Metal Flashcards
(84 cards)
1
Q
Main metals used for food packaging:
A
Aluminum
Iron
2
Q
Mineral sources of iron (ores):
A
hematite
magnetite (highest %)
limonite
siderite
3
Q
Ore source for aluminum:
A
Bauxite
4
Q
True/False: there is greater amounts of iron than aluminum in the Earth’s crust
A
False
Al is 8.1%, Fe is 5%
5
Q
Iron is usually transformed into ____ for food packaging
A
steel
6
Q
the raw materials for steel production: (3)
A
C (Coal)
CaCO3 (limestone)
Fe2O3 (iron ore)
7
Q
What is slag? how is it made
A
CaSiO3
made from CaO (from limestone) + SiO2
8
Q
in making iron into steel, you need to reduce __, ___, ___, ___, and add ___, ___, ___
A
reduce Si, C, P, S
Add Mn, Ni, Cr
9
Q
An increase in % of Carbon in steel will have what effect on the properties?
A
increase in hardness, tensile strength
decrease in ductility and welding properties
10
Q
What can be added to steel to increase corrosion and abrasion resistance?
A
Cr
11
Q
What steel component will increases hardness/tensile strength, especially at high temperatures?
A
Mo
12
Q
What is the effect of increasing Mn in steel?
A
increase strength and hardness
13
Q
What is the effect of increasing P in steel?
A
increase strength and hardness
decrease ductility
14
Q
What is ductility?
A
ability to be stretched into a wire
15
Q
What is the effect of increasing Ni and Cu in steel?
A
increase toughness, tensile strength, hardness, corrosion resistance
16
Q
What are common types of steel for food packaging? (4)
A
Type L (high purity, low P/residual metals) Type MR (higher P/residual metals) Type D (Low C, high S, stabilized) Type Ni (Added Ni)
17
Q
What steel is used for highly corrosive products?
A
Type L
18
Q
What steel are drawn and ironed cans made from?
A
Type D
19
Q
What is Ni steel used for?
A
Can ends, aerosol domes
20
Q
What is Type MR steel used for?
A
mildly/non corrosive products (low acid)
21
Q
What is used to describe metal hardness?
A
temper
22
Q
the different temper grades:
A
T1 (46-52) - soft, for deep draws T2 (50-56) - moderate draws, closures T3 (54-63) - shallow draws, gen. purpose T4 (58-64) - bodies/can ends T5 (62-68) - bodies/can ends
23
Q
What temper grades can be used for can bodies and ends?
A
T4 or T5
24
Q
What are types of plating steel?
A
Electrolytic tinplate (ETP)
Chromium coated steel
Polymer coated steel
25
What is ETP?
```
electrolytic tinplate (plated steel)
tin-iron alloy later at interface of tin/steel -> gives corrosion resistance
```
26
Steps for preparing ETP: (4 steps)
electrolytic process: bathe tin sulfate in sulfuric acid
thermal treatment (260-270C) & rapid quenching
chemical passivation in Na dichromate solution
apply oily lubricant
27
advantages (5) vs disadvantages (2) of chromium coated steel?
good: spontaneous passivation (thinner), cheaper, better heat resistance, coating adhesion, printing
bad: low abrasion resistance, decrease resistance to corrosion
28
What is polymer coated steel coated with? What does this achieve?
Polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), fluorinated perfluoroethylenepropylene (FEP)
resist abrasion, corrosion, food interactions
29
For a highly acidic food, what would be a good steel coating?
polymer coating (PTFE, PFA, or FEP)
30
2 processes needed to convert aluminum ore into aluminum:
1. Bayer process
| 2. Hall heroult process
31
Requirements of the Hall Heroult process:
cryolite (Na3AIF6)
| huge amount of energy needed
32
The bayer process converts ___ into _____
Bauxite
| alumina
33
Aluminum can be combined with many metals such as _______, to form various ____.
Mn, Si, Fe, Mg, Cu, Cr
| alloys
34
Magnesium in aluminum alloys will increase _____ but decrease _____
increase mechanical resistance
decrease corrosion resistance
35
What can be added to aluminum alloys to increase corrosion resistance?
Mn
36
List in order of increasing mass thermal capacity: Aluminum, carbon steel, stainless steel
stainless steel < carbon steel < aluminum
37
True/False: steel has a greater thermal expansion than aluminum
False; aluminum has greater thermal expansion
38
which is a better conductor, steel or aluminum?
aluminum (>carbon steel > stainless)
39
true/false: aluminum has a higher melt point than steel
false
40
which is more dense, steel or aluminum?
steel
41
Which has a higher tensile strength, steel or aluminum?
steel
42
2 types of cans:
2 piece
| 3 piece
43
Parts of a can:
Top: canner's end
Canner's end seam
body (side seam, side wall beading)
bottom: manufacturer's end
manufacturer's end seam
44
True/False: expansion panels are found in all metal cans
False: only in thermally processed cans
45
What types of can body seams are there?
