HOT WORKING OF METALS
*The mechanical working of metal above recrystallization temperature but below the melting point is known as HOT WORKING.
*In this process, the metal is heated above the recrystallization temperature of the metal but below the melting point of metal. Normally the recrystallization temperature of the metal will be about 30 to 40% of its melting temperature.
Types of Hot Working Process
1. Hot Forging
2. Hot Rolling
3. Hot Extrusion
4. Drawing
5. Swaging
6. Hot spinning
COLD WORKING OF METALS
*The plastic deformation of a metal to the required shape being performed below the recrystallization temperature is known as cold working process.
Types of Cold Working Process
1. Drawing
2. Coining
3. Bending
4. Knurling
5. Extrusion
6. Swaging
1.DRAWING
*The cold drawing is used to draw the tubes, rods and wires.
1. Blank Drawing
2. Tube Drawing
3. Embossing
4. Wire drawing
5. Metal Spinning
2. COINING
*It is cold working sizing operation. It is used for the production of metals and coins. The coining process consists of die and punch.
*By using the punch and die, the impression and images are created on the metal.
*The pressure involved in coining process is about 1600 Mpa.
*The type of impression is formed by compressive force.
3. SIZING
*This operation in cold working is used to size the metal into the required shape.
4. SWAGING
*The rotary swaging is also known as simple swaging. It is an interesting cold forging operation used for producing rounded components through radial impact forces by reciprocating dies.
5. KNURLING
*Knurling its performed on a lathe with hardened rolls. The surface of the rolls is a replica of the profile to be generated.
*The rolls are pressed radially against the rotating workpiece. It is used to make grip on the handles in a machine.
6. EXTRUSION
*In this type of extrusion process, the mandrel is connected to the ram, and the hot metal billet is placed inside the cylinder and the ram is pushed.
*When the ram is pushed, the mandrel presses through the die opening. It will produce the hollow tube.
