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FORMING PROCESS
DEFORMATION PROCESS
METAL WORKING
FUNDAMENTALS OF COLD WORKING
Hot Working , Cold Working , Rolling , Forging, Extrusion,
Difference between Hot rolling and cold rolling processes
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Hot rolling
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Cold rolling
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1: Metal is fed to the rolls after being heated above the recrytallization temperature.
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1: Metal is fed to the rolls when it is below the recrystallization temperature.
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2: In general rolled metal does not shows work hardening effect.
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2: The metal shows the working hardening effect after being cold rolled.
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3: Co-efficient of friction between two rolls and the stock is higher, it may even caused shearing of the metal in contact with rolls.
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3: Co-efficient of friction between two rolls and the stock is comparatively lower.
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4: Experiment measurement are difficult to make.
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4: Experiment measurement can be carried out easily in cold rolling.
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5: Heavy reduction in area of the work piece can be obtained.
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5: Heavy reduction is not possible.
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6: Mechanical properties are improved by breaking cast structure are refining grain sizes below holes and others, similar deformation in ingot (get welded) and or removed the strength and the toughness of the job should increases.
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6: Hotness increased excessive cold working greatness crackers ductility of metal reduction. Cold rolling increased the tensile strength and yield strength of the steel.
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7:Rolls radius is generally larger in siz.
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7: Rolls radius is smaller.
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8: Very thin sections are not obtained.
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8:Thin sections are obtained.
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9: Hot roll surface has(metal oxide) on it , this surface finish is not good.
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9: The cold rolled surface is smooth and oxide free.
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10: Hot rolling is used un ferrous as well as non ferrous metals such as industries for steel , aluminum, copper , brass, bronze , alloy to change ingot into slabs.
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10: Cold rolling is equally applicable to both plain and alloys steels and non ferrous metals and their alloys.
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11: Hot rolling is the father of the cold rolling.
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11: Cold rolling follows the hot rolling.
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