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Manufacturing Processes > Section 4: Bulk Deformation > Flashcards

Section 4: Bulk Deformation Flashcards

1
Q

Bulk Deformation

A

Metal forming operations which cause significant shape change by deforming metal parts whose initial form is bulk rather than sheet.
Causes plastic flow into the desired shape

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2
Q

plastic flow

A

permanent deformation when a material hits a critical stress value

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3
Q

What temperature processes is bulk deformation performed under

A

cold, warm, and hot working

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4
Q

Advantage of hot working bulk deformation

A

Significant Shape change

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5
Q

Advantage of cold working bulk deformation

A

Strength is increased

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6
Q

Primary benefit of bulk deformation

A

Little to no waste
little or no machining required

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7
Q

Four Basic Bulk Deformation Processes

A
  • Rolling
  • Forging
  • Extrusion
  • Wire and bar drawing
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8
Q

Rolling w/ goals

A
  • Slab or plate is squeezed between opposing ROLLS
  • the rolls act as compressive forces that reduce the crosssection (reduce thickness)
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9
Q

Forging

A

Work is squeezed and shaped between opposing DIES

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10
Q

Extrusion

A

work is squeezed through a die OPENING, thereby taking SHAPE of the OPENING

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11
Q

Wire and bar drawing

A

Diameter of wire or bar is REDUCED by PULLING it through a die opening

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12
Q

Difference between Extrusion and Wire & bar drawing

A

In extrusion the work is SQUEEZED through an opening to take the shape of that opening

In Wire & bar drawing the work is PULLED through an opening with the goal of reducing the diameter

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13
Q

4 Types of Rolling and their 2 respective bases and functions

A

Based on workpiece geometry:
- Flat Rolling: used to reduce the thickness of a rectangular cross-section
- Shape Rolling: Square cross section is formed into a shape such an I-beam

Based on Work temperature:
- Hot Rolling: can achieve significant deformation
- Cold Rolling: produces sheet and plate stock

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14
Q

4 types of Rolling and their bases

A

Workplace Geometry:
- Flat Rolling
- Shape Rolling
Work Temperature:
- Hot Rolling
- Cold Rolling

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15
Q

What is Thread Rolling

A

Bulk deformation process used to form threads on cylindrical parts by moving them between two dies

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16
Q

Benefits of Thread Rolling

A
  • Important for mass production of bolts and screws
  • Performed as Cold Working
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17
Q

Advantages of thread rolling over thread cutting

A
  • higher production rates
  • better material utilization
  • stronger threads and better fatigue resistance
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18
Q

Ring Rolling

A

Deformation Process in which a thick-walled ring of smaller diameter is rolled to form a thin-walled ring of larger diameter

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19
Q

Roll Piercing

A

Formation of internal stresses and cavity by compression of cylindrical part
Can be used for seamless tubing

20
Q

What is Forging

A

Deformation process in which work is compressed between two dies

21
Q

What is the oldest metal forming operation

22
Q

Common products of forging

A

engine crankshafts, connecting rods, gears, jet engine turbine parts

23
Q

What is Impact forging

A

Forge hammer - applies impact

24
Q

What is Press forging

A

Forge Press - applies gradual force

25
What is Open-die forging
work is compressed between two flat dies, allowing metal to flow laterally with minimum constraint to produce a desired cross-sectional shape
26
What is Impression-die forging
Compression of work piece by two dies - flash is created
27
What is Flashless forging
compression of a work piece in punch and die tooling - no excess flash
28
Importance of flash in impression-die forging
- As flash forms, friction resists continued metal flow into the gap, constraining the metal to fill the die cavity - In hot forging, metal flow is further restricted by cooling against die plates
29
Advantages & Limitations of Impression-die forging
Advantages: -higher production rates - less waste of metal - greater strength - Favorable grain orientation of metal Limitations: - Not capable of close tolerances - Machining is often required to achieve accuracies and features needed
30
Notes on flashless forging
- starting work volume must equal die cavity volume within very close tolerance - process control more demanding than impression-die forging - best suited to part geometries that are simple and symmetrical - often classified as a precision forging process
31
Types of forging hammers and functions
gravity drop hammers - impact energy from the falling weight of a heavy ram power drop hammers - accelerate the ram with pressurized air or steam
32
disadvantage of forging hammers
impact energy is transmitted through anvil into the floor of the building
33
What are forge hammers commonly used in
impression-die forging
34
In general, extrusion is used to produce what?
long parts of uniform cross-sections
35
two basic types of extrusion
-direct (or forward) - indirect (or backward/reverse)
36
Direct Extrusion
- starting billet cross section is usually round - Extrudate is determined by opening - as the ram approaches the opening, the remaining portion that cannot be forced through is called the butt - also called forward extrusion
37
Indirect Extrusion
- aka backward or reverse extrusion - lower rigidity of hollow ram - difficulty in supporting extruded product as it exits die - can produce a solid cross-section using a hollow ram only - can produce a hollow cross-section using a solid ram only
38
Advantages and Limitations of Extrusion
Advantages: - Variety of shapes possible, especially in hot extrusion - Grain structure and strength enhanced in cold and warm extrusion - close tolerances possible, especially in cold extrusion - potentially little to no waste Limitations: - part cross-section must be uniform throughout length
39
what is Hot extrusion and its goal
- prior heating of billet to above its recrystallization temperature - reduces strength and increases ductility of metal, permitting more size reductions and more complex shapes
40
what is the goal of Cold extrusion
- generally used to produce discrete parts
41
Impact extrusion
high speed cold extrusion
42
Difference between wire drawing and bar drawing
stock size, equipment, and terminology - Bar drawing: large diameter bar and rod stock - Wire drawing: Small diameter stock
43
Typical Drawing practice
-cold working - use round cross sections
44
Products of wire and bar drawing
- Wire: fencing, hangers - Rod stock for nails, screws, springs - Bar stock: metal bars for machining, forging, etc
45
Bar Drawing
-Accomplished as a single draft (the stock is pulled through one die opening) -Beginning stock has a large diameter and is a straight cylinder - requires a batch type operation
46
Wire Drawing
Continuous drawing machines consisting of multiple draw dies (4-12) separated by accumulating drums: - Each drum (capstan) provides force to draw wire stock through the upstream die - Each die provides a small reduction, so the desired total reduction is achieved by the series of dies - Annealing sometimes required between dies to relieve work hardening

Manufacturing Processes (7 decks)

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