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industrial plastics > final exam > Flashcards

final exam Flashcards

1
Q

materials + properties

What is NOT TRUE of plastics?

A

they are non-synthetic

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2
Q

materials + properties

Small molecules from which plastics are made are called _____.

A

monomers

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3
Q

materials + properties

The process by which the above molecules are combined is called _____.

A

polymerization

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4
Q

materials + properties

true or false?
A crystalline polymer structure has crystal like (orderly) regions that when heated become amorphous.

A

true

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5
Q

materials + properties

true or false?
Van der Waals forces are more electrical in nature and weaker than chemical (atomic) covalent bonds.

A

true

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6
Q

materials + properties

What molecular structure best describes a thermoset?

A

cross linked

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7
Q

materials + properties

true or false?
Amorphous polymer structure materials have a sharp melting point.

A

false

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7
Q

materials + properties

Formation of side chains of the basic polymer backbone is ____________.

A

branching

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8
Q

materials + properties

What are the advantages of using plastic?

A
  • relatively less energy to process
  • good strength to weight ratio
  • electrical insulation
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8
Q

plastics + the environment

In typical plastic product costs, about 75% of cost is attributed to…

A

material

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8
Q

plastics + the environment

true or false?
Generally plastic grocery bags are heavier than paper for a given capacity

A

false

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9
Q

plastics + the environment

The EPA suggests four methods to deal with solid waste. Which is the least desirable?

A

landfill

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9
Q

plastics + the environment

______ is the most used method of disposing of municipal solid waste in America today.

A

landfilling

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10
Q

plastics + the environment

Which of the following has the highest BTU content (potential heat energy)?

A

High Density Polyethylene (HDPE)

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11
Q

plastics + the environment

true or false?
Properly designed landfills act as a compost pit allowing biodegradable materials to return to their natural state.

A

false

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12
Q

plastics + the environment

true or false?
Thermoset plastics can easily be heated and reformed into a new shape.

A

false

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13
Q

plastics + the environment

true or false?
According to the EPA, plastics account for the biggest portion of Municipal Solid Waste by weight in the landfill

A

false

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14
Q

plastics + the environment

true or false?
Epoxy adhesives are an example of a thermoset material.

A

true

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15
Q

materials

Which plastics ARE considered to be in the polyfin family?

A
  • Polyethylene
  • Polypropylene
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15
Q

materials

This high impact polymer is often used for appliance housings and helmets.

A

Acrylonitrile Butadiene Styrene (ABS)

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16
Q

materials

This polyolefin material is often used in applications of “living” or integral hinges.

A

polypropylene

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17
Q

materials

This “slippery” material (low coefficient of friction) is often used for gears and fibers, but one drawback of this material is its high water absorption rate.

A

nylon

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18
Q

materials

This is by far the most used plastic material.

A

polyethylene

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19
Q

materials

Often “foamed” for insulation and packaging, this material is also transparent.

A

polystyrene

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20
Q

materials

Siding, gutters, wire coating, and hoses are common uses of this material.

A

Polyvinyl Chloride (PVC)

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21
Q

materials

A plastic surgeon may select this material to reshape your nose.

A

silicone

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22
Q

materials

The billiard balls and the handle on your fry pan are likely to be made of this material.

A

phenolic

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23
Q

materials

A unique thermoplastic, having extremely high heat resistance and a low coefficient of friction, originally used to coat frying pans is…

A

Polytetrafluoroethylene (PTFE)

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23
Q

casting + rotomolding

true or false?
Casting processes produce parts with little to no built in stress.

A

true

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24
Q

casting + rotomolding

true or false?
Casting is a good process to make varying shapes such as Sheets, Tubes, Rods, Tooling, Foams and other objects.

A

true

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25
Q

casting + rotomolding

Even distribution of the material to the mold surface in rotational casting is accomplished by using a…

A

biaxial rotation

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25
Q

casting + rotomolding

true or false?
One difference between a casting process and a molding process could be the amount of force that is applied to the material.

