Injection Unit Functions

Question 0

What are the clamp unit functions?

Answer 0

Opens mold
Closes mold
Safety interlock
Ejects parts
Mold hight
Core movement

Question 1

What are the main injection unit functions?

Answer 1

Causes plastic to flow
Pressurizes the plastic
Holds nozzle against sprue bushing
Turns the screw
Regulates back psi
Decompresses the melt

Question 2

What are the 4 basic mechanical elements?

Answer 2

Tank
Pumps
Valves
Actuators

Question 3

The 3 basic hydraulic principles?

Answer 3

Movement is caused by oil flow
Rate of oil flow determines speed
Resistance to oil flow determines psi

Movement:oil flow controlled
Force or psi:psi controlled

Question 4

What Are the three main feedstocks or sources?

Answer 4

Petroleum
Natural gas
Agriculture

Question 5

What is a monomer?

Answer 5

One

Question 6

What is a polymen?

Answer 6

Many

Question 7

What is a thermalplastic?

Answer 7

It is materials pliable with heat

Question 8

What is a thermoset?

Answer 8

Set with heat

Question 9

What is a homopolymer?

Answer 9

A polymer is formed by the polymerization of a single monomer

Question 10

What is a copolymer?

Answer 10

A polymer formed by the polymerization of a single monomer

Question 11

What is a blend?

Answer 11

A blend is two or more homopolymers are mixed together after polymerization

Question 12

What are types of degration?

Answer 12

Thermal and chemical

Question 13

What are additives that are used to fine tune a polymers properties?

Answer 13

Colorants
Release agents 
Anti-static agents
Blowing agent
Flame retardents
Stabilizers

Question 14

Define regrind

Answer 14

Plastic that has been processed one or more times

Question 15

What are three types of polymer morphology?

Answer 15

Amorphous
Crystalline
Oriented

Question 16

What is the structure in witch the polymer chains lie very close to one another and are able to chain form?

Answer 16

Crystalline

Question 17

What is the structure of polymer chains in witch the chains are randomly distributed?

Answer 17

Amorphous

Question 18

What is the structure in witch the polymer chains are lined up in a preferred direction?

Answer 18

Oriented

Question 19

What dose Tg mean?

Answer 19

Glass transition temp

Question 20

Define viscosity

Answer 20

Viscosity is the resistance to flow

Question 21

A material with high viscosity means what?

Answer 21

High resistance to flow (pushes hard)

Question 22

A material with a low viscosity means what?

Answer 22

Low resistance to flow (pushes harder)

Question 23

The 4 primary plastic processing conditions are:

Answer 23

Plastic temp
Plastic flow rate
Plastic psi
Plastic cooling rate

Question 24

What are the four things that have direct impact on the plastic temp?

Answer 24

Screw type
Mixing section
Compression ratio
L/D ratio

Question 25

Approximently 20/30% of the heat comes from?

Answer 25

Barrel

Question 26

Approximately 70/80% of the heat comes from?

Answer 26

Screw speed/ RPM

Question 27

What is a good starting point for back pressure?

Answer 27

500-1000psi

Question 28

What are the overall effects of plastic flow rate?

Answer 28

Viscosity reduction
Molecular orientation
Internal heat

Question 29

What is VPT?

Answer 29

Velocity to pressure transfer

Question 30

5ways to change VPT?

Answer 30

Hydraulic psi
Injection time
Screw position
Cavity psi
Cavity temp

Question 31

Cooling rate affects what?

Answer 31

Warpage
Shrink
Degree of crystalline
Retained molecular orientation

Question 32

Slow cooling rate =

Answer 32

High mold temp

Question 33

Fast cooling rate =

Answer 33

Low mold temp