Rotary Retort Furnaces

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prodSingleMainImgPlchldr Rotary Retort Furnace revolving retort for pins, chain links or fasteners that need to be hardened, quenched and/or tempered

Rotary Retort Furnaces

Rotary Retort Furnace revolving retort for pins, chain links or fasteners that need to be hardened, quenched and/or tempered
Rotary Retort Furnace traditional carburizing may be used, hardening, quenching and/or tempered rotary retort furnace

When you look to purchase anything in life, you always feel more comfortable when you go to the experts. As an industrial furnace manufacturer, Surface Combustion has more than 100 years of experience with thermal processing and heat treat furnace systems. One such specialized type of equipment is for very small workpieces such pins, chain links or fasteners that need to be hardened, quenched and/or tempered. The furnace style is a revolving retort which is a horizontally oriented drum with internal flights that while rotating, it tumbles and conveys the load from one end to the other. This action of tumbling provides uniform heating and process gas distribution for very small and densely packed workloads.

Rotary Retort Furnaces - Product Description

Surface® Combustion’s rotary (also known as revolving) retort starts with a high-quality alloy retort or drum which is centrifugally cast. The drum is installed in an electrically heated or gas fired insulated chamber. Inside of the retort, an endothermic atmosphere is typically used while through hardening. The drum is electrically driven via a chain or a rack and pinion drive. Batch styles will convey the load (tumble) within the retort moving forward and then in reverse. The load enters and exits through the same opening. Continuous styles enter and exit through opposite ends. At the exit, an oil, polymer or water quench can be incorporated for the hardening process. For tempering, there is no quench involved. Traditional carburizing may also be performed. Boost diffuse carburizing where zone separation is necessary for different process step temperatures or carbon potentials is problematic in this style of rotary retort furnace. The Retorts of our rotary retort furnaces can be as short as 2 to 3 ft. in length and as long as 40 ft. in length. Diameters up to 6 ft. are also available. The operating temperature range is typically from 1400°F to 2400°F as this is a radiant/conduction style of heat transfer to the load.

Insulation used in the hot zone can be brick or fiber. Heating elements are traditionally rod overbend style that are electrically isolated from the steel casing. Gas fired model can be through indirect heated radiant tube or direct fired burners. In the first case, the annulus between the hot zone and the outer surface of the retort may be purged with a constant flow of nitrogen.

Quenching is of a dribble quench style meaning small quantities of parts are dropped into the quench at one time. Separation of the oil from the furnace atmosphere is done via oil cascades which create a wall of sorts. Typical agitation in theses style of quenches are via pumps and nozzles point at the surface of the belt which retrieves the free-falling parts and brings them up to the surface where they may be passed to a washing system prior to tempering. The oil can be heated via electric bayonet style heating elements and likewise is cooled after quenching to return the oil temperature to the setpoint.

Units have been provided with single and double retorts

Retort diameters available from 12 in. to 36 in.  with overall lengths up to 20 ft.

Normal loading (depending upon maximum operating temperature) can reach 300 lbs./ft³ bulk density

Units have been provided up to 1950°F  maximum operating temperature

Gas-fired and electrically heated units available

Batch and continuous designs available

Wide range of available companion equipment to meet your needs

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Cast Iron



Stainless Steels



Steel Shot

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Austempering Systems

Tempering Systems

Transfer Conveyors

Quenching Systems

Material Handling Solutions

Way Feeding Systems

Atmosphere Generator

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Ready to Get Started?

Please call us when you are ready to discuss a new furnace or maintain, upgrade or replace your furnace or any part of your furnace. At Surface, we look forward to helping you with any thermal processing needs.

Call Surface with the following information ready to initiate your furnace solution.

  • furnace cyclecycle
  • furnace operationoperation
  • hours per yearhours per year
  • available spaceavailable space
  • operating temperature rangeoperating temperature range
  • heat sourceheat source

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(800) 537-8980