A

true

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25
Q

casting + rotomolding

In rotational molding, thermoplastic powder material joins together because it is…

A

self-fusing

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25
Q

casting + rotomolding

Casting is considered a low cost method to produce low volume parts because…

A
  • molds can be very inexpensive
  • low volume production economy
  • thermosets can be cast
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25
Q

lab + lab safety

true or false?
The PVC welding process we performed in the lab utilized a filler rod of PVC

A

true

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26
Q

casting + rotomolding

true or false?
Cast acrylic sheet can be produced by casting between panes of glass.

A

true

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26
Q

casting + rotomolding

The most used material in rotational molding is…

A

polyethylene

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26
Q

casting + rotomolding

Which of the following casting processes would be used to produce a hollow coin bank with a detailed exterior surface?

A

slush casting

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26
Q

plastics industry

Since 1980, U.S. plastics industry shipments have grown ____ percent per year.

A

3.4%

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26
Q

casting + rotomolding

Which state has the highest rotomolding plants?

A

ohio !

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26
Q

lab + lab safety

true or false?
The PVC Welding we did in the lab creates a cohesive bond of the material

A

true

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26
Q

casting + rotomolding

What is an advantage of rotational molding?

A

size range of parts

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26
Q

lab + lab safety

true or false?
You should wear safety glasses while in the plastics lab

A

true

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27
Q

casting + rotomolding

What mold material is often used for rotational molding?

A

aluminum

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27
Q

lab + lab safety

Wear what gloves when fiber glassing?

A

latex

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27
Q

casting + rotomolding

The Industrial breakdown of Rotational Molding shows that the largest percentage of products are…

A

toys

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27
Q

plastics industry

Over the past ____ years, productivity in plastics manufacturing has grown _____ percent per year, which is faster than productivity growth for manufacturuing as a whole.

A

26

2.3%

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27
Q

plastics industry

The U.S. plastics industry employs more than ____ million workers.

A

1:1

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27
Q

plastic terms + processes

What is stress?

A

amount of effort/force applied per unit area

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27
Q

plastics industry

There are nearly ____ plastics facilities in the United States.

A

18,500

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27
Q

casting + rotomolding

Rotational Molding can use which of the following form of materials?

A
  • powder
  • liquids
  • pellets
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27
Q

plastics industry

No.2 state for plastics employment?

A

ohio

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27
Q

plastics industry

Today, most paint & glues are ____ .

A

plastics

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27
Q

plastics industry

The plastics is industry the ____ largest manufacturing industry in the United States, providing significantly to the nation’s economy.

A

third

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27
Q

plastics industry

LOWEST typical plastics product costs?

A

space (1%)

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27
Q

plastics industry

The U.S. plastics industry creates $____ in annual shipments.

A

$279 billion

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27
Q

plastics industry

No.1 state for plastics employment?

A

california

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27
Q

plastics industry

What was the first thermoplastic?

A

Cellulose Nitrate (Celluloid)

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27
Q

plastic terms + processes

What is plastic?

A

pliable/deformed

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27
Q

plastics industry

What are the FOUR main characteristics or plastics?

A
  • typically organic
  • typically hydrocarbon
  • synthetic (manmade)
  • capable of being formed by heat and/or pressure
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27
Q

plastic terms + processes

What is strain?

A

deformation (change in length) to original length

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28
Q

plastics industry

Who invented the first thermoplastic and when?

A

John Hyatt in 1868

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28
Q

plastic terms + processes

What is tensile strength?

A

ability to withstand stress in tension

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28
Q

plastic terms + processes

What is elasticity?

A

ability to return to original length

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28
Q

plastic terms + processes

What is the yield point?

A

stress at which deformation starts plastically

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29
Q

plastic terms + processes

What is the modulus of elasticity?
(also called Young’s Modulus)

A

ratio of stress to strain

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30
Q

plastic terms + processes

What is compressive strength?

A

ability to withstand squeezing/pressing

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31
Q

plastic terms + processes

What is fatigue strength?

