EXTRUSION BASIC CONCEPTS Extrusion setup consists of a cylinder, a die plate, a plunger or ram Extrusion is a metal forming process involving shaping a metal billet (hot or cold) by forcing it through a die with an opening. Metal will take the shape of the opening. Pressure applied is either hydraulically or mechanically The dies are manufactured from hard alloyed steels It makes components, which have a constant cross-section over any length

EXTRUSION - vs - ROLLING Extruded parts can be had by the rolling process. The intricacy by extrusion is more than that of rolling Extrusion is a single pass process unlike rolling. Amount of reduction that is possible in extrusion is large (extrusion ratio 20 to 50) It is also possible to get shapes with internal cavities in extrusion by the use of spider dies Rolling

EXTRUSION APPLICATION Tubes, round or hexagonal rods, hose, casing, Al door- and window-frames. brass cartridge, structural shapes, aircraft parts, gear profiles, cable sheathing etc. are some typical products of extrusion. ****

Indirect extrusion requires a lower force than direct Two possible schemes… EXTRUSION DIRECT / FORWARD: - In this method the extruded metal flows in the direction of the ram motion. INDIRECT / BACWARD: - Here metal flows in the direction opposite to the ram motion. Indirect extrusion requires a lower force than direct process as there is no friction between the billet and inside walls of the container.

Another way of pipe extrusion is by spider die. Other Methods EXTRUSION To Produce Hollow and Semi-Hollow Shapes Tube extrusion: First solid ram moves through the heated metal billet creating a hole at centre Later a hollow plunger moves in Solid ram stays very close to the die. Another way of pipe extrusion is by spider die.

Indirect extrusion requires a lower force than direct Two possible schemes… EXTRUSION DIRECT: - In this method the extruded metal flows in the direction of the ram motion. INDIRECT: - Here metal flows in the direction opposite to the ram motion. Indirect extrusion requires a lower force than direct process as there is no friction between the billet and inside walls of the container.

BASIC CONCEPTS DRAWING The stress applied is tensile

DRAWING BASIC CONCEPTS Commonly used to make wires from round bars Process is very similar to extrusion Here the wire is pulled from the side where it emerges from the circular die instead of giving pressure from the back end.

DRAWING BASIC CONCEPTS Die is Converging Material is subjected to compressive stress within the die Dies are made of specially hardened tool steels, or tungsten carbide. Diamond dies are used for drawing very fine wires. Drawn rods are used as raw materials for making bolts etc. Wire drawing is used for producing wires Electrical wires, cables, strings, welding electrodes, fencing etc

WIRE DRAWING: DRAWING Material should be ductile since pulled by tensile force Wire is a drawn product having less than 5 mm. For wire drawing smaller diameter bar / rod stock is used. Usually done in multiple steps, using 4 to 12 dies, because of large drawn length. Wire drawing is a continuous process. *** Wire drawing is always a cold working process ***

WIRE DRAWING: DRAWING INITIAL PREPARATION: The cleaned (descaled, pickled in acid, washed in water), lubricated ( with lime and other lubricants) & pointed (by swaging operation) rod is fed into the drawing die. The tip is clamped into the jaws of the draw head and the drawing operation is carried out continuously. The draw-head moved by chain or hydraulic power pack. Draw speeds can be as high as 1500 mm/s. Series of dies used in tandem & finally coiled round a power reel. Maximum reduction in cross-sectional area per pass of drawing is restricted to 45%. (about 10% for steel and 40% for ductile materials such as copper.)

WIRE DRAWING: DRAWING DIE: MATERIAL for the Die for drawing may be made of tool steel, tungsten carbide (life 2 – 3 times that of alloy steel). For drawing fine wires, diamond die is used. BELL ASSEMBLY facilitates the entry of lubricant along with the wire. APPROACH ANGLE SECTION causes reduction in diameter. LAND or bearing region causes frictional drag on the wire, which helps in movement of the wire inside the die. BACK RELIEF provides space for expansion of the drawn wire.