Drawing – It is a process where a cross-section of solid rod, wire, or tubing is reduced or changed in shape by pulling it through a die.

Drawing Process In this process the cross section of a round rod or wire is typically reduced or changed by pulling it through a die Die angle has great influence on the drawing force and the quality of the drawn product Drawing FORCE : F = Yavg Af In (Ao/Af) ; Yavg – average true stress of the material in the die gap Fig : Process variables in wire drawing. The die angle, the reduction in cross-sectional area per pass, the speed of drawing, the temperature, and the lubrication all affect the drawing force, F.

Tube Drawing Operations Fig : Examples of tube-drawing operations, with and without internal mandrel. Note that a variety of diameters and wall thickness can be produced from the same initial tube stock (which had been made by other processes).

Die Design Characteristic features of a typical die design for drawing Fig : Terminology of a typical die used for drawing round rod or wire. Fig : Tungsten-carbide die insert in a steel casing. Diamond dies, used in drawing thin wire, are encased in a similar manner.

Die Materials Commonly used materials are Tool Steels and Carbides Diamond dies are used for fine wire. For improved wear resistance, steel dies may be chromium plated, and carbide dies may be coated with titanium nitride For Hot drawing, cast-steel dies are used

Lubrication Proper lubrication is essential in drawing, in order to improve die life, reduce drawing forces and temperature, and improve surface finish. Types of Lubrication Wet drawing : Dies and Rods are completely immersed in lubricant Dry drawing : Surface of the rod to be drawn is coated with a lubricant Coating : Rod or Wire is coated with a soft metal that acts as a solid lubricant

Defects and Residual Stresses Typical defects are center cracking seams Fig : Schematic illustration of roll straightening of a drawn round rod.

DRAWING EQUIPMENT Fig : Two views of multistage wire-drawing machine that is typically used in the making of copper wire for electrical wiring.

Deep drawing operation is frequently used in the production of one side shut cylindrical cups and similar items in industry. The sheet piece which will be formed in that production operation, has been set into die as seen in Figure 1-a and apply pressure with a blank holder vertically. Then the sheet between blank holder and die is transformed into cup under plastic deformation, by applying a vertical pressure by a punch which moves vertically to the workpiece

Deep drawing The process is used to produce – hollow parts of all shapes where the wall thickness is the same as that of the bottom

Roller forming