Annealing, Cold Forging & Metallurgy in Manufacturing

By: Rich M.

Annealing is a part of metallurgical or materials sciences that is used in order to alter a material. The end result of the alteration evolves on the hardness and strength of the piece. The process is commonly seen to involve steps like heating above temperature then normalizing it. After which, cooling of the material will be necessary. It softens a material or induces ductility while shaping, forming or stamping it to the desired output.

Three stages are linked to the annealing process, namely:

Recovery phase. This is that point when the metal is softened by means of removing defects on the crystals and whatever internal stress the dislocation causes. This stage covers the instance before any stains or grains are seen on the material.

Recrystallization phase. This is the phase when new grains grow on the material. This is said to replace those that were deformed and removed during the recovery phase.

Grain growth phase. This stage results to a problem on the material. Since grains occur, there is a tendency for the output to coarsen thus making the metal less satisfactory than usual.

Annealing process

The annealing process is known by other names. It may often be referred to as intermediate, subcritical or in-process annealing. This is the cycle for heat treatment allowing the material to be more ductile or flexible without having the tendencies of breaking while it is worked at. The processes will involve rolling, drawing, spinning, forging or extruding. The material is heated first then will be set to cool down.

Several other processes may complete annealing. A full or a short cycle may be opted depending on the material being worked on. Materials such as silver, copper, brass and other alloys are also used in the process. The process is considered special because it does not have any complications with decarburization.

Cold Forging

Cold forging is a process in metal working that basically makes use of a pressing tool or a die. Whatever the shape of the pressing tool used in the process will also be the shape of the output. It is usually done in room or near room temperature. At some points, it is also known as cold heading.

Basic cold forging process

The simplest form of the cold forging process evolves on some steps. It starts when a bar or wire stock is placed at the stamping or pressing tool. The most common results are nails, screw with a head or a bolt. Once these outputs undergo another cold heading process, the shape may be changed to other forms. The most common examples are the heads of screw drivers or knurls.

More complicated cold forging processes

Aside from the process described above, there are other complicated processes behind cold forging. These things are described as follows:

Forward Extrusion. A punch is used in order to push the billet through a pressing tool. The material flows in a similar direction as that of the punch. This is commonly used in reducing wall thickness as well as in the production of solid shapes like circles, triangles and rectangles.

Backward Extrusion. Unlike in forward extrusion, this process takes the opposite direction going to the upper portion of the punch. This is famous in the production of inner and outer circular diameters or rectangles forming around a circle.

Side Extrusion. This process apparently goes in a sideways direction from the punch.

These are among the popular processes behind cold forging. Ironing, nosing, radial forging and upsetting may also be involved. A combination or a sequence of these processes may be employed in the production of an output. This will enable the manufacturer to produce different shapes and designs to the material.

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