View Full Version : What is a "muffled" oven?

01-04-2013, 07:10 PM
I was reading about heat treating steel and the article kept referring to a muffled oven/furnace.
What is the difference?

01-04-2013, 07:34 PM
Also known as a muffle furnace. Basically a furnace where there is no contact with the fuel. Electric furnaces are considered muffle furnaces. Gas versions heat through a wall or something that keeps flue gasses from reacting with the item being heated.

01-04-2013, 07:39 PM
Think of a brick wall between the flame and the product your heating so it is a more indirect spread of the heat instead of hot spots moving with the flames. Used in making of the glass for making of enamels when mixing the pigments and other additives, that can be burned or cause discoloring. Also used in some pottery firing and can be of a temporary nature.

01-05-2013, 02:32 AM
What I have normally seen called a muffle furnace is essentially a box made of firebrick, with a door on the front, and electric heating coils in deep grooves on the sides.

01-05-2013, 02:47 PM
Worked on furnaces for reduction of exotic metals. Metal powders were measured into inconel "boats", and lined up into a round tube that ran the length of the furnace. There were a number of tubes, and each one was capped both ends. The tubes were then filled with hydrogen and heated. (Yes I said hydrogen). Periodically the tubes were opened and the boats ejected and new boats pushed in.

Interestingly enough, when the tubes developed leaks where they exited the furnace, the hydrogen was left on, and the leaks arc welded. You knew when the tube was sealed as the hydrogen flame extinguished.

01-05-2013, 07:30 PM
Self sealing quartz tube furnace with HYDROGEN? Scary.

I've worked with tube furnaces as well. The system that I worked on needed to first contain methane/hydrogen, then oxygen, and then methane and alchohol vapor. Much work was involved making sure there was no risk of explosion, plus we had these 'catchers' so if the tube blew the ends would not go flying.