Bell Annealing Furnace by Therelek

Bell Annealer brings in excellent temperature uniformity, consistent quality and good production rates. Bell Furnace is suitable for black, bright and spherodized annealing of steel coils, non-ferrous strips, wires and general heat treatment processes up to 1100°C. Bright annealing of cold-rolled steel strip coils and heat treatment of medium and thick hot-rolled plate, long products and wire coils are done using a bell-type furnace.


Type of furnace is usually rectangular or cylindrical form, single or multi-stack gas or electrically heated. Continuous purging of ammonia is deployed throughout the annealing cycle to avoid decarburizing. Overhead crane is used to load the base and move the equipment. Coils are tilted to the right position and placed on the annealing base.

The convection and heat transfer occurs in the base assembly. Forced atmosphere circulation is used with the help of radial fans for temperature up to 950°C to improve convection. The cooling happens when the furnace is removed with inner cover acting as a protective atmosphere. In both strip annealing and wire annealing, the convection flow goes up on the sides and down the centre.

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Features & Specifications

Title Description
Temperature Range Up to 1100°C
Standard Applications Annealing, Wire Annealing, Isothermal Annealing
Insulation Vacuum Formed Ceramic Fibre Boards / Ceramic Fibre Blanket & Module / Refractory Brick Lining
Heating Media Options Electric/Gas Fired
Heating Elements Nichrome Wire / Special Alloy Resistance Heating Wire
Instrumentation options Thyristor, Programmable Temperature Controller, Temperature Recorder, PLC, SCADA, HMI





Bell type annealing furnace is widely used for annealing of steel coils. The coils can be of steel strips, steel wire or any other shape which can be loaded in the furnace.

Wire Annealing

Annealing involves heating the wire to a specific temperature before cooling it at a prescribed rate in order to achieve the desired result. Annealing is used with the goal of increasing the ductility of the wire and reducing the hardness. This allows the wire to be flexible while still remaining durable. With these properties, annealed wire is self-tying and can stay in place when wrapped around itself.

Why Choose Therelek Engineers?

The answer is simple, Therelek is the best in the business when it comes to custom built furnaces and commercial heat treatment. Customer satisfaction is a guarantee at Therelek.

Through continuous innovation, we have achieved both consistent quality and an impressive clientele across the globe; some of them have been working with us for many years now.

What you avail from us is not just a product but a trustworthy and beneficial vehicle for your success. No matter what the size or sector of your company is, when you work with Therelek, you can be rest assured.

More about Bell Annealing Furnace


  • Bright Annealing can be carried out with a broad range of materials.
  • It can be operated in Nitrogen atmosphere and also with 100% Hydrogen Atmosphere.
  • For fast cooling of the charge, the structure of the protective cover and furnace bases are designed and built for water-cooling.
  • An economical method of heat treatment when used with multiple bases.

Industries Served

  • Cold-drawn wire or hot-rolled rod
  • construction steels like
    • chain steels, spring steels
    • non-alloyed and low-alloyed grades cold-
    • work tool steel (ball bearing steels, etc.)
    • low and high-alloy hot-work tool steel and
    • high-speed steels (HSS)
    • high-alloy stainless Cr steels
  • Wire whose cross-section is not round (flat wire) can also be annealed.


What is Bell Annealing?

It is a cylindrical furnace in top hood design, that is the furnace kept on the fixed bases in the inverted position. An overhead crane of suitable capacity from one base to the another base carries the furnace itself. The Furnace shell will be of robust construction suitably reinforced with rolled sections. The furnace rests on the inner cover with ceramic fibre sealing in between. The inner cover rests on the base with neoprene seal in between for making the inner chamber gas tight.

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