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Annealing With Induction

What Is Annealing?

Annealing is a process used to release stresses and tensions in metals that may be present after various working procedures. This prevents warping or cracking of the part during its service life or in subsequent working operations. Annealing consists of three stages. The first is known as the Recovery Stage, where the material is heated to a temperature where the internal stresses of the material are relieved. Next is the Recrystallization Stage. At this stage, the material is held at a temperature known as the Recrystallization Temperature for a long enough time for new grains to begin forming. The stage may be absent in certain metals such as steel. Lastly, the Grain Groth stage is where the material is slowly cooled down to allow time for the new grains to form. The rate at which the material is allowed to cool determines the rate of grain growth.

Advantages of Annealing With Induction

Annealing, when done in a traditional furnace, involves holding the parts in the heat for enough time to bring them up to temperature, holding them at that temperature, and then allowing them to cool at a controlled rate. For most processes, this could mean transferring the parts between multiple furnacces for heating, holding, and cooling.

Here is where induction heating technology has the ability to turn the annealing process on its head. Induction can be used to anneal parts in a continuously moving line at high speed. This can be done with individual parts such as bullet casings, or inline with a mill for wire or tube drawing. Removing the bottleneck caused by furnaces from the production line allows manufacturers more freedom to control their line speed, and decreases idle time in other stages of the process.

Induction heating can be done very rapidly. This allows induction coils for annealing to be very short compared to furnaces or infrared tunnels. This is particularly pertinent in continuous annealing operations where induction heating may facilitate plant layouts that save considerable floor space.

Localized Induction Annealing

Induction technology also makes localized annealing possible. Localized annealing is when only a portion of the part is annealed while the others retain hardness. This is useful to manufacturers because they can anneal areas that require more ductility without losing the previous work hardening of the other portions. This technique is commonly used for the manufacture of ammunition and tools.

Hole punches that were previously through-hardened are locally annealed on the striking end.

Induction Annealing in a Controlled Atmosphere

Induction annealing is often accomplished without a controlled atmosphere. This is possible since induction heating typically requires only seconds and anneals the part before oxides are able to form. Even so, some processes may still require a controlled atmosphere. This is another area where induction technology shines. Induction creates heat in a part by inducting a current using a magnetic field. This magnetic field can permeate through materials such as quartz, glass, various plastics, and more. This makes heating in a controlled atmosphere incredibly easy because the inductor coil can be located outside of the atmosphere chamber. Induction technology also allows controlled atmosphere annealing to be done on a continuously moving line.

Annealing Industries & Equipment

Annealing is a common practice across numerous industries. Radyne Is experienced in producing high quality, cutting edge equipment for annealing tailored to fit the needs of diverse industries.

Ammunition Manufacturing

The ammunition industry commonly uses specialized annealing equipment to produce bullet casings with favorable metallurgical properties. When Producing bullet casings, the brass begins as a flat sheet which is punched out into short and stout cups. These Cups then undergo multiple drawing stages that form the body and neck of the casings. Between each drawing and forming stage, the casing must be annealed to prevent cracking. These Casing Annealing Systems need to be highly accurate to produce a consistent annealing profile. Failure to anneal a casing properly could lead to sub-par quality ammunition. Radyne is highly experienced in providing systems to anneal casings during every stage from cup annealing to the final neck taper anneal. Browse our selection of casing annealing equipment below, or click here to learn more about induction in the ammunition industry.

Radyne Casing Annealing System

The Radyne Casing Annealing System or CAS is designed for annealing casings during the neck taper stages. It comes in two sizes for medium or high throughput. This system utilizes a rotary table with an automatic collator and feeder system to facilitate easy loading and continuous operation. Precision induction coils and cutting-edge control firmware ensure a highly consistent annealing profile. Click the photograph to learn more about the Radyne CAS.


FlexScan 12 Used to Locally Anneal Large Brass Casings

FlexScan Pop-up Scanners

FlexScan pop-up induction scanners can be used to anneal large-caliber ammunition casings used in artillery and heavy weapons. The system has the ability to run two-up and is able to produce extremely precise annealing profiles by scanning the neck and body of the casing. Click the photograph to learn more about FlexScan Pop-up Scanners.


Wire Manufacturing

The wire and cable industry commonly utilizes induction annealing equipment to anneal wires in between and after the drawing stages to increase ductility and improve electrical conductivity. Induction technology is especially desirable for the annealing of wire because it is highly accurate and allows for annealing in a controlled atmosphere. Browse our selection of induction wire annealing equipment below, or click here to learn more about the wire manufacturing industry.

Bright Annealing Wire Line whole system overview

Bright Annealing Wire Line

The Radyne Bright Annealing Wire line is a turn-key system for annealing wire in a controlled atmosphere. It fits directly in line with today’s high-speed drawing and rolling lines. making them the preferred choice for lean, agile manufacturing.


Tube & Pipe Manufacturing

The production of tubes and pipes often requires annealing during or after forming or drawing. Both seamed and seamless pipes and tubes can require annealing to ensure the product has consistent and desirable metallurgical properties. Click here to learn more about tube and pipe manufacturing.

Also See: Weld stress relieving.

Dull Annealing Tube Line

The Radyne Dull Annealing Tube Line is a turn-key inline annealing system designed to anneal small diameter pipes and tubes in the open air. It fits directly in line with high-speed drawing and rolling equipment making it an ideal drop-in system for existing lines.


Continuous Induction Annealing

Bright Annealing Tube Line

The Radyne Bright Annealing Tube Line is the ideal system for annealing small diameter tubes and pipes in a controlled atmosphere. The system fits directly in line with high-speed drawing and rolling equipment and can be optioned with gas quench to eliminate post-annealing cleaning completely.