Fig. 3 shows the vacuum forming process. The item shown is commonly used in design and technology projects. It has been designed and manufactured to meet sp...

(a) Name the parts labelled A and B [2]

1. A - Heater element / radiant heater [1]. This provides the heat source positioned above the thermoplastic sheet to soften it before forming.
2. B - Thermoplastic sheet / clamped plastic sheet [1]. This is the material that will be heated and then drawn over the mould by the vacuum.

(b) Describe the stages of the vacuum forming process [4]

1. The thermoplastic sheet is clamped securely in the frame above the platen [1].
2. The heater is positioned above the sheet and heats it until it becomes soft and pliable (it will visibly sag when ready) [1].
3. The mould is raised up into the softened sheet. Air is then sucked out through the small holes in the platen by the vacuum pump, creating a pressure difference that forces the plastic tightly over every surface of the mould [1].
4. The plastic is allowed to cool and harden around the mould. It is then removed from the frame, separated from the mould, and any excess material is trimmed away [1].

(c) Give one advantage and one disadvantage of vacuum forming compared to injection moulding [2]

Advantage (any one for [1]):

• Lower tooling cost / cheaper moulds - vacuum forming moulds can be made from wood or resin rather than expensive hardened steel.
• More suitable for one-off or batch production runs where high initial investment in tooling is not justified.

Disadvantage (any one for [1]):

• Only produces simple, open (single-sided) shapes - complex enclosed forms with undercuts cannot be made.
• Uneven wall thickness / thinning at corners and deep draws - the material stretches thinner where it has to travel furthest over the mould.
• Slower for mass production - cycle times are longer and each piece needs trimming, making it less efficient at very high volumes.