Higher type question total marks - 23. You should be aiming to spend about 15 minutes on this question.

Often in the past, boxes such as seed trays were made from wood, but today they are usually vacuum formed from plastic.

Give two reasons why you think the change from wood to plastic has taken place.             (2 Marks)

Name a suitable plastic for making seed trays using the vacuum forming process. (1 Mark)

Wooden seed trays were about 300mm long 200mm wide and 50mm deep. Using these measurements produce a suitable design for a vacuum formed seed tray. You should make sure that you pay particular attention to the following points:

the tray must be strong enough when held by one hand at one side when it is full of wet compost (4 marks)

the tray must drain any excess water (1 Mark)

you must consider being able to transport large quantities of empty trays without taking up too much space (2 Marks)

Draw and label a cross sectional view of a former which could be used for producing a seed tray. (4 Marks)

 
Injection moulding could be used as an alternative to vacuum forming the trays and below an injection moulding machine is shown. Describe the process and what job the labelled parts do.        (6 Marks)

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If the moulding machine is used for a long time it gets hot and plastic takes a long time to cool in the mould. Describe how the mould could be cooled. (2 Marks)

Name another type of plastic forming which could be used for producing 4 metre lengths of plastic drain pipe. (1 Mark)                                   

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