A

ability to withstand cyclic loading

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32
Q

plastic terms + processes

What is impact resistance or toughness?

A

ability to absorb impact/shocks

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33
Q

plastic terms + processes

What is flow/creep?

A

deformation upon prolonged load

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34
Q

plastic terms + processes

What is shear strength?

A

separating by tearing

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35
Q

plastic terms + processes

What is ductility?

A

ability to bend stretch or distort without failure

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36
Q

plastic terms + processes

What is hardness?

A

ability to resist scratch or dent

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37
Q

plastic chemistry

All ____ compounds are covalent bonded.

A

organic

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38
Q

plastics chemistry

Oxygen needs ____ electrons.

A

two

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39
Q

plastic chemistry

Van der Waals have the ____ bond strength.

A

weakest

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40
Q

plastic chemistry

What is metallic?

A

delocalized sharing of free electrons between a lattice of metal atoms

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41
Q

plastic chemistry

What is Ionic?

A

opposite charged ions attract (moderate strength)

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42
Q

plastic chemistry

What is Covalent?

A

gain or share electrons non metals and common in plastics (strong strength)

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43
Q

plastic chemistry

What does ‘poly’ mean in Greek?

A

many

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44
Q

plastic chemistry

What does ‘meros’ mean in Greek?

A

part or unit

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45
Q

plastic chemistry

What does ‘mono’ mean in Greek?

A

one

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46
Q

plastic chemistry

What does polymer mean?

A

many units

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47
Q

plastic chemistry

What does monomer mean?

A

one unit

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48
Q

plastic chemistry

What is polymerization?

A

combining monomers into polymers

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49
Q

plastic identification

What are thermoplastics?

A

materials that become soft when heated and solid when cooled to room temperature (can be repeated many times)

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50
Q

plastic identification

What are thermosets?

A

materials that become may be heated and formed one time

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51
Q

plastic identification

Heat reactions for thermoplastics?

A
  • similar to candle wax
  • can be heated and softened many times
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52
Q

plastic identification

Heat reactions for thermosets?

A
  • similar to concrete
  • cannot be re-softened
  • chemically cures once
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53
Q

plastic identification

What does transparent mean?

A
  • light passes thru clearly
  • may be colored
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54
Q

plastic identification

What does opaque mean?

A

no light passes thru

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54
Q

plastic identification

What does translucent mean?

A

light passes thru but is not clear

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55
Q

plastic chemistry

crystalline vs amorphous…
Which one do chemicals attack?

A

crystalline

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56
Q

plastic chemistry

What kind of order does amorphous have?

A

no order

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57
Q

plastic chemistry

What kind of order does crystalline have?

A

crystal-like orderly regions

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58
Q

plastic identification

Is Linear thermoplastic or thermoset?

A

thermoplastic

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59
Q

plastic identification

Is Cross-linked thermoplastic or thermoset?

A

thermoset

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60
Q

plastic identification

Is Branched thermoplastic or thermoset?

A

thermoplastic

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61
Q

plastic chemistry

Any branching with HDPE?

A

no

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62
Q

plastic chemistry

Any branching with MPDE/LLDPE?

A

slight

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63
Q

plastic chemistry

Any branching with LDPE?

A

long branches

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64
Q

plastic chemistry

As density increases, so does ____, ____, & ____ .

A
  • melt temperature
  • viscosity
  • strength
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65
Q

plastic chemistry

Heating/melting does not break covalent bonds, but ____.

A

weakens

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66
Q

plastic chemistry

When heat is removed, molecules
____.

A

remain in place

67
Q

plastic + the environment

What is MSW?

A

municipal solid waste
(trash or garbage)

68
Q

plastic + the environment

no. 1 material in MSW?

A

paper and paperboard (32.7%)

69
Q

plastic + the environment

Lowest waste management in America?
(landfill vs incinerate vs recycle)

A

recycle (13%)

70
Q

plastic + the environment

About how many landfills in 1988?

A

8000

71
Q

plastic + the environment

About how many landfills in 2007?

