Ind Us Pro Presentation 2

8/3/2019 Ind Us Pro Presentation 2

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Classification of Forming

Processes

Mechanical and Metallurgical

Fundamentals and Rolling

Group 4


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Metal Forming

Metal forming is a shape production process(similar to casting)

But it uses the fundamental of deformation

processes. These processes is designed to exploit aproperty of engineering materials (mostlymetals) known as plasticity, the ability to flowas solids without deterioration of their

properties. Since all processing is done in the solid state,

there is no need to handle molten materials.


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The material is simply moved (or rearranged)to produce shape, then the amount of waste

is reduced substantially unlike cutting awayoperations.

Machinery and tooling can be expensive and

it is suitable for mass production.


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COMPRESSIVE FORMING: Rolling

Rolling is the process of reducing thickness (or

changing the cross section) of a long

workpiece by compressive forces appliedthrough a set of rolls.

The process of plastically deforming metal by

passing it between the rolls is known as rolling.

The work is subjected to high compressive

stresses from squeezing action of rolls.


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Grain Structure During

Hot RollingChanges in the grain structure of cast or of large-grain wroughtmetals during hot rolling. Hot rolling is an effective way to reducegrain size in metals, for improved strength and ductility. Caststructures of ingots or continuous casting are converted to a

wrought structure by hot working.


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Forging of Metals


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Types of Forging Dies

Three types of forging dies:

1. Open-die forging - work is compressed betweentwo flat dies, allowing metal to flow laterallywithout constraint

2. Impression-die forging (closed) - die surfacescontain a cavity or impression that is imparted toworkpart, thus constraining metal flow -flash is

created


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Types of Forging Dies

(cont.)

F

lashless forging (precision forging)-

workpartis completely constrained in die and noexcess flash is produced


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The forging process can be depicted by asolid workpiece placed between two flat dies

and reduced in height by compressing it.

Common names include upsetting or upset

forging

Open-die Forging


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Open-die Forging

(c) Deformation with friction. Note barreling of the billet caused byfriction forces at the billet-die interfaces.

(a) Solid cylindrical billet upset between two flat dies.

(b) Uniform deformation of the billet without friction.


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Closed-die Forging

The workpiece acquires the shape of the die

cavities while being forged between two

shaped dies.


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Impression-Die Forging

(a) through (c) Stages in impression-die forging of a solid round billet. Note the

formation of flash, which is excess metal that is subsequently trimmed off(d)

Standard terminology for various features of a forging die.


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Die Forging

Advantages and Limitations

Advantages compared to machining fromsolid stock:

Higher production rates

Conservation of metal (less waste)

Greater strength

Favorable grain orientation in the metal


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Die Forging

Advantages and Limitations(cont.)

Limitations:

Not capable of close tolerances Machining often required to achieve

accuracies and features needed, such as

holes, threads, and mating surfaces thatfit with other components


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Precision Forging

(flashless) Special dies are used to produce parts having

greater accuracies.

L

ittle excess material on the forged part(flashless)

Process control is more demanding thanimpression-die forging.

Best suited to part geometries that are simpleand symmetrical.


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Cogging / Smithing

Cogging also called drawing out, is basically

an open-die forging operation.

It is a process of reducing the thickness of abar by successive forging steps at specific

interval.

Blacksmiths perform such operations with a

hammer and anvil using hot pieces of metals.


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Cogging

Two views of acoggingoperation on a

rectangular bar.Blacksmiths usethis process toreduce thethickness of bars

by hammering

the part on ananvil. Note the

barreling of theworkpiece.

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