COLD and WARM FORGING EXTENDED RANGE PROJECTILES

All internal and external ballistics experts are aware of the unwanted effects that an anomalous mass distribution in the shell body of ordnance generates.

These unwanted effects usually provoke misalignment between the projectile’s rotation axis and geometric axis, turning into accuracy and range losses.

During the extended range projectiles’ manufacturing process, the most critical operation is the ogive or shell forming (forging) as it is a semi-free forging operation, in other words, external mould without inner support.

 COLD FORMING (FORGING)

The term cold forging may sound confusing. The process takes place at or near room temperature. Cold forging also involves just slightly heating up (warm) the metals to make them more malleable. Extreme heat is never used so that the metal is still being formed below the recrystallization point.

On pure ballistic flight projectiles (see fig.1), which are without extended range performances, or without trajectory correction support, shell bodies (ogives) are shorter and sharp shapeless geometry, having also higher walls thicknesses than extended range. On these projectiles, the semi-free (hot) forging manufacturing process is easier to control thanks to their own characteristics.

Extended range projectiles have much thinner wall thicknesses, shell bodies are longer (see fig. 2) and shaper shaped. Due to this and their specific characteristics, the walls thicknesses range tolerances are much smaller.

In high-performance, extended-range projectiles, a hot forging ogive process presents multiple drawbacks, having multiple parameters difficult to control.

To carry out this process with a guarantee of success, KA SAFE Engineering has developed a manufacturing process with which the thicknesses design requirements can be reached by complying with the required tolerances, carrying out a cold or warm forging process according to the characteristics of the required material.

This process consists of the following steps:

1. Study of the preform model necessary to reach the required thickness distribution

2. Conditioning of the material for the forging process

3. Surface application of the necessary products for the process

4. Cold or warm shell forging operation

 Cold and warm forging could suppress parameters which affect the result of the operation such as the following, allowing the model obtained after the shell forging process to be under control:

·      Temperature of the part in process

·      Tooling temperature

·      Uniformity of application of lubricating agents

·      Intermediate times between heating process and forging

In addition to the qualitative and quantitative advantages of the new process, thanks to the non-use of graphite and lubricating oils, which usually cause the widely known polluting effects in a hot forging process it is more environmentally sustainable.

Reach us at engineering@ka-safe.com