A

1700

72
Q

plastic + the environment

What percentage of waste management is discarded?

A

54%

73
Q

plastic + the environment

What percentage of waste management is combustion with energy recovery?

A

12.6%

74
Q

plastic + the environment

What is the EPA Hierarchy for integrated solid waste management?

A

1) Source Reduction
2) Recycling
3) W-T-E Incineration
4) Landfilling

75
Q

plastic + the environment

Three focuses of Source Reduction?

A

Material Replacement Creating Less Waste
Materials Engineering Using Less material
Recycling At The Source

76
Q

plastic identification

For the Plastics Coding System, what is 1?

A

polyethylene terephthalate (PET/PETE)

77
Q

plastic identification

For the Plastics Coding System, what is 2?

A

high density polyethylene (HDPE)

78
Q

plastic identification

For the Plastics Coding System, what is 3?

A

vinyl

78
Q

plastic identification

For the Plastics Coding System, what is 4?

A

low density polyethylene (LDPE)

79
Q

plastic identification

For the Plastics Coding System, what is 5?

A

polypropylene (PP)

80
Q

plastic identification

For the Plastics Coding System, what is 6?

A

polystyrene (PS)

80
Q

plastic identification

For the Plastics Coding System, what is 7?

A

other

81
Q

plastic + the environment

For recycled Coke bottles, what is the highest RPET Product Category?

A

fiber

82
Q

plastic + the environment

W-T-E Incineration reduces MSW volume by ____%

A

80-90%

83
Q

plastic + the environment

____% of U.S. MSW is incinerated

A

15

84
Q

plastic + the environment

High energy content in plastics allow “____” to be burned.

A

wet waste

84
Q

plastic + the environment

Heat can produce steam to produce electricity. This can save over ____ million barrels of
oil per year.

A

30

85
Q

plastic + the environment

What has the lowest BTU (british thermal energy) content (potential heat energy)?

A

food waste (2600 btu/lb.)

86
Q

plastic + the environment

What is the average BTU content for MSW?

A

4500 btu/lb.

87
Q

plastic + the environment

What is the #1 item in landfills?

A

paper (35%)

88
Q

plastic + the environment

What item has the lowest volume in landfills?

A

glass (2%)

88
Q

plastic + the environment

Plastics account for ____% of Natural Gas and ____% of Petroleum Consumption per year

A

7, 2

89
Q

plastic + the environment

no. 1 Natural Gas and Petroleum Consumer?

A

transportation (62%)

90
Q

plastic + the environment

What is the the myth regarding
biodegradability?

A

Properly designed landfills block out sunlight, moisture, and air which are necessary for biodegradation.

91
Q

plastic + the environment

true or false?
The Plastics Packaging Industry voluntarily stopped using fully-halogenated CFCs in 1988.

A

true

92
Q

plastic chemistry

What is branching?

A
  • Polymerization at high temp and pressure
  • Carbon-Hydrogen bond breaks, and hydrogen leaves
  • Carbon’s free radical serve as place for new chain growth
93
Q

plastic usage

What is the no. 1 usage of HDPE?

A

blow molding

93
Q

plastic usage

What is the no. 1 usage of LDPE?

A

film

94
Q

plastic usage

What was the no. 1 usage of polypropylene?

A

extrusion sheet/fiber

95
Q

plastic usage

What is the second most used plastic?

A

polyvinyl

96
Q

plastic usage

What is the no. 1 usage of PVC?

A

extrusion

96
Q

plastic usage

true or false?
Polyvinyl can breath (aka porous to oxygen)

A

true

97
Q

plastic usage

true or false?
Polyester has great solvent resistance.

A

false; it’s poor

97
Q

plastic usage

What is the no. 1 usage of PET?

A

blow molding

98
Q

plastic usage

What is the no. 1 usage of polystyrene?

A

extrusion

98
Q

plastic usage

ABS is about ____% higher than the cost of polystyrene

A

20%

99
Q

plastic usage

What is the no. 1 usage of phenolics?

A

bond plywood

100
Q

plastic usage

true or false?
A common usage of phenolic is pool billiard balls.

