Question 1

The parting line in injection molding is which one of the following:

Accepted Answer

A)  the lines formed where polymer melt meets after flowing around a core in the mold
B)  the narrow gate sections where the parts are separated from the runner
C)  where the clamping unit is joined to the injection unit in the molding machine
D)  where the two mold halves come together D

Question 2

The die swell ratio for a polymer melt has a value that is never less than one:

Accepted Answer

A) True 
 B)False  True

Question 3

Reaction injection molding is used for which one of the following plastic types:

Accepted Answer

A)  thermoplastics
B)  thermosets B

Question 4

Extrusion is a compression process in which material is forced to flow through a die orifice to provide long continuous product whose cross-sectional shape is determined by the shape of the orifice:

Accepted Answer

A) True 
 B)False

Question 5

In rotational molding, centrifugal force is used to force the polymer melt against the surfaces of the mold cavity where solidification occurs:

Accepted Answer

A) True 
 B)False

Question 6

Which of the following are sections of a conventional extruder barrel for thermoplastics (three correct answers):

Accepted Answer

A)  compression section
B)  die section
C)  feed section
D)  heating section
E)  metering sectionF) shaping section

Question 7

Thermoforming is limited to which one of the following plastic types:

Accepted Answer

A)  elastomers
B)  thermoplastics
C)  thermosets

Question 8

A three-plate mold offers which of the following advantages when compared to a two-plate mold (two best answers):

Accepted Answer

A)  automatic separation of parts from runners
B)  gating is usually at the base of the part to reduce weld lines
C)  sprue does not solidify
D)  stronger molded parts

Question 9

The forward movement of polymer melt in an extruder barrel is resisted by drag flow, which is caused by the resistance to flow through the die orifice:

Accepted Answer

A) True 
 B)False

Question 10

Which of the following defects are associated with injection molding (three correct answers):

Accepted Answer

A)  bambooing
B)  die swell
C)  drag flow
D)  flash
E)  melt fractureF) short shotsG) sink marks

Question 11

Bambooing is a more severe case of which one of the following defects in plastic extrusion:

Accepted Answer

A)  melt fracture
B)  sharkskin
C)  viscoelasticity

Question 12

Injection molding is a process in which a polymer is heated to a highly plastic state and forced to flow under high pressure into a mold cavity, where it solidifies and is then removed from the cavity:

Accepted Answer

A) True 
 B)False

Question 13

Use of a parison is associated with which one of the following plastic shaping processes:

Accepted Answer

A)  bi-injection molding
B)  blow molding
C)  compression molding
D)  pressure thermoforming
E)  sandwich molding

Question 14

The principal components of an injection molding machine are which two of the following:

Accepted Answer

A)  clamping unit
B)  hopper
C)  injection unit
D)  mold
E)  part ejection unit

Question 15

Compression molding and transfer molding can be used on both thermosets and elastomers:

Accepted Answer

A) True 
 B)False

Question 16

The function of the ejection system in injection molding is which one of the following:

Accepted Answer

A)  move polymer melt into the mold cavity
B)  open the mold halves after the cavity is filled
C)  remove the molded parts from the runner system after molding
D)  separate the part from the mold cavity after molding

Question 17

Compression molding differs from injection molding in which of the following respects (two correct answers):

Accepted Answer

A)  faster production rates
B)  molds are simpler
C)  part geometries are generally more complex
D)  presses are oriented vertically rather than horizontally
E)  shorter cycle times

Question 18

The term encapsulation refers to which one of the following plastics shaping processes:

Accepted Answer

A)  casting
B)  compression molding
C)  extrusion of hollow forms
D)  injection molding in which a metal insert is encased in the molded part
E)  vacuum thermoforming using a positive mold

Question 19

In which of the following properties do plastic parts often compare favorably with metals (two best answers):

Accepted Answer

A)  impact resistance
B)  resistance to ultraviolet radiation
C)  stiffness
D)  strength
E)  strength-to-weight ratioF) temperature resistance

Question 20

A thermoforming mold with a convex form is called which one of the following:

Accepted Answer

A)  a die
B)  a negative mold
C)  a positive mold
D)  a three-plate mold

Exam 10: Shaping Processes for Plastics

The parting line in injection molding is which one of the following:

The die swell ratio for a polymer melt has a value that is never less than one:

Reaction injection molding is used for which one of the following plastic types:

Extrusion is a compression process in which material is forced to flow through a die orifice to provide long continuous product whose cross-sectional shape is determined by the shape of the orifice:

In rotational molding, centrifugal force is used to force the polymer melt against the surfaces of the mold cavity where solidification occurs:

Which of the following are sections of a conventional extruder barrel for thermoplastics (three correct answers) :

Thermoforming is limited to which one of the following plastic types:

A three-plate mold offers which of the following advantages when compared to a two-plate mold (two best answers) :

The forward movement of polymer melt in an extruder barrel is resisted by drag flow, which is caused by the resistance to flow through the die orifice:

Which of the following defects are associated with injection molding (three correct answers) :

Bambooing is a more severe case of which one of the following defects in plastic extrusion:

Injection molding is a process in which a polymer is heated to a highly plastic state and forced to flow under high pressure into a mold cavity, where it solidifies and is then removed from the cavity:

Use of a parison is associated with which one of the following plastic shaping processes:

The principal components of an injection molding machine are which two of the following:

Compression molding and transfer molding can be used on both thermosets and elastomers:

The function of the ejection system in injection molding is which one of the following:

Compression molding differs from injection molding in which of the following respects (two correct answers) :

The term encapsulation refers to which one of the following plastics shaping processes:

In which of the following properties do plastic parts often compare favorably with metals (two best answers) :

A thermoforming mold with a convex form is called which one of the following: