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Different types of Thermal Processing Equipment explained

The three general equipment classifications for thermal processing equipment are:

  • batch

  • semi-continuous

  • continuous

Classification used depends upon the scope of production and the nature of the business.

 

While the science behind heat treatment remains principally the same, certain advantages can be achieved from particular oven and furnace types. As an example it is possible to carry out the annealing process in air furnaces, vacuum furnaces, and gas purged retort furnaces, amongst others.

Similarly the surface chemistry process of carburizing can be carried out in a range of equipment types including batch and continuous atmosphere controlled furnaces, pusher furnaces, or vacuum furnaces. The range of furnace types is extremely diverse.

 

So, if the furnace equipment type does not define the process, why should there be so many different options for users to choose from?

 

Other issues that influence the choice of processing equipment include:

 

  • Captive shops: These are in-house processes usually carrying out work of a similar nature where continuous processes and large-scale batch processes can be most economically employed.

  • Commercial shops: Usually carry out a variety of work for external customers where batch production allows the flexibility required to meet the demands of a wide number of processes.

  • The desire to achieve the final finished product compliance without the need for further processing.

  • Physical size of the component.

  • Mixed batch production.

  • Reduced surface oxidation.

  • Final surface finish for wear, corrosion and fatigue resistance

  • Reduced component deformation.

For example:

Automotive gears have been hardened and tempered for many years in standard gas carburizing and draw furnaces. Recent

advances in Low Pressure Carburizing for these components in a vacuum furnace have brought advantages to production cycle integration and component quality.

 

Aircraft components can equally be annealed in gas purged retort furnaces or in vacuum furnaces. The distinction often lies in the stage of the process, with annealing of raw or core material being carried out under controlled atmospheres, while finished components are processed in vacuum where there is a much greater need to maintain control of components shape, dimension and surface finish as well the material properties.

Furnace Types

The following gives typical examples of furnace types, but this is by no means an exhaustive list:

 

Integral Quench Furnaces

Roller Hearth Furnaces

Rotary Hearth Furnaces

Atmosphere Furnaces - Carburising

Atmosphere Furnaces - General

Laboratory Furnaces

Shaker Hearth Furnaces

Lead Baths and Salt Baths

Batch Air Furnaces - General

Tempering or Draw Furnaces

Slot Forge

Bell - Top Hat Furnaces

Mesh Belt Furnaces

Soaking Pits & Pit Furnaces

Billet Furnace

Drop Bottom

Muffle Furnaces

Bogie Hearth Furnaces

Drum Rotating

Box Furnace

Dryers

Tip Up or Tilt Furnaces

Brazing Furnaces

Electric Resistance Furnace

Tool Room Furnaces

Brazing Atmosphere Furnaces

Elevator Hearth

Oil Fired Furnaces

Tube Furnaces

Burn Off Oven

Fluidized Bed Furnaces

Ovens General

Car Bottom Furnace

Forging

Pot Furnaces

Gantry Furnace

Plating & Galvanizing Lines

Vacuum Furnaces

Continuous Bright Annealing Furnace

Gas Fired General Purpose Furnaces

Pusher Furnaces

Conveyor Furnace

Radiant Tube Furnaces

Creep Test Furnace

Sealed Quench Furnaces

Cryogenic Vessels

Recuperative Furnaces

Walking Beam Furnaces

Diffusion Furnaces

Retort Furnaces

Walking Hearth Furnaces

The following gives typical examples of process types, but this is by no means an exhaustive list:

Aluminium Solution Treating

CarboNitriding

Annealing

Nitro-Carburizing

Aluminizing

Hot Isostatic Pressing

Tempering

Quenching

Austempering

Plasma ION Nitriding

Sintering

Martempering/Marquenching

Local Heat Treatment

Solution Annealing

Neutral Hardening

Strip Annealing

Nitriding General

Precipitation Hardening

Vacuum Brazing

Vacuum Carburizing

Carburizing

Vacuum Furnaces

Gas Nitriding

Vacuum High Pressure Gas

Quench

Flame Hardening

Homogenization

Gas Quench

Vacuum Low Pressure Carburizing

Diffusion Bonding

Gas Quench High Pressure

Reheating

Harden/Quench and Draw Temper