A

true #loveballs

101
Q

plastic usage

What is the hardest plastic?

A

melemine

102
Q

plastic usage

What is the no. 1 usage of polyurethane?

A

flexible foam

103
Q

casting + rotomolding

Biaxial rotation has rotations from ____ to
____ rpm

A

7 to 20

103
Q

casting + rotomolding

Name some advantages of rotational molding.

A
  • Seamless hollow parts
  • Size Range of parts
  • Multiple & varied parts
  • Nearly stress-free parts
  • Complexity of shapes
  • Inexpensive tooling
  • Consolidation of parts
  • Decorating possibilities
  • Time to market
103
Q

casting + rotomolding

What is the four-step process of rotational molding?

A

1) Load Material
2) Heating Phase
3) Cooling Phase
4) Unload Product

104
Q

casting + rotomolding

Name some disadvantages of rotational molding.

A
  • Single sided surface detail
  • Wall thickness variation
  • Long heat cycles
  • Mold & material must be cooled
  • Limited materials
  • self fusing
  • Material prep cost (pulverizing)
  • Shrinkage = warp, twist, dimensional problems
104
Q

casting + rotomolding

How many arms do individual-arm style?

A

1-arm to 4-arms

105
Q

casting + rotomolding

What is the lowest usage of rotationally molded plastics?

A

playground equipment (2.3%)

106
Q

casting + rotomolding

What is the lowest typical plastic material used?

A

Fluorocarbons (0.1%)

107
Q

casting + rotomolding

Name the five examples of molding/casting materials.

A
  • Cast Aluminum
  • Fabricated Aluminum
  • Machined Aluminum
  • Fabricated Mild Steel
  • Fabricated Stainless Steel
108
Q

casting + rotomolding

What is cast aluminum produced from?

A

pattern (?)

108
Q

casting + rotomolding

What is fabricated aluminium fabricated from?

A

sheet stock

109
Q

plastic terms + processes

What are monomers?

A

liquid resin thermosets

110
Q

plastic terms + processes

What are modified monomers?

A

partially polymerized sort chain polymers, TP or TS

111
Q

casting + rotomolding

What are ways to dip-cast?

A

1) Heat dip
2) Cool (cure)
3) Strip/remove

111
Q

plastic terms + processes

What are powders?

A

fully polymerized thermoplastics

111
Q

plastic terms + processes

What are plastisols?

A

solvent solutions of plastics

112
Q

plastic identification

what are trash bags made out of?

A
113
Q

plastic identification

what is fishing line made out of?

A

nylon

114
Q

plastic identification

what is the boeing 747 made out of?

A
114
Q

plastic identification

what is an intergral hinge made out of?

A

polypropelene

115
Q

plastic identification

what is a cordless drill made out of?

A

ABS

116
Q

plastic properties

what temperature can crystalline thermoplastic sheets can handle (softened, reshaped, cooled)?

A

2 - 5° F

117
Q

plastic properties

what temperature can amorphous thermoplastic sheets can handle (softened, reshaped, cooled)?

A

80 - 100° F

118
Q

thermoforming

what issues come with thermoforming?

A
  • sheet thickness
  • size limits
118
Q

thermoforming

advantages of thermoforming?

A
  • low machine costs
  • low temperature
  • low mold cost
  • low pressure
  • large parts
  • fairly fast cycles
119
Q

plastic + the industry

packaging is ____ % of the market

A

75%

120
Q

thermoforming

disadvantages of thermoforming?

A
  • high raw material $
  • high scrap (trim)
  • limits part geometry
  • only one “good” side
  • wall thickness variation
121
Q

thermoforming

materials used in thermoforming?

A
  1. polystyrene
  2. ABS
  3. PVC
  4. Acrylic
  5. HCPE
  6. Polypropylene (fast growing)
  7. Celluosics (decreasing)
  8. LDPE (no growth)
  9. PET (rapidly growing)
122
Q

thermoforming

A

aluminum

122
Q

thermoforming

name thermoforming forces applied to sheets

A

mechanical (matched die forming)
air (pressure forming)
vaccum (straight vaccum forming)
any combination (drape, plug assist)

123
Q

thermoforming

most expensive/complex tooling?

