The basic principle of wire drawing is to reduce the cross-sectional area of a metal wire by pulling it through a series of progressively smaller dies, while increasing its length and improving its surface quality.
How It Works (Step-by-Step):
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Starting Material:
A thick metal wire rod (often hot-rolled) is the input material. -
Tensile Force Applied:
The machine applies a tensile force (pulling force) to draw the wire through a die — a hard, cone-shaped tool with a small opening. -
Deformation Through the Die:
As the wire passes through the die, plastic deformation occurs:-
The wire's diameter decreases
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The length increases
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The wire becomes stronger and harder due to strain hardening
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Multiple Dies (Optional):
To achieve very fine wires, the wire may pass through multiple dies in a sequence (known as multi-pass wire drawing), each further reducing the size. -
Lubrication:
Lubricants (dry powder or wet oil-based) are applied to reduce friction, cool the wire, and protect the die.
Scientific Principle Behind It:
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Based on plastic deformation:
The metal is deformed beyond its elastic limit under tensile stress, allowing it to flow and change shape permanently. -
Governed by:
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Tensile stress > yield strength of the material
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Conservation of volume (reduction in cross-sectional area equals increase in length)
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