Single Screw Gap Analysis - Advanced
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Single Screw Extrusion Gap Analysis - Advanced
This assessment will give you an overview of you level of knowledge in Single Screw Extrusion. You will receive an email with your result as soon as it is completed.
The assessment should take you 10-20 Minutes.
All results are strictly confidential.
Good Luck!
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Single Screw Extrusion Overview - Advanced.
Please select the best possible answer in the below questions
The effect of adding a nuclearing additive to semi-crystaline plastic is to:
Reduce the size of the crystals
Increase the percent of crystallinity
Increase crystal rate of growth
All of the above
An agent to prevent sticking of the plastic to metal surface is called a?
Nucleating agent
External lubricant
Foaming agent
Internal lubricant
Regrind:
Should be thoroughly Blended
Can affect the flow behavior of the plastic
Lowers the cost of the raw material
Should be added at a fixed percent
All of the above
If extruded plastic sheet required 2% pigment to give the desired color and the color concentrate is 50% pigment, how many pounds of color concentrate pellets are needed for each 100 pounds of virgin plastic?
Four
Eight
One
Two
Same amount
Moisture in plastics or on its surface can cause
Degradation of the plastic
Foaming
Surging in the extruder
All of the above
If biaxially oriented film is re-heated, it shrinks because:
There is no pressure on the plastic
The oriented molecules relax
The plastic degrades
All of the above
If the percentage of regrind plastic ABS being blended back in with the virgin plastic is increased the result will usually be:
A lighter part
An increase in overall viscosity of the raw material
A decrease in overall viscosity of the raw material
No affect on the overall viscosity of the raw material
Which one of these conditions causes molecular orientation
Tempreture
Pressure
Flow
Molecular weight
The temperatures of an amorphous and a semi-crystalline plastic is a fluid state are both changed the same amount. Which plastic has the greatest change in viscosity?
Semi-crystalilne
Amorphous
Both are the same
Both stay the same
If plastic raw materials is fed to the screw at a rate that does not fill the screw flight depth, it is called:
Flood feeding
Starve feeding
Surge feeding
Over feeding
In the feed zone, the temperature setting for the extruder barrel should:
Increase the friction between the plastic and the barrel
Not affect the friction between the plastic and the screw or barrel
Increase the friction between the plastic and the screw
Decrease the friction between the plastic and the barrel
The density of the plastic leaving the extruder is ________ the density of the solid plastic.
More than
Less than
The same as
Much higher than
If the level of plastic in the extruder hopper changes a great deal, it may cause:
Damage to the screw
High extruder pressure
Surging
All of the above
As the plastic travels through the feed section the plastic first begins to melt:
At the outside surface of the screw
At the inside surface of the barrel
At both the surface of the screw and barrel
About half-way between the inside barrel wall and the surface of the screw
According to the drag flow equation the output of plastic for a given screw design depends on:
Melt tempreture
melt pressure
Screw rpm
All of the above
In the barrel, where does most of the condulitive heat come from?
Front zone
Middle zone
Rear zone
None of the above
Assume you are operating an extruder and the die is readjusted to require a higher pressure. if all other operating conditions remain the same the extruder output will now:
Increase
Decrease
Stay the same
When using a melt pump, the inlet pressure to the die is controlled by
The melt pump inlet pressure
Gear pump rpm
Screw rpm
All of the above
A barrier screw is designed to:
Separate liquid from solid plastic
Seperate hotter from cooler plastic
Mix colorants into the plastic
All of the above
Cooling the Screw in the metering section:
Reduces the effective metering depth
Reduces extruder output
Both A and B
None of the above
Assume the drag flow of an extruder equals 900 lb/hr, pressure flow equals 300 lb/hr, and the leakage flow equals 50 lb/hr. What is the output of the extruder?
1250 lb/hr
750 lb/hr
550 lb/hr
1150 lb/hr
650 lb/hr
If the inlet pressure to the gear pump starts to decrease:
The gear pump rpm should be decreased
The gear pump rpm should be increased
The screw rpm should be decreased
The screw rpm should be increased
When a gear pump is used the output production line is determined by:
Sensitivity adjustment
Melt temperature
Gear pump rpm
Screw rpm
You are planning the order of run of a 3.0 melt index plastic and a 1.0 melt index plastic. For most effective changeover, which plastic should you run first.
Melt index of 3.0
Melt index of 1.0
Makes no diffrence
As a general rule, the metering zone barrel temperature should be set
To increase the temperature of the melt
To decrease the temperature of the melt
To neither increase nor decrease the temperature of the melt
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