A

stainless steel

124
Q

thermoforming

lowest cost tooling?

A

plaster

125
Q

thermoforming

What Drives Tool Material Selection?

A

the workpiece matieral being machined; best performance in wear resistance, cutting, and heat

126
Q

thermoforming

what’s the thing with drape/plug?

A

mechanical stretch then vaccum

126
Q

thermoforming

what is the three and four stage process? (on the heavy gauge sheet)

A

heating -> forming -> load/unload -> pre-heat

127
Q

thermoforming

what’s the problem with straight vaccum (cavity)?

A

limited force; only one good side

128
Q

thermoforming

what’s with straight mechanical?

A

high mold cost + high force

129
Q

thermoforming

what’s the thing with straight pressure?

A

high force

130
Q

thermoforming

what’s with plug assist?

A

clamp frame + vaccum on

131
Q

thermoforming

what’s the difference between cavity vs plug?

A

last point to draw = thinnest

132
Q

thermoforming

what’s with snap back?

A

vaccum draws down, prestretch then vaccum draws up

133
Q

composites

what are composites?

A

a material made up of two or more different material components
* to obtain specific characteristics and properties
with the primary goal of increasing mechanical
strengths.

134
Q

composites

what two components make a composite?

A

a reinforcing element
a compatible resin binder

135
Q

composites

what’s the highest composite in the industry?

A

transport (32%)

136
Q

composites

what’s the lowest composite in the industry?

A

aircraft (1%)

137
Q

composites

how much growth has U.S composites averaged since 1960?

A

6.5%

138
Q

composites

since 1960, steel has nearly ____ , GDP has ____ , aluminum has ____ , and composities have grown ____ times

A

doubled, tripled, quadrupled, 16

139
Q

composites

advantages of composites?

A
  • strength to weight ratios
  • durability
  • cosmetics
  • impact toughness
  • corrosion resistance
  • part count reduction
  • complex shapes possible
140
Q

composites

disadvantages of composites?

A

cost!

for materials, processes, finishing, repair, etc.

141
Q

composites

when reinforcing materials,

ingredients added to polymers that ____ , thus creating a composite for the purpose of ____ physical properties.

A

do NOT dissolve, increasing

142
Q

composites

what are the effects of reinforcement?

Å

A
  • length and concentration of reinforcement major factors that affect properties of resin
  • more significant starting at 4 inches and 40%
  • fiber mechanical properties starts dominating
  • resin becomes supportinf role to give the part a shape and protect the fibers
  • i.e 60% carbon fiber loading on epoxy could increase the tensile strength from 8000 psi to 130k psi
143
Q

composites

how to compare strengths?

A
  • strength divided by specific gravity
  • modulas divided by specific gravity
144
Q

composites

what 3 types of reinforcements dominate the industry?

A
  • fiberglass
  • aramia (kevlar)
  • carbon (includes graphite)
145
Q

composites

what are two advance composites?

A

carbon fiber and aramid fiber (kevlar)

146
Q

composites

why is carbon fiber and aramid fiber advanced composites?

A

limited due to cost

147
Q

composites

highest globally advanced composite used?

A

civil aircraft interiors (18%)

148
Q

composites

what’s the lowest globally advanced composite?

A

tooling (2%)

149
Q

composites

what temperature does fiberglass melt?

A

2500 - 3000° F

150
Q

composites

what forms of fiberglass are there?

A

fiber/filament, strand/tow, roving/yarn, weaves, chopped strand, and mat

151
Q

composites

how thin is fiber?

A

0.0002 - 0.001 in

152
Q

composites

how many fibers is in a strand?

A

300 - 1000 fibers

153
Q

composites

what are the glass fiber forms?

