Casting

Question 1

Smelting

Answer 1

extraction of metal from its ore through heating and melting.

Question 2

Casting applications

Answer 2

engine blocks, implants, prosthetics, jewellery pieces, sculptures, gears

Question 3

Casting advantages

Answer 3

complex geometries, net shape, large size difference, mass production,

Question 4

casting disadvantages

Answer 4

poor mechanical prperties, dimensional accuracy or surface finish. Unsafe.

Question 5

Cupola furnace

Answer 5

Vertical cylindrical furnace equipped with tapping spout near base

Question 6

Crucible Furnaces, indirect fuel-fired furnaces

Answer 6

no contact with burning fuel mixture. Used for nonferrous.

Question 7

Factors effecting the pouring operatins include

Answer 7

pouring temp, puring rate, turbulence

Question 8

Effects of pouring rate on pouring casting

Answer 8

too slow it will freeze. To fast will have the inclusions of slag, gas and turbulance.

Question 9

Effects of turbulance on pouring casting

Answer 9

accelerate formation of metal oxides, aggravate mould errosion.

Question 10

What does the mould consant depend on. Cm

Answer 10

Mould material, thermal properties of casting metal, pouring temperature relative to melting point

Question 11

shrinkage in solidification is caused by

Answer 11

level reduction due to liquid contraction, reduction due to solidification shrinkage, solid thermal contraction.

Question 12

name the 4 casting processes

Answer 12

 Expendable mould processes;  Permanent mould processes. Or Opena and closed moulds

Question 13

advantages and disadvantages of: Expendable mould processes

Answer 13

sand plaster. More complex shapes allowed. Slower productin

Question 14

advantages and disadvantages of: Permanent mould processes

Answer 14

reusable mould. Made of metal or ceramic. Higher production rate, geoletries limited

Question 15

What is shell moulding

Answer 15

expendable mould casting process that sand with resin binder to form the mould.

Question 16

Advantages of shell moulding

Answer 16

smoother cavity surface - > good flow. Accurate, minimize cracksm machanised

Question 17

DISAdvantages of shell moulding

Answer 17

MORE EXPENSIVE metal pattern, costly for small production.

Question 18

What is Investment Casting? (precision casting or lost-wax casting)

Answer 18

a wax pattern is used to shape a disposable ceramic mould, wax is metled out after. Invest means to cover completely. Has a pattern tree.

Question 19

Advantages of investment casting

Answer 19

complex shape, close dimentional control, surface finiah, reuse wax, net shape

Question 20

disAdvantages of investment casting

Answer 20

many steps, expensive.

Question 21

Advantages and disadvantages of permanent mould casting

Answer 21

dimentional control, rapid solidification. BAD: low melting point metals, simpler shape, high cost of mould

Question 22

Pressure Die Casting

Answer 22

[permanent mould] molten metal is injected into mould cavity under high pressure. Pressure is maintained during solidification. Hot chamber and cold chamber

Question 23

Gravity Die Casting

Answer 23

molten metal is poured into the mould from above, which fills from the bottom up, purely under gravitational force.

Question 24

Centrifugal Casting

Answer 24

mould is rotated at high speed so centrifugal force distributes molten metal to outer regions of die cavity

Question 25

Casting defects

Answer 25

blowholes, pinholes, misrun, missmatch, drop, spwell, metal panetraion, cold shut, hot tears, shrinkage cavity, wash and cuts, slag inclusions.

Question 26

Powder Metallurgy

Answer 26

parts are produced from metallic powders. GODO: no waste, net shape, many alloys, good properties, low temps/

Question 28

Upsetting

Answer 28

pre distributing the volume - Hydraulic Press. The first forging

Question 29

What is metal forming

Answer 29

plastic deformation is used to change the shape of metal workpieces.

Question 30

Hot rolling

Answer 30

above recrystallisation temperature

Question 31

Plane strain

Answer 31

The state in which the deformation (or strain) along a certain direction is zero

Question 32

What is the Draft

Answer 32

Change in thickness in rolling. Reduction is the percent reduced

Question 33

Forging: What is impression- die and flash die

Answer 33

Closed Die Forging. Impression is die cavity that is imparted to workpart - creates flash (push out). Flashless is work part is completely in die.

Question 34

Drawing

Answer 34

A operation in which the cross section of a bar, rod, wire, or tube is reduced by pulling it through a die opening.

Question 35

What are the 4 bulk deformation methods

Answer 35

Rolling, forgin, extrusion, wire drawing.