Lectures 3-4 Processes Flashcards
Out of Sand, Investment and Die casting
Cost
L H H
Out of Sand, Investment and Die casting
Rate
M L H
Out of Sand, Investment and Die casting
Quality
L H M
Out of Sand, Investment and Die casting
Flexibility
M M L
Bulk deformation results in a massive — —- and used to work parts which have a high —- to —– ratio.
shape change, surface area, volume
Rolling is a process where the workpiece is
compressed between two rollers
Forging is a process where the workpiece is
compressed between two dies
Extrusion is a process by which the workpiece is
compressed or pushed into a die opening to take the shape of the cross-section
Wire or rod drawing is a process by which the workpiece is
pulled through a die opening
Sheet metal forming is usually called
pressworking
Bending is carried out by
using a punch in the shape of the bend desired
Deep/cup drawing is carried out in a similar method to
bending but is clamped on either side
Shearing is a process using a great enough
force to cause the metal to fail, like cutting it with scissors
Cold working is usually carried out —- the recrystallisation temp
below
Hot working is usually carried out —- the recrystallisation temp
above
When something is cold worked what occurs in the material?
Work hardening
Few pros of cold working
- Good quality surface finish
- Good dimensional accuracy
- No heating required so it is cheaper
Few cons of cold working
- Very high forces required
- Equipment is heavy duty and expensive
- Pre-cleaning required
- Tools wear out and need replacement
Few Pros for hot working
- Lower forces and power required
- No unnecessary strengthening of part
- Properties of part are usually isotropic
- Large amounts of deformation are more possible
Few cons to hot working
- Lower accuracy
- Higher total energy
- Poor surface condition
- Shorter tool life
An ingot can be rolled into what?
bloom, slab
A bloom can be rolled into what?
slab, billet
Difference between a forge hammer and forge press
Hammer applies an impact load,
press applis a gradual load
Barelling or pancaking is the result of which process
open die forging
Pros to open die forging
- Simple dies
- Wide range of part sizes
Cons to open die forging
- Limited to simple shapes
- Machining to final shape necessary
Impression die forging is the process by which the workpiece is
pressed between two dies that have the imprints
Differences in the grain flow between cast, machined and forged parts
Cast - no grain flow
Machined - broken grain flow
Forged - true grain flow
Upset test defines the materials ability to
resist surface cracking when reduced in height
Hot twist test defines the materials ability to
turn before failure
Precision forging is carried out by
enclosing the workpiece within the upper and lower punches and two dies either side
Swaging is the process by which the tubes diameter is reduced
by dragging through a narrowing die
Heading/upset forging is the process by which
the end of the wire is widened in CSA to form a head
Coining is a process to create
slight indentation onto a metal surface
Roll forging is a way to create
grooves and indents into a bar
Orbital forging is a process where
the top die with the indent has a circular motion
