Category: Mechanical Working Of Metals, Sheet Metal Work, And Powder Metallurgy

In a hot extrusion the metal billet is heated up to plastic state and put into a cylinder and it is forced to flow through the opening of a die. On the basis of direction of flow of the metal with respect to direction of the force applied, hot extrusion is divided into two classes—forward…

Extrusion is a primary shaping process in which a metal kept in a cylinder is forced to pass through the opening of a die. The metal is subjected to plastic deformation and it undergoes reduction and elongation during extrusion. There are two types of extrusion—hot extrusion and cold extrusion.

Upset forging is used to produce head in a bolt, screw, bar, etc. Only a certain portion of the material is deformed and rest is unaffected from the deformation. Upset forging generally employs split dies that contain multiple positions or cavities and may be opened and closed type. The heated bar or rod is positioned…

Press forging employs a slow squeezing action produced by mechanically or hydraulically operated press as compared to rapid impact blows of hammer in drop forging. The slow squeezing action penetrates completely through the metal producing a more uniform deformation and flow of metal during the process. In this process, there is maximum utilization of energy…

In this forging, the metal is deformed by impact of hammer or die and hot metal is forced to confirm the die shape. The proper flow of metal during the intermittent blows is ensured and operation is divided into a number of steps. Each step changes the shape of the workpiece progressively. For complex forgings more…

This is variation of impression die forging without flash (Figure 21.5b). It has better utilization of material than open flat dies, better physical properties, closer dimensional, tolerance, high production rate, etc. In impression die forging the heated workpiece is placed between two required shaped die and is pressed or hammered. During hammering or pressuring it…

In open die forging, the hot workpiece is placed between two flat dies and is hammered to produce the desired shape. There is no flow of metal in this process. This is a slow process and may be performed by presses in addition to hammer (Figure 21.5a). It is repeatedly manipulated between the dies until…