Metal forging is the process in which metals are formed and shaped using compressive forces. The forces are delivered using hammering, pressing, or rolling.
There are a number of forging processes – cold forging, warm forging, and hot forging – which are classified by the temperature of the metal being worked with. Forging is one of the more pivotal metalworking processes in the metal manufacturing industry. It’s especially vital in the iron and steel industries and is viewed as a tremendous source of productivity.

Here are some of the more common methods used:
• Closed die forging
• Open die forging
• Cold forging
• Roll forging
Sheet rolling
In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness, to make the thickness uniform, and/or to impart a desired mechanical property. The concept is similar to the rolling of dough. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is known as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is known as cold rolling. In terms of usage, hot rolling processes have more tonnage than any other manufacturing process, and cold rolling processes have the most tonnage out of all cold working processes.
There are many types of rolling processes, including ring rolling, roll bending, roll forming, profile rolling, and controlled rolling.

Swaging is a forging process in which the dimensions of an item are altered using dies into which the item is forced. Swaging is usually a cold working process, but also be hot working.
As a general manufacturing process, swaging may be broken up into two categories:
The first category of swaging involves the extrusion of the workpiece, forcing it through a confining die to reduce its diameter, similar to the process of drawing wire. This may also be referred to as “tube swaging”.
The second category involves two or more dies used to hammer a round workpiece into a smaller diameter. This process is usually called “rotary swaging” or “radial forging”.

Wire drawing
Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s). There are many applications for wire drawing, including electrical wiring, cables, tension-loaded structural components, springs, paper clips, spokes for wheels, and stringed musical instruments. Although similar in process, drawing is different from extrusion, because in drawing the wire is pulled, rather than pushed, through the die. Drawing is usually performed at room temperature, thus classified as a cold working process, but it may be performed at elevated temperatures for large wires to reduce forces.

Tube Rolling
Roll forming is a simple yet efficient metal forming process, ideal for even the most complex shapes. The process involves a roll forming mill and starts at the coil feeder, where material – typically coiled steel – enters the line. Some applications require a pre-piercing operation prior to being roll-formed. Subsequently, the strip of sheet metal is passed through a set of forming rolls. Each forming roll only bends small parts of the bend until the final shape is obtained. This progressively shaping method prevents springback from occurring.
Tube rolling is the process of trying out a number of tubes in the same spot in an amplifier and selecting the one that sounds best to you. This can be very helpful in optimizing the tone of the amplifier. CAUTION: Tube amplifiers run on dangerous high-voltages and the tubes get very hot during operation.