A
  • roving (long continuous strands)
  • woven roving (woven strands)
  • cloth (woven fine strands)
  • chopped strands (1/8” - 2”)
  • mat (chopped strands held with binder, typically 1.5 - 2.5”)
  • continous strand mat (swirled onto a belt; for compression and rotation molding)
  • milled fiber (under 1/8” chopped)
154
Q

composites

what are the orientations of fiberglass?

A
  • unidirectional (arrows in one parallel direction)
  • bidirection (arrows in perpendicular direction)
  • random (arrows everywhere and diagonal too)
155
Q

composites

what are the types of glass fibers?

A
  • electrial (electrical)
  • chemical (chem resistance)
  • strength (higher strength than electrical)
156
Q

composites

can polymers be reinforced?

A

yes

157
Q

composites

reasons why epoxy can be a reinforcement?

A
  • more expensice
  • less required
  • superior adhesion
  • sensitivity
158
Q

composites

reasons why polyester can be a reinforcement?

A
  • air-inhibited (cured, layered)
  • thixotropic (shear thinning) fillers
  • polymerization
  • catalyst (initiators)
  • accelerators (promoters)
  • methyl ethyl ketone peroxide
  • radiation / u.v / heat
159
Q

composites

what types of materials can be made into molds?

A
  • plaster
  • wood
  • reinforced polyester
  • reinforced epoxy
  • aluminum
  • steel
160
Q

composites

molds must be ____

A

nonporus (doesn’t let liquid and air in)

161
Q

composites

what are the types of mold releases?

A
  • high gloss surface
  • high carnuba content wax
  • silicone
  • polyvinyl alcohol film
162
Q

composites

what are the mold processes?

A
  • hand lay-up
  • spray up
  • vaccum bag
  • matched die
  • filament winding
  • pultrusion
  • resin transfer molding
163
Q

composites

what processes are open mold?

A
  • hand lay-up
  • spray up
  • vaccum bag
164
Q

composites

what is the highest molding process by distribution?

A

open molding (47%)

165
Q

composites

what’s the lowest molding process by distribution?

A

pultrusion (5%)

166
Q

composites

what does the process selection depend upon?

A
  • resin type
  • product’s size/shape
  • loading %
  • orientation
  • form/length
167
Q

composites

what does gel coating do?

A

it creates the outer surface on a product

168
Q

composites

with resin transfer molding, the reinforcement is ____ placed in a mold which is closed

A

strategically

169
Q

cellular plastics

characterizations of foam?

A
  • cell structure
  • stiffness
  • density
170
Q

cellular plastics

what is an open celled structure?

A

cells are interconnected and can’t hold gasses; water + air pass through

171
Q

cellular plastics

what are the applications for open celled structures?

A
  • sponges
  • air filters
  • sound insulation
  • cushioning
171
Q

cellular plastics

what are the applications for closed celled structures?

A
  • shoe soles
  • thermal insulation
  • floatation
  • cushioning
171
Q

cellular plastics

examples of flexible foam?

A
  • shoe soles
  • wrestling mats
  • cushioning
171
Q

cellular plastics

what is a closed cell structure?

A

cells are seperate like tiny balloons and are not interconnected. water + air don’t pass through

171
Q
A
172
Q

cellular plastics

examples of rigid foam?

A
  • “bead-board” insulation
  • structrual parts
172
Q

injection molding key process steps include mold close, inject material, hold, plasticize next shot, mold open

A

true

172
Q

The purpose of a venting system in injection molding is to allow air to exit the mold cavity as the molten plastic comes in

A

true

172
Q
A
172
Q
A
172
Q

the junction between the runner system and the cavity in an injection mold is normally bridged by a ____ which increases material velocity as well as facilitates part removal from the runner system

A

gate

172
Q
A
172
Q
A
172
Q
A
173
Q

In a reciprocating screw injection molding machine the screw arguers the material into the mold using the flutes on the screw

A

false

173
Q
A
173
Q

Injection molding runner systems deliver material from sprue to the runners then the gates and parts

A

true

173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
173
Q
A
174
Q
A

industrial plastics (1 decks)

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