Hot forging is performed at extreme high temperatures above the metal's recrystallization point to avoid strain hardening during deformation. This allows for production of discrete parts with low stresses, homogenized grain structure, and increased ductility. Disadvantages include less precise tolerances and possible warping during cooling. Cold forging is done below the recrystallization point, usually with softer metals like aluminum. It has advantages of improved dimensional control and produces net or near-net shaped parts but requires cleaner metal surfaces and stronger tooling.

1. Hotforging
The hot forging manufacturing processis performedat extreme high
temperature (up to 1150 °C for steel,360 to 520 °C for al-alloys,700 to 800
°C for cu-alloys). During hot forging, the temperature reachesabove the
recrystallization point of the metal. Thiskind of extreme heat isnecessary
in avoiding strainhardening of the metalduring deformation.
ADVANTAGES
1. Productionofdiscrete parts
2. Low to medium accuracy
3. Scale Formation
4. Low stressesor low work hardening
5. Homogenized grainstructure
6. Increased ductility
7. Eliminationof chemicalincongruities
DISADVANTAGES
 Less precise tolerances
 Possible warping of the materialduring the cooling process
 Varying metalgrainstructure
Cold Forging
Cold forging deforms metalwhile it is below its recrystallizationpoint.
Cold forging is generally preferred whenthe metalis already a soft metal,
like aluminum. Thisprocessis usually less expensive thanhot forging and
the end product requireslittle, if any, finishing work. The cold forging
manufacturing processis performedat room temperature.
ADVANTAGES
 Easier to impart directionalproperties
 Improved interchangeability
 Improved reproducibility

2.  Increased dimensionalcontrol
 Handles high stress and high die loads
 Producesnet shape or near-net shape parts
DISADVANTAGES
 Easier to impart directionalproperties
 Improved interchangeability
 Improved reproducibility
 Increased dimensionalcontrol
 Handles high stress and high die loads
 Producesnet shape or near-net shape parts
 The metal surfacesmust be cleanand free of scale before forging
occurs
 The metal is less ductile
 Residual stressmay occur
 Heavier and more powerfulequipment isneeded
 Stronger tooling is required