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1. When purging an injection moulding machine cylinder, the following conditions should be used… *
a)High pressure and fast speed
b)Higher temperature and slow speed
c)Low pressure and slow speed
d)Existing speed and pressure

2. If the nozzle or purge guard is lifted away from its closed position, the machine must not allow…
a)Operation of ejectors
b)Advance of the carriage or purging
c)Closing of the mould
d)Operation of cores

3. It is important to check the SWL when…
a)Establishing component quality
b)Lifting a mould during a change-over
c)When selecting material for a production run
d)When deciding how to clamp a mould to the platen

4. The British Plastics Federation (BPF) code of practice states that guards must be checked…
a)Monthly
b)Daily
c)When mould is changed
d)All of the above

5. When setting the clamping end of an injection moulding machine, at what point should mould protection pressure be introduced?
a)Just before the mould faces meet
b)Before guide dowels enter their bushes
c)Before initiating final slow close speed
d)When mould faces are in contact

6. On a multi-impression cold runner mould, the runners and gates should ideally be…
a)As large as possible
b)Circular
c)Balanced to provide even filling
d)Vented as near as possible to the sprue

7. What causes the screw to move backwards during plasticisation?
a)Rotation of the screw motor
b)Hydraulic pressure behind the piston
c)Pressurisation of material in front of the screw
d)Back pressure

8. To prevent material backflow within the barrel, injection moulding machine screws are fitted with…
a)A metering zone
b)A check ring
c)A smear head
d)A large root diameter

9. Thermocouples are used to…
a)measure pressure
b)measure speed
c)measure temperature
d)control temperature

10. If a piece of cardboard is crushed when checking mould safety, which of the following may require adjustment?
a)Tonnage
b)Mould safety time
c)Clamp lock up position
d)Cooling time

11. A hand held pyrometer could be used to obtain…
a)hydraulic pressure readings
b)mould and melt temperatures
c)voltage readings
d)water flow readings

12. If adequate venting is not provided within a mould, which of the following moulding problems is likely to occur?
a)Stressed mouldings
b)Gas traps or burns
c)Mouldings failing to eject
d)Ejector pin marks

13. During production it is discovered that components are undersize to the specification. Which of the following could be the probable cause?
a)No melt cushion
b)Hold time too low
c)Holding pressure too low
d)All of the above

14. Jetting may be improved by…..
a)Reducing injection speed
b)Increasing first stage pressure
c)Reducing holding pressure
d)Increasing cooling time

15. A weld line is….
a)where melt fronts have met
b)where two components have been joined
c)a mark from the construction of the mould cavity
d)a mark from the parting line of the mould

16. Delamination can be caused by…
a)Excessive holding pressure
b)Mould temperature too high
c)Injection pressure too low
d)Processing mixed materials

17. Which of the following faults may occur when changing to a grade of material with a higher MFI?
a)Shorts
b)Weld lines
c)Delamination
d)Flash

18. Which of the following materials will not soften when reheated after moulding?
a)Polystyrene
b)Thermosetting polyester
c)Acetal
d)Thermoplastic elastomer

19. Complete the following statement. “Semi crystalline plastics melt……
a)at low temperatures
b)gradually over a wide temperature range
c)at high temperatures
d)over a narrow temperature range

20. Which of the following statements is correct regarding the shrinkage of the different types of thermoplastics when injection moulding?
a)All thermoplastics shrink by similar amounts
b)Amorphous thermoplastics generally shrink more than semi crystalline materials
c)Shrinkage of thermoplastics is negligible
d)Shrinkage of semi crystalline plastics is about twice that of amorphous plastics