The metal is formed to make bars and ingots, or it may be formed to make a final product. At iron and steel foundries, this process is normally referred to as “metal coating” or “coating.” Bars and ingots, such as those produced in the secondary lead and aluminum industries, may be sent to another facility to make a final product. In some industries, such as at iron and steel foundries, the metal is cast into a final product at the melting facility.

Forming the metal into a final product requires the use of molds and cores. Molds are forms used to shape the exterior of castings. Cores are shapes used to make internal voids in castings. In the iron industry, molds are prepared from wet sand, clay, and organic additives, and are usually dried with hot air. Cores are made by mixing sand with organic binders or organic polymers and molding the sand into a core. Some cores are baked in an oven.

After the metal is formed, it is removed from the mold or container in which it was formed. If the formed metal is a final product, it may be necessary to grind or sand off rough edges. Also, the metal may be shot-blasted to remove mold sand or scale.

Plastic Deformation Processes induce shape changes on the workpiece by plastic deformation under forces applied by various tools and dies.

Bulk Deformation Processes involve large amount of plastic deformation. The cross-section of workpiece changes without volume change. The ratio cross-section area/volume is small. For most operations, hot or warm working conditions are preferred although some operations are carried out at room temperature.

Plastic Deformation Processes induce shape changes on the workpiece by plastic deformation under forces applied by various tools and dies.

Bulk Deformation Processes involve large amount of plastic deformation. The cross-section of workpiece changes without volume change. The ratio cross-section area/volume is small. For most operations, hot or warm working conditions are preferred although some operations are carried out at room temperature.

Classification of Bulk Deformation Processes

Basic bulk deformation processes

(a) rolling, (b) forging, (c) extrusion, (d) drawing

• Rolling: Compressive deformation process in which the thickness of a plate is reduced by squeezing it through two rotating cylindrical rolls.

• Forging: The workpiece is compressed between two opposing dies so that the die shapes are imparted to the work.

• Extrusion: The work material is forced to flow through a die opening taking its shape.

• Drawing: The diameter of a wire or bar is reduced by pulling it through a die opening (bar drawing) or a series of die openings (wire drawing)

Sheet-Forming Processes. In sheet metalworking operations, the cross-section of workpiece does not change—the material is only subjected to shape changes. The ratio cross-section area/volume is very high. Sheet metalworking operations are performed on thin (less than 6 mm) sheets, strips or coils of metal by -means of a set of tools called punch and die on machine tools called stamping presses. They are always performed as cold working operations.