Manufacturing: Topic 2

Question 1

What is Plastic Deformation?

Answer 1

Metal is mechanically deformed below its fracture point but above its yield point.

Question 2

What is Hot Working?

Answer 2

The process whereby metals are plastically deformed above their recrystallisation temperature. Thus allowing the material to crystallise during deformation.

Question 3

What is Cold Working?

Answer 3

The process whereby metals are plastically deformed below their recrystallisation temperature. Forming is done at room temperature.

Question 4

What do you get when you cross and owl and a rooster?

Answer 4

A cock that stays up all night long.

Question 5

Cold Working leads to Hard Working

Answer 5

Metal deforms elastically then plastically. Planes of atoms slide over one another until they hit a dislocation. Further dislocations are also formed. (Process of work hardening)Eventually all slip planes are used. Material is fully work hardened, more work leads to fracture. Work Hardening can be reversed by heat treating (annealing) which causes re-crystallisation

Question 6

What is extrusion?

Answer 6

The process of pushing a billet through a die, to reduce its cross-section or to produce various solid or hollow cross sections.

Question 7

Why use cold extrusion?

Answer 7

Cold extrusion is capable of economically producing discrete parts in various shapes and with good mechanical properties and dimensional tolerances

Question 8

What is Forging?

Answer 8

Forging is the manufacturing process whereby metal is pressed/pounded/squeezed under great pressure into high strength parts known as forging. It is important to note that the forging process is entirely different from the casting process, as metal used to make forged parts is never melted and poured (as in the casting process).Hot forging improves material strength and toughness.Like making arrows/sword from a molten rod

Question 9

What is metal sheet working?

Answer 9

Cutting and forming operations on relatively thin sheets of metal

Question 10

What characterises sheet metal parts?

Answer 10

High strengthGood dimensional accuracyGood surface finishRelatively low cost

Question 11

Three main materials which are powder processed?

Answer 11

MetalsCeramicsComposits

Question 12

What is the 3 stages to powder processing?

Answer 12

Powder Mixing– Powder/s mixed with lubricationCompaction– Force appliedSintering– Heat applied in vacuum or controlled atmosphere– Inter particle bonding occurs

Question 13

Why blend powder with lubricant?

Answer 13

Reduce die wearMinimise friction between grains

Question 14

What is the most common type of compaction?

Answer 14

Cold CompactionCompression pressure between 150-1000 MN/m^2

Question 15

What is Sintering?

Answer 15

Fuses together powder particlesTime dependant (up to 24hrs)Vacuum or controlled atmosphere furnace

Question 16

What are composite materials?

Answer 16

For enforced mixing of different materialsEach Material may have different processing properties of its own

Question 17

Advantages of Particulate Processing

Answer 17

Good accuracy and surface finish Minimal wasteExtreme purity is possibleComposites can be made

Question 18

Disadvantages of Particulate Processing

Answer 18

Powder expensiveDifficult to store and keep pureUniform properties not guaranteed

Question 19

What is a phase diagram?

Answer 19

Multipurpose tools used to predict and understand material behaviour.Explains the correlation between material structure and mechanical properties.Plot of Temperature vs. Composition at a given pressure

Question 20

Allow Definition

Answer 20

A metallic allow is a mixture of two or more metals or non-metals. Ceramics can also be mixed to form alloys

Question 21

Component Definition

Answer 21

Components are the chemical elements of which the alloy comprises

Question 22

How many components does a Binary Alloy contain?

Answer 22

A binary alloy has two components

Question 23

How many components does a Ternary Alloy contain?

Answer 23

A Ternary Alloy has three components

Question 24

How many components does a Quaternary Alloy contain?

Answer 24

A Quaternary Alloy has four components

Question 25

What is a Phase?

Answer 25

A homogeneous portion of a system that has uniform physical and chemical characteristics. Sugar Solution is one phase, solid sugar is another

Question 26

What type of phase diagrams are there?

Answer 26

Binary IsomorphousBinary Eutectic

Question 27

What is Binary Isomorphous?

Answer 27

Isomorphous systems are the alloy systems which contain metals which are completely soluble in each other and have a single type of crystal structure.

Question 28

What is Binary Eutectic?

Answer 28

(Eutectic: Easy to melt) A homogeneous solid mix of atomic and/or chemical species, to form a joint super-lattice, by striking a unique atomic percentage ratio between the components — as each pure component has its own distinct bulk lattice arrangement.