Download PDF of this page Print this page

Atmosphere Heat Treating Furnaces available with Thermal Oxidizer

  • Atmosphere Heat Treat Furnace
  • Bell type atmosphere heat treating furnace with retort
  • Belt furnace with hydrogen atmosphere
Click to enlarge

At high temperatures, chemical reactions take place on the part surface. These chemical reactions are driven by the atmosphere at this temperature. Common atmospheres are air or a part thereof; the absence of it, is vacuum. Atmospheres can be inert, oxidizing or reducing. Although most of the atmospheric processing furnaces are used only up to about 1650°C, some are in successful operation to temperature as high as 1900°C.

Furnaces with hydrogen atmospheres are used when a reducing and non-carbonizing atmosphere is needed; for example, in the heat treating of metals or powder ceramic processing. Nitrogen atmosphere are needed for the carbonization process of carbon fiber.

We build Atmosphere heat treating furnaces with retorts, muffles and cold walls. For smaller parts, retort furnaces provide superior process control for heat treatment of metal products to 1300°C/2400°F in inert and reducing atmospheres. Inert or reducing atmospheres protect metal parts from oxidation during high temperature heat treatments. In continuous furnaces, muffles are used to protect the ware. For very large sized parts, a cold wall construction may be economical to avoid the costly retort.

Molybdenum-wound hydrogen Atmosphere heat treat furnaces have become useful and necessary tools for both industry and research. For the manufacture of carbide tools and radio tubes, for wire drawing, metal sintering, brazing, heat treating and research, this furnace has found wide use. The necessity of a reducing and non-carbonizing atmosphere, however, somewhat restricts the work these furnaces may do.

Furnaces with stationary, horizontal, round retorts
Rapid heating and/or cooling of a retort will fatigue and age the alloy; therefore, leaving the retort stationary within this type of furnace during cooling helps to prolong life of the retort. Considering that for a hydrogen atmosphere furnace, one must have gas inlet and outlet tubes connected to the retort, having a stationary retort and atmosphere connections simplifies safety as well as furnace operation.

Furnaces with removable, horizontal, square or round retorts
The retort may be round or square at the customer’s choice. For lighter weight loads within the retort and where more rapid cooling of the retort load is highly desirable, this concept of a removable retort can be more ideal. This design is not recommended for Waukesha, however, because rapid cooling is likely to warp the plates on which you are sintering your bronze powder.

Large-volume bottom loading furnaces with vertical retorts
The retort that is lifted off the car after it rolls out from beneath the atmosphere furnace is ideal for large geometry loads and where rather precise temperature uniformity top to bottom is desired. For this furnace, the retort may either be left within the furnace all during cooling (or at any temperature if alloy fatigue is not a concern.)

Small to medium volume furnaces with stationary retorts
While the most expensive atmospheric processing furnace, it is capable of the very best temperature uniformity within the retort and allows for the very safest operation. This is one of the two types of furnaces proposed to Waukesha. Again, while it is the most expensive, it is the one furnace construction that will—without a doubt—achieve the very best temperature uniformity in situations that must reach maybe +/- 8°C depending on the desired heating and cooling cycle time.

General Capabilities:

  • Air, inert or reducing atmospheres available
  • Muffle, retort, or cold wall constructions available
  • Electric or fuel fired
  • Temperatures up to 1100°C—with metal allow muffles primarily for combustible or neutral atmospheres and when atmosphere dew point must be controlled
  • Temperatures up to 1750°C—with high purity oxide muffle and gas tight furnace shell; these furnaces are suitable for neutral or reducing atmospheres
  • Custom built to match temperature, atmosphere, width and length of your application

General Applications:

Furnace types available with atmospheres:

Contact Keith Company  to order an atmosphere heat treating furnace for your application, or to learn more about any of our products.