Extruder

Question 1

the equipment used to convert the solid plastic, usually in pellet form, into a melt.

Answer 1

extruder

Question 2

is used for film and sheet, and is part of a blow molder for bottles.

Answer 2

extruder

Question 3

is the granulated scrap from the conversion process

Answer 3

regrind

Question 4

the screw if generally divided into three sections:

Answer 4

1. the solids conveying section
2. the compression or melting section
3. the metering or pumping section

Question 5

are usually circular in cross section, to avoid stagnant areas in the flow path

Answer 5

hoppers

Question 6

a too-rapid decrease in diameter of the hopper can cause

Answer 6

bridging

Question 7

hoppers can also be equipped with ______ to help in forcing plastic material into the throat of the extruder

Answer 7

augers

Question 8

is often provided at the hopper and feed port, to prevent premature melting of the plastic, which can create blockages that interfere with a consistent rate of flow of the plastic into the extruder

Answer 8

cooling

Question 9

responsible for conveying the plastic forward in the extruder

Answer 9

friction between the plastic and the barrel

Question 10

This is the part of the extruder that determines the shape of the molten polymer as it exits the machine.

Answer 10

Die

Question 11

True or False. The channel depth ratio in the feed section is greater than that in the metering section of the extruder.

Answer 11

True

Question 12

True or False. Inside the barrel, the pellets should slip on the screw surface and stick to the inside barrel surface in order to be conveyed forward.

Answer 12

True

Question 13

What do you call the machine that melts the polymer resins?

Answer 13

Extruder

Question 14

True or False. Extruders by design can only have one hopper.

Answer 14

False

Question 15

This is the part of the extruder that filters the molten polymer coming out.

Answer 15

Breaker Plate/Screen Pack

Question 16

This is the body of the extruder which contains the screw.

Answer 16

Barrel

Question 17

Which section in the extruder does the actual melting of the pellets take place?

Answer 17

Transition

Question 18

This is the part of the extruder where pellets are placed.

Answer 18

Hopper

Question 19

An extruder has the specs of 24:1. What does this mean?

Answer 19

The screw length is 24 times the barrel diameter

Question 20

This part of the screw is responsible for delivering molten polymer at a desired and uniform rate to the shaping device.

Answer 20

metering section

Question 21

The ratio of the depth of the channels in the feed section to the depth of the channels in the metering section

Answer 21

channel depth ratio

Question 22

main function of the compression section of the screw

Answer 22

melting of the plastic

Question 23

function to create back-flow and increased shearing to aid in the dispersion of the nonuniformity, and are typically located within the metering section of just after it

Answer 23

mixing devices

Question 24

variety of mixing devices

Answer 24

pin, pineapple, Maddock and Dulmage designs

Question 25

Extruder output is proportional to

Answer 25

the cube of the inside diameter of the barrel.

Question 26

The ratio of the depth of the channels in the feed section to the depth of the channels in the metering section, called the

Answer 26

channel depth ratio

Question 27

.Dies generally have at least _____ temperature control zone, independent of the extruder temperature settings, and may have several

Answer 27

one

Question 28

Extruders generally contain _____ for filtering impurities out of the melt

Answer 28

screens

Question 29

The amount of power required is affected by

Answer 29

the viscosity (resistance to flow) of the polymer and the back pressure generated by the die.

Question 30

In this type of extruder, a vacuum is applied to the melt through a specially designed vent port on the side of the barrel

Answer 30

vented extruder

Question 31

contain two screws. -they can mix components much more effectively than single screw extruders, they are often used for mixing operations such as compounding in additives to make concentrates of color, antioxidant, etc.

Answer 31

Twin screw extruders

Question 32

A rough guideline for crystalline plastics is to process them at about _____ above their melting point

Answer 32

50°C

Question 33

For amorphous plastics, processing at ______ above the glass transition temperature provides a rough guideline.

Answer 33

100°C

Question 34

Plastics which are ______ should be processed at lower temperatures

Answer 34

heat-sensitive

Question 35

_____ plastics should be processed at higher temperatures

Answer 35

highly viscous

Question 36

usually consists of a rupture disk or a shear pin in the clamp which holds the die against the barrel of the extruder, as well as with an automatic shutoff if the pressure reaches a critical value

Answer 36

over-pressure safety device

Question 37

materials with thickness of 0.003 in or less are considered

Answer 37

film

Question 38

materials with thickness of ____ in or greater are considered sheet

Answer 38

0.010

Question 39

is generally produced by downward extrusion

Answer 39

cast film

Question 40

is typically used to pin the plastic against the first chill roll

Answer 40

air knife

Question 41

can also be used to produce film and sheet with desired thicknesses and surface textures

Answer 41

calendering

Question 42

In this process, the polymer melt is squeezed between pairs of co-rotating high precision rollers, followed by a series of chilling rolls.

Answer 42

calendering

Question 43

For some operations, the chill roll method does not provide rapid enough cooling. In that case, ________ may be used for cooling and solidifying the plastic

Answer 43

a water-filled quench tank

Question 44

There are two major approaches to minimizing the problem of gauge bands

Answer 44

1. The oldest method is oscillating the film as it is wound, to produce some randomization of the thickness variations. 2. The more modern approach uses sensors to monitor the thickness of the web on-line, using a scanning measuring head that travels across the film so that thickness can be measured along both the length and the width dimensions.

Question 45

_____ ,stretching the film to produce some molecular realignment in the direction of the stretch, is often used to modify cast film properties

Answer 45

orientation

Question 46

The film is referred to as “_____” if the orientation is equal in the two directions

Answer 46

balanced

Question 47

The film is referred to as “_____” if it is more highly oriented in one direction than in the other

Answer 47

unbalanced

Question 48

A crystalline polymer must be oriented at a temperature _______, but high enough to provide some mobility to the molecules

Answer 48

below its melt temperature

Question 49

the main components of a die include

Answer 49

inlet channel, manifold, approach or land, die lips

Question 50

delivers the plastic from the extruder to the die

Answer 50

inlet channel

Question 51

is designed to evenly distribute the melt within the die

Answer 51

manifold

Question 52

carries the melt from the manifold to the die opening

Answer 52

approach or land

Question 53

perform the final shaping of the melt as it exits the die

Answer 53

die lips

Question 54

for cast film or sheet, the die opening is ______, producing a thin, wide exiting stream of plastic

Answer 54

slit-shaped

Question 55

The most common die configuration for production of cast film and sheet is

Answer 55

coat-hanger die

Question 56

is a continuous process in which the polymer is melted, the melt is forced through an annular die, and the resulting tube is inflated with air into a “bubble” and cooled

Answer 56

blown film extrusion

Question 57

The principal polymers used in blown film production are

Answer 57

polyolefins

Question 58

The properties of the film are determined by

Answer 58

the blow-up ratio and the speed

Question 59

is the ratio between the diameter of the final tube of film and that of the die

Answer 59

blow-up ratio

Question 60

involves the extrusion and blowing of a tube of molten plastic in a downward direction

Answer 60

double bubble process

Question 61

the double bubble process is most often applied to

Answer 61

PP film

Question 62

introduced a triple-bubble process

Answer 62

Kuhne GmbH

Question 63

uses infrared heat, rod heaters, and other annealing techniques in a "thermofixation" station to impart precise shrink rates to coextruded film

Answer 63

triple-bubble process