My Scribles

Classified into two as Hot Working & cold Working Hot Working: Deformation under conditions of temperature& strain rate such that recovery processes take place simultaneously .  Strain Hardening & distorted grain structure produced by deformation are very rapidly eliminated by the formation of new strain free grains as result of Recrystallisation .  ( Above Recrystallization Temperatures )  Very large Deformation possible because recovery process keep pace with the deformation.  Hot working occurs at an essential constant flow stress & because the flow stress decreases with increasing temperature.  Energy required is much less for hot working than for cold working.  Cold Working : Deformation carried out under conditions where recovery processes are not effective .  ( below Recrystallization temperature )  Strain hardening is not relieved in cold working.  Flow stress increases with deformation . Therefore the total deformation that is possible wit...

 Deformation zone is concerned with the distribution of stress , strain & particle velocities . & with overall pressure required to perform the operation .  Applied force must develop yielding in the material but the stresses must not locally create fracture.  Metallurgical phenomena such as strain hardening, Recrystallisation & fracture are important but often under specialised condition of high strain rate & temperature.  Flow stress of the material will be a strong function of strain , strain rate & temperature , often at values of these variable that are difficult to simulate in the laboratory .  w/p will be in contact with non deforming (elastic ) tools or dies . The Frictions along this interface & the heat transfer from the w/p to die are important consideration & also the tool wear & the surface finish of the product . Refer : George Dieter -Mechanical Metallurgy

Major Groups of processes are 1. Rolling Process. 2. Forging process 3. Drawing process 4. Extrusion process 5. Sheet metal forming process 6. High Energy rate forming process. Based on type of Force applied to the work piece as it is formed into shape . 1. Direct Compression Type Processes : force is applied to the surface of the work piece & the metal flows at right angle to the direction of the compression . Eg Forging & rolling 2. Indirect Compression Process : Eg Wiredrawing & tube drawing , extrusion & deep drawing of a cup. The primary force are frequently tensile , but indirect compressive force developed by the reaction of the w/p with die reach high value. 3. Tension type forming : Eg Stretch Forming : where the metal is wrapped over the contour of a die under the application of the tensile force . 4. Bending process : application of bending moments to the sheets . 5. Shearing process : Involves sufficient shearing forces of sufficient magni...

• Oldest manufacturing process. • Back bone of modern manufacturing industry . • Its could be primary product used as raw materials or finished final product . • Best eg . smith in villages. • Wire drawing process started in 1400 B.C • Some of metal forming operations are forging , rolling , drawing ,extrusion, sheet metal forming. • Combination of above process have been developed in order to manufacture economically greater variety of product shapes with desired shape , surface quality , dimensional accuracy & mech properties . • Earlier days metal forming was regarded as primary process & components shaped by forming were finished by grinding & metal cutting. • Development of hard materials for tools , dies components can now be made to near exact size thus minimizing machining. Importance of Forming Processes. Ease with which large part can be formed into useful shapes such as tubes , rod , sheets. Useful shapes may be generated in two basic ways 1. P...