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| 1. What are the three principal elements
of an injection molding cycle?
A. Fill, Pack, Hold
B. Clamp, Inject, Cool
C. Fill, Cool, Release
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| 2. Barrel temperature controllers respond
to which of the condition of?
A. Plastic
B. Barrel
C. Thermocouples
D. Calibration
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| 3. Use of the front zone barrel temperature
control is for?
A. Melting plastic
B. Intensification ratio
C. Maintaining plastic temperature
D. Cooling the melt before it is injected
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| 4. The surface area of the injection
piston divided by the surface area of the screw is the
calculation for?
A. Maximum injection speed
B. Intensification ratio
C. Maximum shot size
D. Volumetric shot size
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| 5. When the machine is on cycle, the
majority of heat introduced into the plastic is a result
of?
A. Heater bands
B. Injection speed
C. Screw rotation
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6. On a hydraulic injection molding machine,
opening the rear gate should have what effect?
A. None
B. Power off
C. Pumps off
D. None of the above
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| 7. If you increase the gate diameter from
0.030" to 0.040" what would be the percent change
in the gate area?
(high - low)/original x 100
A. 10%
B. 33%
C. 50
D. 78%
E. 100%
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| 8. If a multi-cavity mold is not balanced
upon filling, balance should be achieved by?
A. Adjusting gate size
B. Polishing the runner
C. Adjusting mold temperatures
D. Profiling injection speeds
E. None of the above
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| 9. What is the projected area of a single
cavity compact disk if the diameter of the disk is 5.2
inches?
A. 21.2 square inches
B. 5.2 square inches
C. 27.0 square inches
D. 50.5 square inches
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| 10. For that same compact disk, with
an average plastic pressure in the mold of 4000 psi,
the minimum force in tons to hold the mold closed would
be?
A. 12.4 tons
B. 42.4 tons
C. 64.4 tons
D. 100 tons
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| 11. As it relates to hydraulics, Pascal's
equation states that pressure is equal to?
A. Opposing pressure
B. Surface area on which it is applied
C. Force times area
D. Force divided by area
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| 12. When displaying cycle data graphically,
the "x" (horizontal) axis typically represents?
A. Time
B. Pressure
C. Position
D. Velocity
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| 13. The process of converting monomers
(single units) into polymers is called?
A. Reaction
B. Polymerization
C. Compounding
D. Grinding
E. None of the above
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| 14. Variation in plastic material has
the greatest impact on:
A. Temperature
B. Viscosity
C. Shrinkage
D. Glass content
E. None of the above
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| 15. The length of a polymer chain affects
plastic viscosity and?
A. Temperature
B. Moisture content
C. Ability to regrind
D. Strength
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16. Which of these machine controls do
not affect plastic temperature?
A. Barrel/nozzle temperature controls
B. Back pressure
C. Screw RPM
D. They all affect plastic temperature
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17. During fill, the injection pressure
limit should be?
A. Set low enough to control injection speed
B. Set at only what is needed to fill and pack
C. Set to maximum
D. Set high enough not to be reached during normal operations
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18. If the established fill time on a four-cavity
mold is 4.0 seconds and one cavity gets blocked, what
should the new fill time be?
A. 3.0 seconds
B. 4.0 seconds
C. 5.0 seconds
D. None of the above
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19. If the gate is found to seal in 5.0
seconds, what should the hold time be set at?
A. 4 seconds
B. 5 seconds
C. 6 seconds
D. 10 seconds
E. A or C, depending on whether a sealed or unsealed gate
makes a good part
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20. What is the most common problem relative
to plastic part design?
A. Non-uniform wall thickness
B. Excessive flow length
C. Flash
D. None of the above
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21. Why is it important to have some degree
of radius on plastic parts?
A. Improve flow
B. Uniform shrinkage
C. Distribute stress
D. All of the above
E. None of the above
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22. A 4 cavity tool with a standard profit
margin of 20% is running with 1 cavity blocked - what
is the new profit?
A. Zero profit
B. +5%
C. -5%
D. -20%
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23. From a cycle time standpoint when
does cooling time actually begin?
A. At the end of fill
B. At the end of pack
C. At the end of hold
D. None of the above
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24. The heat required to melt plastic
is generated by what?
A. Heater bands (electric)
B. Screw turning (shear)
C. Equal amounts of both A & B
D. 20% from A + 80% from B
E. 20% from B + 80% from A
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25. The intensification ratio of an injection molding machine?
A. Determines the pressure amplification factor between hydraulic cylinder pressure and plastic pressure
B. Determines fill and pack pressure of plastic
C. Determines back pressure of plastic
D. Is 10:1 on all machines
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26. During first stage fill you should
set the machine to control injection ________?
A. Pressure
B. Speed
C. Time
D. None of the above
E. All of the above
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27. What information is needed to determine
the clamp force required for a given mold?
A. The total projected area of all cavities plus the runner
system at the parting line
B. The maximum average injection pressure in the cavities
C. The size of the mold
D. All of the above
E. Only A & B
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| 28. The cooling rate of plastic parts
is determined by?
A. The coolant temperature
B. The mold temperature
C. The difference in temperature between the material and the mold steel
D. the barrel temperature
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