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Manufacturing Process > Forming > Flashcards

Forming Flashcards

1
Q

What are the 4 different kinds of Bulk Deformation?

A

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

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2
Q

Advantages to Bulk Deformation

A
  • No need to handle molten metal

- Very little material waste (if any)

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3
Q

Disadvantages to Bulk Deformation

A
  • High forces required

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

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4
Q

What is Forging (definition)

A

Deformation is done with compressive forces applied through dies

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5
Q

What are the 5 different kinds of Forging?

A

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

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6
Q

What is Open die forging?

A

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

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7
Q

What is ideal deformation for Open die Forging

A

(homogenous deformation)

  • volume remains constant
  • reduction of height = increase in diameter
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8
Q

What happens in real life practice during Open die Forging

A

(Barreling)

  • Caused by friction between material and die
  • Can also be caused by thermal gradient between hot piece and cold die
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9
Q

What is Impression Die Forging

A

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

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10
Q

Why is the flash gap important in Impression Die Forging

A

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

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11
Q

What is Closed die Forging

A

Workpice is completely surrounded by the dies

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12
Q

What could be a problem with Closed die Forging?

A
  • Undersized volume of material won’t fill the cavity completely
  • Oversized volume of material caused die failure and jamming
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13
Q

What is Isothermal Forging

A

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

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14
Q

Advantages and Disadvantages to Isothermal Forging

A

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

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15
Q

What is Incremental Forging?

A

When the blank is formed through several small steps

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16
Q

Compared to conventional forging, Incremental Forging…

A
  • Requires much lower forces
  • Is a quieter operation
  • Similar parts can be forges using the same dies
17
Q

Coining

A

Slug is shaped in a completely closed cavity

  • high pressure (5-6 x flow stress) used to produce fine detail with no lubricants
18
Q

Heading

A

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
Q

Piercing (punching holes)

A

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

20
Q

Piercing Force depends on

A
  • cross sectional area of the punch
  • flow stress of the material
  • tip geometry
  • friction at the surfaces
21
Q

Hubbing

A

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

22
Q

Cogging (drawing out)

A

Thickness of a bar is reduced by successive steps

ex) incremental forging

23
Q

Fullering and Edging

A

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
Q

Roll Forging

A

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

25
Q

Skew Rolling

A

Similar to rolling, but used to make ball bearings

26
Q

Name the 5 defects that could happen during bulk deformation

A

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

27
Q

Cracking?

A

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
Q

Laps

A

Buckling of the part

Caused by
- too little material in the workpiece

29
Q

Cold Shuts

A

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

  • indicated problem in the mold design with metal flow
30
Q

Warping

A

Thinner sections cool faster than rest of forging

31
Q

Improper formed sections & dead zones

A
  • too little metal in the workspace

- flawed forging die design (incorrect material distribution)

32
Q

Forging independent variables

A
  • Material
  • Starting geometry
  • Lubrication
  • Speed of deformation
  • Amount of deformation
33
Q

Forging dependent variables

A
  • Force and power
  • Exit temperature
  • Dimensional precision

Manufacturing Process (8 decks)

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