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Flashcards in Forming Deck (33):
1

What are the 4 different kinds of Bulk Deformation?

1) Forging
2) Rolling
3) Extrusion
4) Drawing

2

Advantages to Bulk Deformation

- No need to handle molten metal
- Very little material waste (if any)

3

Disadvantages to Bulk Deformation

- High forces required
- Machines and tooling is expensive (but is good for large production of parts)

4

What is Forging (definition)

Deformation is done with compressive forces applied through dies

5

What are the 5 different kinds of Forging?

1) Open Die
2) Closed die
3) Impression
4) Isothermal
5) Incremental

6

What is Open die forging?

Taking a cylindrical work piece and place it between 2 flat dies and press to reduce height

7

What is ideal deformation for Open die Forging

(homogenous deformation)
- volume remains constant
- reduction of height = increase in diameter

8

What happens in real life practice during Open die Forging

(Barreling)
- Caused by friction between material and die
- Can also be caused by thermal gradient between hot piece and cold die

9

What is Impression Die Forging

Workpiece acquires the shape of the die cavity while being deformed between 2 closed dies

10

Why is the flash gap important in Impression Die Forging

Because high pressure is generated in the filling of the cavity and it allows excess material to come out of the cavity

11

What is Closed die Forging

Workpice is completely surrounded by the dies

12

What could be a problem with Closed die Forging?

- Undersized volume of material won't fill the cavity completely
- Oversized volume of material caused die failure and jamming

13

What is Isothermal Forging

The dies are heated up to the same temp as the hot workpiece

14

Advantages and Disadvantages to Isothermal Forging

Advantages:
- Materials flow easier within the die cavities
- no need to cool the parts
- complex parts with good dimensional accuracy can be made
Disadvantages:
-EXPENSIVE AS FUCKK

15

What is Incremental Forging?

When the blank is formed through several small steps

16

Compared to conventional forging, Incremental Forging...

- Requires much lower forces
- Is a quieter operation
- Similar parts can be forges using the same dies

17

Coining

Slug is shaped in a completely closed cavity

- high pressure (5-6 x flow stress) used to produce fine detail with no lubricants

18

Heading

Upsetting is performed at the end of a rod to produce a shape with a larger cross section

-Highly automated
-Can buckle if Length -> Diameter ratio is too high

19

Piercing (punching holes)

Punch with a specific shape indents the workpiece and creates a shaped cavity or impression

20

Piercing Force depends on

- cross sectional area of the punch
- flow stress of the material
- tip geometry
- friction at the surfaces

21

Hubbing

a hardened punch with particular geometry is pressed into a work piece to produce a cavity shallower than piercing

22

Cogging (drawing out)

Thickness of a bar is reduced by successive steps
ex) incremental forging

23

Fullering and Edging

Used to distribute material to a specific region of the workpiece prior to forging

Fullering - material is distributed away from an area
Edging - material is gatherd in a localized area

24

Roll Forging

Cross sectional area of a bar is reduced or altered in a shape by passing through a pair of grooved rolls

25

Skew Rolling

Similar to rolling, but used to make ball bearings

26

Name the 5 defects that could happen during bulk deformation

1) Cracking
2) Laps
3) Cold Shuts
4) Warping
5) Improper formed sections & dead zones

27

Cracking?

Excess stress or uneven distribution of it

Caused by
- poorly designed forging die
- excess material in the workpiece
- high thermal gradient between piece and die

28

Laps

Buckling of the part

Caused by
- too little material in the workpiece

29

Cold Shuts

Metal Flowing at different temperatures meet (don't combine smoothly)

- indicated problem in the mold design with metal flow

30

Warping

Thinner sections cool faster than rest of forging

31

Improper formed sections & dead zones

- too little metal in the workspace
- flawed forging die design (incorrect material distribution)

32

Forging independent variables

- Material
- Starting geometry
- Lubrication
- Speed of deformation
- Amount of deformation

33

Forging dependent variables

- Force and power
- Exit temperature
- Dimensional precision