Lecture 3

Question 1

What is metal forming?

Answer 1

deforms and reshapes metal under applied forces

Question 2

advantages of metal forming

Answer 2

can be fast

and can improve material properties

Question 3

disadvantages of metal forming

Answer 3

high forces required and only suitable for large scale production

Question 4

what is flow stress

Answer 4

force required to cause material to flow

Question 5

what is working

Answer 5

plastically deforminga material to enhance its shape or properties

Question 6

what is hot working

Answer 6

working under conditions where re-crystallisation happens with deformation

Question 7

what is cold working

Answer 7

work hardening occurs

• carried out at room temp
• faults in crystal lattice move and make deformation diffucult as now non-uniform shape

Question 8

what is warm working

Answer 8

reduction in flow stress but no recrystalisation

Question 9

advantages of hot working

Answer 9

• lower flow stress
• improved ductility
• large amounts of deformation possible

Question 10

disadvtanges of hot working

Answer 10

• heating cost

- poor tolerances

Question 11

advantages of cold working

Answer 11

• good surface finish and tolerances

- no heating required

Question 12

disadvantages of cold working

Answer 12

• more force required

- used for limited amount of deformation

Question 13

what is rolling

Answer 13

• squeezing of metal between two rolls
• breaks down coarse, brittle and porous grains
• recrystallises with smaller uniform grains

Question 14

different rolling types

Answer 14

• two high
• three high
• four high
• tandem rolling

Question 15

what is shaped section rolling

Answer 15

i beams rolled this way

- roling of H section parts

Question 16

what is gear/thread rolling

Answer 16

threaded fasteners made this way - improved strenght as favourable grain flow