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Food Packaging > Metal > Flashcards

Metal Flashcards

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Gourmet Food flashcards
1
Q

Main metals used for food packaging:

A

Aluminum

Iron

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2
Q

Mineral sources of iron (ores):

A

hematite
magnetite (highest %)
limonite
siderite

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3
Q

Ore source for aluminum:

A

Bauxite

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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%

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5
Q

Iron is usually transformed into ____ for food packaging

A

steel

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6
Q

the raw materials for steel production: (3)

A

C (Coal)
CaCO3 (limestone)
Fe2O3 (iron ore)

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7
Q

What is slag? how is it made

A

CaSiO3

made from CaO (from limestone) + SiO2

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8
Q

in making iron into steel, you need to reduce __, ___, ___, ___, and add ___, ___, ___

A

reduce Si, C, P, S

Add Mn, Ni, Cr

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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

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10
Q

What can be added to steel to increase corrosion and abrasion resistance?

A

Cr

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11
Q

What steel component will increases hardness/tensile strength, especially at high temperatures?

A

Mo

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12
Q

What is the effect of increasing Mn in steel?

A

increase strength and hardness

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13
Q

What is the effect of increasing P in steel?

A

increase strength and hardness

decrease ductility

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14
Q

What is ductility?

A

ability to be stretched into a wire

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15
Q

What is the effect of increasing Ni and Cu in steel?

A

increase toughness, tensile strength, hardness, corrosion resistance

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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)
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17
Q

What steel is used for highly corrosive products?

A

Type L

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18
Q

What steel are drawn and ironed cans made from?

A

Type D

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19
Q

What is Ni steel used for?

A

Can ends, aerosol domes

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20
Q

What is Type MR steel used for?

A

mildly/non corrosive products (low acid)

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21
Q

What is used to describe metal hardness?

A

temper

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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
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23
Q

What temper grades can be used for can bodies and ends?

A

T4 or T5

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24
Q

What are types of plating steel?

A

Electrolytic tinplate (ETP)
Chromium coated steel
Polymer coated steel

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25
Q

What is ETP?

A 
electrolytic tinplate (plated steel)
tin-iron alloy later at interface of tin/steel -> gives corrosion resistance
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26
Q

Steps for preparing ETP: (4 steps)

A

electrolytic process: bathe tin sulfate in sulfuric acid

thermal treatment (260-270C) & rapid quenching

chemical passivation in Na dichromate solution

apply oily lubricant

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27
Q

advantages (5) vs disadvantages (2) of chromium coated steel?

A

good: spontaneous passivation (thinner), cheaper, better heat resistance, coating adhesion, printing
bad: low abrasion resistance, decrease resistance to corrosion

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28
Q

What is polymer coated steel coated with? What does this achieve?

A

Polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), fluorinated perfluoroethylenepropylene (FEP)

resist abrasion, corrosion, food interactions

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29
Q

For a highly acidic food, what would be a good steel coating?

A

polymer coating (PTFE, PFA, or FEP)

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30
Q

2 processes needed to convert aluminum ore into aluminum:

A
  1. Bayer process

2. Hall heroult process

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31
Q

Requirements of the Hall Heroult process:

A

cryolite (Na3AIF6)

huge amount of energy needed

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32
Q

The bayer process converts ___ into _____

A

Bauxite

alumina

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33
Q

Aluminum can be combined with many metals such as _______, to form various ____.

A

Mn, Si, Fe, Mg, Cu, Cr

alloys

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34
Q

Magnesium in aluminum alloys will increase _____ but decrease _____

A

increase mechanical resistance

decrease corrosion resistance

35
Q

What can be added to aluminum alloys to increase corrosion resistance?

A

Mn

36
Q

List in order of increasing mass thermal capacity: Aluminum, carbon steel, stainless steel

A

stainless steel < carbon steel < aluminum

37
Q

True/False: steel has a greater thermal expansion than aluminum

A

False; aluminum has greater thermal expansion

38
Q

which is a better conductor, steel or aluminum?

A

aluminum (>carbon steel > stainless)

39
Q

true/false: aluminum has a higher melt point than steel

A

false

40
Q

which is more dense, steel or aluminum?

A

steel

41
Q

Which has a higher tensile strength, steel or aluminum?

A

steel

42
Q

2 types of cans:

A

2 piece

3 piece

43
Q

Parts of a can:

A

Top: canner’s end
Canner’s end seam
body (side seam, side wall beading)

bottom: manufacturer’s end
manufacturer’s end seam

44
Q

True/False: expansion panels are found in all metal cans

A

False: only in thermally processed cans

45
Q

What types of can body seams are there?

