MIFCO furnace questions, answered

Shouldn't be with PE but remember a lot of products use stabilisers (UV, flame retardancy etc) so getting pure HDPE is questionable. PVCs and Styrene materials are NASTY!

 

HDPE plastic is about as clean a material to burn as you can get, way cleaner than used motor oil and such. Some researchers built an extrusion press so plastic bags could be turned into fuel logs that could be burned in a special furnace, but so far it hasn't gone anywhere. When burned there is virtually zero residue. So a continuous feed furnace is possible, without needing to deal with ash. The black HDPE we use has carbon black added for color so that goes off as CO2.

The MIFCO controls are just like on your house furnace and really very reliable. Remember this furnace sat for nearly 20 years in an unheated shed and after I cleaned the spiders out of the UV sensor and connected gas it fired right up.

 

It's more or less a pure hydo-carbon. It's chlorides that make other resins pretty horrible. Carbon black is used as a UV stabiliser (at least in polyamides) not sure if HDPE ever has a flame retadant added, not much call for it in milk bottles I guess.

Hell, we had a few guys on AA running furnaces on wood gas many years ago!

 

Well thats good to hear. wonder why we arent we burning shopping bags to make electricity?

 

They'll become a rare commodity in New York as of next year. No more single use shopping bags.
My favorite retired widow friend makes mats out of them. Takes hundreds of bags and many hours just to make one. She takes them to the bus station downtown and hands them out to homeless people. I guess she'll have to switch to using straws.
I use HDPE to make machinable wax and anytime I've ever seen it burn its nasty. How would you prepare it and actually burn it cleanly?

Pete

 

lol...

 

Post deleted to avoid having this thread being derailed into an environmental debate.

 

I fired up the furnace last night and poured 3 parts using the new tongs. Parts were all failures! I waa in a hurry to get done before dark and was running out of propane. Then when I did the pours the smoke was so bad I couldn’t see where I was pouring and quit too soon. All three were not filled completely. I should have poured one, pulled it out of the sand and checked it before pouring the next one.

The new tongs worked great though. Really easy to grab the crucible in the furnace and release it back in the furnace. I made a plinth block from a piece of fire brick like you’d use in a fireplace. I think it melted, was stuck to the bottom of the crucible and stayed there for the pour!

Raising the crucible 2” so the top was about touching the lid had a very positive effect. The metal melted much faster, and no I didn’t get the time because I was trying to do too much. Started the clock but didn’t check it. It was also much easier to charge the crucible and with the top cover open to charge it was not as hot working conditions. In fact I think I overheated the melt. Stuck the pyrometer in and it shot past 1600 in seconds.

I added 7% silicon to the melt and the parts are clearly better even though incomplete. I sawed the parts in half and there is almost no porosity, unlike the 6061 pour with no silicon. Surface finish was much better and there was no visible flow lines like last time.

 

The brick may have melted or the crucible might have melted. Certainly my super salamander Morgan crucible weeps some glass-like material each melt. Not a lot but perhaps a teaspoon or two end up on the plinth. A couple sheets of cardboard between the crucible and plinth solves the adhesion problem for me. Must be that the cardboard soots up the base of the crucible.

Good to hear the plinth helped efficiency. Gotta get that crucible into the hot part of the flame!

Denis

Edited out “doors” and replaced with “soots”. Sometimes autocorrect does some goofy stuff!!

 

Heat will melt/weld most materials together. A small amount of carbon will free or interrupt this. A thin cardboard is perfect. I think a few others here do that too.

 

Pictures of the failed pours will help.

 

oops... Sometimes you can get a plinth to let go of a crucible. Next time your up to temp, try twisting the crucible when it's in the furnace while there is weight in it and it should let go. I made this mistake only once and got lucky. A fat 3lb plinth would not be nice to have permanently attached to the south end of a heavy pot of metal.

 

Good to know about the cardboard, I’ll give that a try.

 

It really works. I put 2 pieces down every time I sit that crucible down when its hot.
No stick, I promise.

 

you are always supposed to sprinkle a handful of sand on top of the Plith before melting . every foundry has sand laying about Cardboard works too


V/r HT1

 

A handful of sand?—-20 melts later you have 20 handfuls of sand mixed in with whatever slag and slop is in the bottom of the furnace? The cardboard just burn away....

Denis

 

any excess sand , slag, slop [sic] should be blown out of the Drain hole of the furnace if not you scrap it out while hot at the end of each days pouring. you do clean out your furnace at the end of each day right??? that is the Navy way!


V/r HT1

 

Army here. 1970 to 72. Food inspection. We were taught to keep our equipment clean!

Denis

 

USAF 1995-2003. The only branch that purposely sends the officers out to die. lol...