bulk forming processes

Question 1

Bulk deforming processes can be classified as

Answer 1

primary or secondary
processes
◦
Primary processes reduce a cast material into slabs, plates, and billets
◦
Secondary processes reduce shapes into finished or semifinished products

Question 2

Bulk deformation processes are those processes where

Answer 2

the thickness or
cross sections are reduced

Question 3

Rolling

Answer 3

Rolling operations reduce the thickness or change the cross section of a material through
compressive forces

Thick stock can be rolled into blooms, billets, or slabs

rollers can be shaped

steel, bronze, alloys

Question 4

Basic Rolling Process

Answer 4

Metal is passed between two rolls that
rotate in opposite directions

grain structure will be recrystallized

Question 5

how can we work in rolling

Answer 5

Hot Rolling and Cold Rolling
In hot

Question 6

hot rolling

Answer 6

◦
Temperature of the material should be uniform
◦
Rolling is terminated when the temperature falls to about 50 to 100 degrees above the recrystallization
temperature

Question 7

Cold rolling

Answer 7

products sheet, strip, bar and rod products with smooth surfaces and accurate
dimensions

Question 8

rolling mill configuration

Answer 8

regulating rollers will help keep everything linear; they help in stiffening without bending

Smaller diameter rolls produce less length of
contact for a given reduction and require less
force to produce a given change in shape

Question 9

Continuous (Tandem) Rolling Mills

Answer 9

Billets, blooms, and slabs are heated
and fed through an integrated series of
nonreversing rolling mills

Question 10

ring rolling

Answer 10

One roll is placed through the hole of a thick
walled ring and a second roll presses on the
outside

will roll into larger dia with less thickness

Question 11

Flatness Control and Rolling Defects

Answer 11

Rollers must be evenly spaced
throughout for perfectly flat pieces to
be produced

Sometimes this variation in roller
“flatness” may be desired

this is where backing rollers become important

Question 12

Forging

Answer 12

Processes that induce plastic deformation through localized compressive forces applied through
dies

Question 13

forging methods

Answer 13

Methods
◦
Drawing
◦
Upset
◦
Squeezed in closed impression dies

Question 14

Open
die Hammer Forging

Answer 14

Same type of forging done by a blacksmith but mechanical equipment performs the operation

Simplest: gravity drop machine
Computer controlled
can provide varying blows

Question 15

Impression
Die Hammer Forging

Answer 15

The dies are shaped to control the flow of metal

Upper piece attaches to the hammer and the lower piece to the anvil

Metal flows and completely fills the die

Question 16

Impression
Die Hammer Forging - flashing

Answer 16

Excess metal may squeeze out of the die
◦
This metal is called flash

Question 17

Alternatives to Hammer and Anvil Arrangement

Answer 17

Two hammers may form a workpiece
Impactors operate with less noise and less vibration

Question 17

Upset Forging

Answer 17

Increases the diameter of a material by compressing its length

Both cold and hot upsetting

Question 18

Press Forging

Answer 18

used for large or thick products

Slow squeezing action penetrates completely through the metal

Produces a more uniform deformation and flow

Longer time of contact between the die and workpiece

Dies may be heated (isothermal forging)

Presses are either mechanical or hydraulic

Question 19

rules of Upset Forging

Answer 19

Three rules of upset forging

1. The length of the unsupported material that can be gathered or upset in one blow without injurious
   buckling should be limited to three times the diameter of the bar.
2. Lengths of stock greater than three times the diameter may be upset successfully provided that the
   diameter of the upset is not more than 1.5 times the diameter of the bar.
3. In an upset requiring stock length greater than three times the diameter of the bar, and where the
   diameter of the cavity is not more than 1.5 times the diameter of the bar (the conditions of rule 2),
   the length of the unsupported metal beyond the face of the die must not exceed the diameter of the
   bar.

Question 20

Roll Forging

Answer 20

Round or flat bar stock is reduced in
thickness and increased in length

Little or no flash is produced

Question 21

Swaging

Answer 21

Also known as rotary swaging and
radial forging

Uses external hammering to reduce
the diameter or produce tapers or
points on round bars of tubes

Question 22

extrusion

Answer 22

Metal is compressed and forced to flow
through a shaped die to form a product with a
constant cross section

May be performed hot or cold

Question 23

Advantages of Extrusion

Answer 23

Many shapes can be produced that are not possible with rolling

No draft is required

Amount of reduction in a single step is only limited by the equipment, not the material or the
design

Dies are relatively inexpensive

Small quantities of a desired shape can be produced economically

Question 24

Extrusion Methods

Answer 24

Direct extrusion
◦
Solid ram drives the entire billet to and through a stationary die
◦
Must provide power to overcome friction

Indirect extrusion
force the die into the material and the material comes out the top

Question 25

Extrusion of Hollow Shapes

Answer 25

Mandrels may be used to produce
hollow shapes or shapes with multiple

Question 26

Hydrostatic Extrusion

Answer 26

High pressure fluid surrounds the workpiece
and applies the force to execute extrusion

High efficiency process

Temperatures are limited because the fluid
acts as a heat sink

Seals must be designed to keep the fluid from
leaking Figure

Question 27

Continuous Extrusion

Answer 27

Metallic and nonmetallic powders can be
intimately mixed

Continuous feedstock is fed into a grooved
wheel and is drive by surface friction into a
chamber created by a mating die segment

Question 28

Wire, Rod, and Tube Drawing

Answer 28

Reduce the cross section of a material by pulling it through a die
Similar to extrusion, but the force is tensile

Question 29

diff btween Wire, Rod, and Tube

Answer 29

Wire small dia
Rod large dia
Tube mandrel on the inside

Question 30

Tube and Wire Drawing
Tube sinking does not use a mandrel

Answer 30

for tube well use a floating plug not actualy a mandrel

Question 31

Cold heading

Answer 31

a form of upset forging

Question 31

Impact Extrusion

Answer 31

A metal slug is positioned in a die
cavity where it is struck by a single
blow

Metal may flow forward, backward or
some combination

The punch controls the inside shape
while the die controls the exterior
shape

Question 32

Piercing

Answer 32

Thick walled seamless tubing can be made by rotary piercing