A

welded seam

soldered seam

46
Q

The can bottom is sealed by _____ while the top is sealed by ______

A

the maker

the canner (after filling)

47
Q

A ____ seam joins the ends to the can body

A

double

48
Q

3 piece can production steps (7 steps)

A
  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
Q

What is the purpose of beading cans?

A

strength in heat processing

50
Q

What are can flanges?

A

ridges at can body rim, for clinching with can ends

51
Q

How are side seams on cans formed, for thermally vs nonthermally processed?

A

welded electrically, laquered

clinched in non-thermally processed products

52
Q

Describe the process of electric welding for cans

A

electric resistance seam welding:

can pressed (force) between two copper electrodes (applies heat)

then coat with laquer and test integrity

53
Q

Reasons to lacquer cans? (5)

A 
improve can appearance
increase shelf life
cost reduction in steel
corrosion resistance
prevent color/flavor change in food
54
Q

requirements for can lacquers: (7)

A

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
Q

Examples of coating types for cans:

A 
acrylics
alkyds
epoxys
butadiene
phenolics
vinyls
oleoresins
56
Q

What is a can coating that has recently raised consumer concerns? Why?

A 
Bisphenol A (BPA)
synthetic estrogen activity? (endocrine disruptor); possible leaching into food
57
Q

What type of coating is fruit enamel, and what is it used for?

A

oleoresinous

dark berries/cherries that need protection against metallic salts

58
Q

What type of coating is used for corn, peas, and other sulfur-bearing products? What type is it?

A

C-enamel

Oleoresinous with suspended zinc oxide

59
Q

What is citrus enamel used for and what type of coating is it?

A

citrus products and concentrates

modified oleoresinous, polybutadienes

60
Q

What is beverage can enamel used for, and what type of coating is it?

A

veg juice, red fruit juice, corrosive fruits, non-carbonated beverages

2-coated with resinous base and vinyl top coat

61
Q

What is done in preparation of attaching the can end to the body?

A
  1. curl can end
  2. fill with sealing compound (act as gasket to help seal)
  3. flange can body
62
Q

A completed double seam on a can will be ____ layers thick at its thickest point

A

5

63
Q

The steps of double seaming (2)

A

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
Q

What materials can be used for 2-piece cans?

A

steel (type D) for thermally processed product

aluminum alloy for beverages

65
Q

Different processes to make 2 piece cans: (4)

A

shallow draw (sides < diameter)
draw & redraw (sides > diameter)
draw & iron (walls thinner than bottom)
impact extrusion (aerosol)

66
Q

True/False: beverage cans are made of aluminum

A

True (aluminum alloys)

67
Q

What process would you use to make a 2-piece can with thin walls and a thick bottom?

A

draw and iron

68
Q

describe the shallow draw process. What products usually use these can types?

A

feed sheet of metal in
machine presses into mold
unload -> can

shallow cans: tuna, sardines,

69
Q

Describe the draw and redraw process

A

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
Q

Describe the draw and iron process

A

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
Q

example of can using the draw and iron process:

A

soda cans

72
Q

The wall ____ is reduced while the wall ____ is increased in the ironing process

A

thickness

length

73
Q

The main inner contents of an aerosol can:

A 
propellant
liquid phase (product)
74
Q

main parts of an aerosol can:

A

valve
dip tube (to access product)
can body

75
Q

What can be done to prevent the product from being affected by the propellant?

A

placed in plastic bag

76
Q

Examples of aerosol propellants:

A

NO, Ar, N2, CO2

77
Q

What is the process of impact extrusion?

A

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
Q

What is the ‘gauge’ of aluminum foil referring to?

A

thickness

79
Q

Properties of aluminum foil: (5)

A 
complete barrier (thicker -> better barrier)
foldable
printable/embossable
reflective
matte/shiny
80
Q

good properties of metal packaging: (5)

A 
high strength to weight ratio
can be heat processed
long storage
excellent barrier/protective
prevents tampering
81
Q

quality control measures of metal plates and foil (2)

A

thickness

hardness

82
Q

Quality control measures of metal cans: (8)

A 
porosity of coating
side seam
double seam examination
pressure testing
vacuum testing
dye testing
axial load testing
pull tab testing
83
Q

advantages of aluminum over steel: (5)

A 
lighter (lower transport cost)
easier recovery/recycling
more corrosion resistant
easier opening (pull tab)
not prone to sulfide staining
84
Q

advantages of aluminum beer bottles over glass: (4)

A

lighter
less fragile
keep beer cooler
light barrier

Food Packaging (11 decks)

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