Pre-Heat your Foundry Tools

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

GreenTwin

Well-Known Member
Staff member
HMEM Supporting Member
Global Moderator
Joined
Jul 2, 2021
Messages
3,862
Reaction score
1,536
Location
MidSouth, USA
Any metal implement/tool that comes in contact with molten metal must be preheated before contact is made.

This includes adding scrap to a furnace, preheating ingot molds, skimmers, ladles, etc.

Metal tools, ingot molds, etc. may appear to be perfectly dry, but apparently it has residual surface moisture, and so this moisture flashes when exposed to the heat of molten metal.
The result is usually an explosive ejection of metal.

I had this happen with a steel ingot mold that was not sufficiently preheated, and most of the gray iron in my mold popped out onto my jacket, where it ran down into my gloves, causing some nasty 3rd degree burns.

Be cautions if you attempt metal casting.

 
I had been involved in metal casting, both lead and aluminium. I would have been aware that the humidity is the most dangerous thing that can occur, that the metal explodes due to steam generation, whether it is in metal or in a mold that is not completely dry enough. Molten aluminum does not come out of the skin once it has landed on the skin so that you cannot shake the metal out of the skin. The most difficult thing I have experienced is properly drying the plaster before I cast it in the mold with aluminum until it finally boiled. It was not a good result that I gave up. Since then, I have made molds made of steel plates and steel pipes for aluminum casting when I made crankcases for model engines. After the casting was cooled, it easily came out of the steel mold.
 
The title of this thread could be "How to Burn Down Your Shed, in three easy steps", or "How to Not Light a Foundry Furnace".

There is no reason to light a furnace this way.



I would never do that inside the garage or workshop due to the lack of protection around the melting furnace and no dissipation of the heat above the melting furnace. The safest thing we can do is to be outside in a safe place without risking fire and problems with insurance that does not cover fire damage due to unreasonable use of the melting furnace.
 
One guy from a casting forum was operating his furnace inside his shop, but he had all the doors open, and so he assumed that there was sufficient ventilation.
He started feeling dizzy, walked outside, and collapsed in the snow.
He came to perhaps 30 minutes later, and was able to call 911, and get to the hospital.

The doctor said he had never seen anyone with such a low blood-oxygen level survive, so he was the first.

Low oxygen, as well as potentially toxic fumes are another very good reason to operate the furnace outdoors.

I have seen some in England operate a furnace that has a rear exhaust in the uppper back wall of the furnace, with an exhaust pipe through the wall, and a chimney up to above roof level.
I would not operate a furnace in a shed no matter what the conditions.

.
 
Any metal implement/tool that comes in contact with molten metal must be preheated before contact is made.

This includes adding scrap to a furnace, preheating ingot molds, skimmers, ladles, etc.

Metal tools, ingot molds, etc. may appear to be perfectly dry, but apparently it has residual surface moisture, and so this moisture flashes when exposed to the heat of molten metal.
The result is usually an explosive ejection of metal.

I had this happen with a steel ingot mold that was not sufficiently preheated, and most of the gray iron in my mold popped out onto my jacket, where it ran down into my gloves, causing some nasty 3rd degree burns.

Be cautions if you attempt metal casting.


When I had my foundry I would start fire in the curable. Let burn till curable was above 212°F .
After start the furnace I would heat the ingots and tools in front furnace exhaust.
Would buy leather coats fron Salvation Amry store .
Used a face shield and safety glasses with welders gloves

Dave
 
Better yet, get an IR gun type thermometer. Once I preheat an ingot mold and then had a burner issue, took a few minutes to get to the pour. In the mean time the mold had cooled enough for vapour to condense (the mold was still hot to the touch so it seemed fine.)


Long story short my copper/bronze ingots instead became bronze bb's and I got to see what red hot rain looked like.
 

Latest posts

Back
Top