Metal forming is a manufacturing process in which forces are applied on raw material such that stresses induced in the material are greater than yield stress and less than ultimate stress.
The material experiences plastic deformation to change the shape of the component and converted to the desired shape of the component.
Forming process can be broadly classified into two types as cold working and hot working.
Deforming the material at a temperature below the recrystallization temperature of the work metal is called cold working. In cold working process, strength and hardness increases due strain hardening, but ductility decreases. Good surface finish and high dimensional accuracy are achieved. If cold working is higher than certain limits, the metal will fracture before reaching the desired shape and size. Usually cold working operations are performed in many steps with intermediate annealing operation.
Deforming the material at a temperature higher or equal to the recrystallization temperature of the work metal is called hot working. In hot working, refinement of grain size occurs, thus, improving mechanical properties. Even a brittle material can be hot worked. This requires much less force for deformation, but the finally formed surface finish and dimensional accuracy are not good. There is no work hardening.
- The amount of wastage of metal during metal forming process is negligible.
- Grain orientation is possible.
- Because of grain orientation the material is converted from isotropic to anisotropic material.
- In most of engineering applications it requires anisotropic material.
- Sometimes the strength and hardness of work material is increasing.
- Some other metal forming process, the surface finish obtained on the component is very good and excellent.
- Higher mount of force and energy is required for metal forming process compared to other manufacturing methods.
- Except the forging operation, all other metal forming process are used for producing uniform cross sectioned components only.
- The components with cross holes cannot be produced easily using metal forming process.