Inert Atmosphere Ovens and Furnaces

When heating materials such as steel, aluminum, and certain plastics, oxygen in the air can react with the material and cause unwanted oxidation on the surface. This is due to the fact that oxidation occurs more rapidly at elevated temperatures. Steel, for example, will oxidize very quickly at temperatures above 450°F (232°C), resulting in dark, rust-like discoloration and surface roughness. Aluminum is very reactive with oxygen and forms a thin film of surface oxidation at room temperature. This film will become thicker at elevated temperature and is undesirable for certain end uses of the aluminum. Similarly, PTFE (Teflon), UHMW plastic, copper, and certain other materials are negatively affected by oxygen when heated. 

To mitigate this effect, ovens and furnaces specially designed for atmosphere heat treating, such as Wisconsin Oven’s inert Nitrogen Atmosphere furnaces, are used to process these materials. To create an inert atmosphere for heat treating, the heating chamber is flooded with nitrogen gas, which is non-reactive, to displace the oxygen and reduce oxidation on the surface of the material. The design utilizes a continuously welded shell to minimize infiltration of oxygen, special seals where accessories penetrate the oven shell, a sealed door design, and airtight cooling system that uses water passing through a heat exchanger to cool the furnace after the heating cycle is complete.

Inert Atmosphere Processing FAQs

What is an inert atmosphere oven or furnace, and what is it used for?

An inert atmosphere contains a very low percentage of oxygen, and thus will not readily react with materials contained in it. Since oxygen is the most chemically reactive constituent of air, the atmosphere in an industrial furnace or oven can be made non-reactive by removing the oxygen.

What materials are processed in an inert atmosphere oven?

Plastics, such as PTFE (Teflon), UHMW (Ultra high molecular weight) are sintered by heating in inert (low oxygen) atmospheres. Copper, steel, aluminum, and other materials are processed in an inert atmosphere furnace to reduce discoloration, scaling, or other oxidation on the surface.

What are the key design features of an inert atmosphere furnace that help maintain an oxygen-free heating environment?

Inert atmosphere furnaces and ovens remove most of the oxygen from the heating chamber, thereby reducing oxidation (surface scaling, discoloration, etc.) of the parts being heated. They utilize an airtight shell and special seals to maintain the inert atmosphere by keeping the oxygen out. They also include a nitrogen purging system to remove the oxygen from the interior, and a sealed cooling system to cool the oven before opening the door.

Is an inert atmosphere oven more expensive than a normal industrial oven?

Yes, in order to process parts in an inert atmosphere, the oven needs to have special features such as a sealed airtight shell, nitrogen control system, inert atmosphere cooling system, and special controls. An inert atmosphere furnace typically costs 30% to 50% more than a normal industrial oven.
 

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