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Introduction to Basic Manufacturing Processes and ... - always yours

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Hot Working of Metals 291<br />

the punch forces the blank through the die opening <strong>to</strong> form a cup or shell. The multiple dies<br />

are also used <strong>to</strong> accomplish the stages in drawing process. Kitchen utensils <strong>and</strong> components<br />

of food processing industries are manufactured by this process.<br />

Punch<br />

Heated<br />

plate<br />

Die<br />

Die<br />

Heated<br />

cup<br />

Drawn part<br />

Drawn part<br />

15.12 HOT SPINNING<br />

Fig. 15.5 Hot drawing<br />

Hot spinning is a process in which pressure <strong>and</strong> plastic flow is used <strong>to</strong> shape material.<br />

Spinning may be either hot or cold <strong>and</strong> is generally carried over a spinning lathe. In both<br />

cases, the metal is forced <strong>to</strong> flow over a rotating shape by pressure of a blunt <strong>to</strong>ol as shown<br />

in Fig. 15.6. The amount of pressure of the blunt <strong>to</strong>ol against the disc controls the generated<br />

heat, which helps in forming processes.<br />

Sheet being<br />

spinned<br />

M<strong>and</strong>rel<br />

Compression<br />

pad<br />

Tail s<strong>to</strong>ck<br />

centre<br />

Head s<strong>to</strong>ck<br />

Form<br />

Block<br />

Tool post<br />

Pin<br />

Spinning <strong>to</strong>ol<br />

Fig. 15.6 Hot spinning<br />

QUESTIONS<br />

1. What do you underst<strong>and</strong> by mechanical working of metals?<br />

2. Define re-crystalline temperature.<br />

3. Differentiate between hot <strong>and</strong> cold working.<br />

4. Define hot working of metals. What are its advantages <strong>and</strong> disadvantages?<br />

5. Describe with sketches the three methods of hot working.<br />

6. Explain briefly the various methods of hot extrusion with neat sketches.

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