Forming

Question 2

Different types of metal forming processes

Answer 2

• Hot forging
• Hot rolling
• Cold rolling
• Extrusion
• rod, tube & wire drawing

Question 3

What is the different between open die forging and closed die forging

Answer 3

(They are both types of hot forging)

open die forging (smith forging)
Involves free hand hammering
For low cost and quantity production

** closed die forging (drop forging)**
Heated metal shaped between two dies (specifically shaped ‘hammer’ like in the vids)

Question 4

Compare press forge over drop forge

Answer 4

+ more uniform deformation
+ better accuracy
- takes longer then drop forging
- cooling is require due to long contact times

Question 5

What forging is used to make bolts/screws

Answer 5

Upset forging, the material (strip) is gripped and the top is hammer down give the bolt head shape

Question 6

Forming process used for producing long uniform cross sections (flat bars, rails, rods, tube)

Answer 6

Hot rolling, material is driven between two rollers giving the desired shape

Question 7

Why would forming a thread be better than cutting it

Answer 7

As the grain would follow the shape of the material, giving it a stronger integrity. This is down by rolling the material between two rolling, it can be both hot or cold rolled.

Question 8

What temperature is hot rolling carried out at

Answer 8

At least 50% of the materials melting point, any lower and it’s considered cold rolling

Question 9

When would cold rolling be done

Answer 9

Usually after hot rolling, along with some weak H2SO4 to remove any oxides that may have formed. Cold rolling leave a better surface finish and allows for thickness control

Question 10

Explain extrusion

Answer 10

A material is pushed through a shaped die, which can produce complex parts with a constant section. Can be carried out hot or cold. Two types of extrusion are forward and backwards.

Forwards = rode
Backwards = tube

Question 11

What is drawing

Answer 11

The opposite to extrusion the material is pulled through the die, the limitation to this is the materials yield strength. It’s used to make wires drawn from rods.

Question 12

Sheet metal working methods

Answer 12

- Plain Bending
As known as angle bending (like folding paper in half but with a machine)
- seaming
Folding two sheet ends around each other to create a ‘seam’ (looks like snail pattern)
blanking/piercing
Blanking = desired piece is cut from sheet, the rest is scrape
Piercing = shapes are cut from piece to create desire piece, the cut outs are scrape
- Roll Bending
Run between 3 rollers bending the sheet
- Straigthening
Run between multiple rollers straightening the sheet
- Shearing
works the same as scissors
- Spinning
Sheet is spun and bend about an angle into desired shape
- Flow Turning
For cylindrical shapes ike turning but material in not removed just ‘stretched’, thickness decreases as a result
- Drawing
Held at both ends, pressed in the middle causing it to bend around tool (cups)
- Ironing
Same motion as drawing but pushed between die causing ‘stretching’ thinning
- Hydroforming
Uses hydrostatic pressure to draw the sheet
- Super Elastic Forming
Uses a vacuum to pull the sheet to the tools walls copying the tools inner shape

Question 13

What is work hardening

Answer 13

The increase in hardness due to cold working