get them to play.

https://www.youtube.com/channel/UC9dVr4EIhHcFLIz0xY2bEXw/videos

I did not quite get them in the exact chronological order, but I did get the most of the ones I have posted.
I do not monetize videos; that is not what I am in it for; but rather I make them to leave a paper trail for what I have discovered about melting iron, and also as a reference so I can compare over time the changes I make to the process.
I don't care about view numbers either; I would rather have 10 views from people who have a genuine interest in casting metal than 10,000,000 view from rubberneckers.

This video illustrates the intensity that is coming out of the furnace when you open the lid (towards the end of the video), but it is actually much more intense than the video shows since the cameral lens gets overloaded.



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I like the large motor rewind video you posted Pat. Regarding the eye protection, there should be some optical bandpass material, maybe IR laser eye goggles that block high levels of heat. If you're casting at night, can you increase the levels of lighting around you with some floodlights so that your eye aren't coping with a huge change in illumination, I think anyone's eye will have trouble such a scene. It may well be that a silver window tint film which is optimized to reflect IR and UV combined with floodlights will shift the vision balance in your favour enough to work. That copper coated polymide film I linked earlier should be an excellent IR reflector but the orange cast seen through it would be a bit annoying in low light levels.

 

That was quite a project.
There were four of those in a floodwater pumping station, and they all had to be removed, transported to another state (Alabama), rewound, shipped back, and re-installed, all without flooding the part of the city that they protected.
The bearings were huge babbitt type, and each one took 5 people just to lift the bearing top half off.
Those motors are like 100 years old, but still work well.
I think they were 40,000 lbs each.

It was interesting finding the parting lines in the flywheels and such.

I think I am going to go with a self-darkening welding helmet, so I can see when I look away from the furnace.
Its the stuff I can't see (UV/IR) that I think is causing problems.