welded seam
soldered seam
46
The can bottom is sealed by _____ while the top is sealed by ______
the maker
the canner (after filling)
47
A ____ seam joins the ends to the can body
double
48
3 piece can production steps (7 steps)
1. tin steel cut in large pieces, laquer & dry
2. cut pieces for ends & body -> rolled
3. form side seams
4. ends curled, one end filled with sealing compound
5. body flanged (may be beaded)
6. bottom attached
7. test for leaks
49
What is the purpose of beading cans?
strength in heat processing
50
What are can flanges?
ridges at can body rim, for clinching with can ends
51
How are side seams on cans formed, for thermally vs nonthermally processed?
welded electrically, laquered
| clinched in non-thermally processed products
52
Describe the process of electric welding for cans
electric resistance seam welding:
can pressed (force) between two copper electrodes (applies heat)
then coat with laquer and test integrity
53
Reasons to lacquer cans? (5)
```
improve can appearance
increase shelf life
cost reduction in steel
corrosion resistance
prevent color/flavor change in food
```
54
requirements for can lacquers: (7)
nontoxic
don't affect flavor/color of food
good barrier between food/container
easy to apply
doesn't peel off during processing or storage
mechanical resistance to manufacturing operations
economical
55
Examples of coating types for cans:
```
acrylics
alkyds
epoxys
butadiene
phenolics
vinyls
oleoresins
```
56
What is a can coating that has recently raised consumer concerns? Why?
```
Bisphenol A (BPA)
synthetic estrogen activity? (endocrine disruptor); possible leaching into food
```
57
What type of coating is fruit enamel, and what is it used for?
oleoresinous
dark berries/cherries that need protection against metallic salts
58
What type of coating is used for corn, peas, and other sulfur-bearing products? What type is it?
C-enamel
Oleoresinous with suspended zinc oxide
59
What is citrus enamel used for and what type of coating is it?
citrus products and concentrates
modified oleoresinous, polybutadienes
60
What is beverage can enamel used for, and what type of coating is it?
veg juice, red fruit juice, corrosive fruits, non-carbonated beverages
2-coated with resinous base and vinyl top coat
61
What is done in preparation of attaching the can end to the body?
1. curl can end
2. fill with sealing compound (act as gasket to help seal)
3. flange can body
62
A completed double seam on a can will be ____ layers thick at its thickest point
5
63
The steps of double seaming (2)
First operation:
chuck presses cover down on can
seaming roll will push end curl around flange
Second operation:
seaming roll + chuck will push seam flat
64
What materials can be used for 2-piece cans?
steel (type D) for thermally processed product
aluminum alloy for beverages
65
Different processes to make 2 piece cans: (4)
shallow draw (sides < diameter)
draw & redraw (sides > diameter)
draw & iron (walls thinner than bottom)
impact extrusion (aerosol)
66
True/False: beverage cans are made of aluminum
True (aluminum alloys)
67
What process would you use to make a 2-piece can with thin walls and a thick bottom?
draw and iron
68
describe the shallow draw process. What products usually use these can types?
feed sheet of metal in
machine presses into mold
unload -> can
shallow cans: tuna, sardines,
69
Describe the draw and redraw process
similar to shallow draw, but then RESHAPE (redraw):
metal moved from base to wall so that diameter is reduced
final product is taller thinner can
70
Describe the draw and iron process
similar to shallow draw (create shallow cup)
then push through a ring -> makes deeper cup
continue pushing through smaller and smaller rings (x3) to 'iron' walls (stretch and make longer, thinner)
base shaped by bottom die
trim top -> follow remainder of can processes
71
example of can using the draw and iron process:
soda cans
72
The wall ____ is reduced while the wall ____ is increased in the ironing process
thickness
| length
73
The main inner contents of an aerosol can:
```
propellant
liquid phase (product)
```
74
main parts of an aerosol can:
valve
dip tube (to access product)
can body
75
What can be done to prevent the product from being affected by the propellant?
placed in plastic bag
76
Examples of aerosol propellants:
NO, Ar, N2, CO2
77
What is the process of impact extrusion?
metal slug (chunk of metal) placed in die
pressed at high velocity with a punch
forces metal up and out, forming walls
(height determined by stripper plate)
78
What is the 'gauge' of aluminum foil referring to?
thickness
79
Properties of aluminum foil: (5)
```
complete barrier (thicker -> better barrier)
foldable
printable/embossable
reflective
matte/shiny
```
80
good properties of metal packaging: (5)
```
high strength to weight ratio
can be heat processed
long storage
excellent barrier/protective
prevents tampering
```
81
quality control measures of metal plates and foil (2)
thickness
| hardness
82
Quality control measures of metal cans: (8)
```
porosity of coating
side seam
double seam examination
pressure testing
vacuum testing
dye testing
axial load testing
pull tab testing
```
83
advantages of aluminum over steel: (5)
```
lighter (lower transport cost)
easier recovery/recycling
more corrosion resistant
easier opening (pull tab)
not prone to sulfide staining
```
84
advantages of aluminum beer bottles over glass: (4)
lighter
less fragile
keep beer cooler
light barrier
