VACUUM FORMING

WHAT IS IT?

• Process for forming sheet thermoplastics.
• Plastic is heated then sucked over a former using a vacuum.
• The thermoplastic is left to cool and then removed.
• The formed plastic mirrors the shape of the former.
• http://youtu.be/DnYMbExC_oE

STAGES OF MANUFACTURE
1. Produce high quality former of exact shape of item to be formed.
Sides of former must be tapered and have no undercut elements, so formed product can be easily removed.
Very small holes should be drilled through former so air can be sucked through.
2. Former is placed in machine and sheet of thermoplastic is clamped into place above it.
Heat plastic till it is soft and pliable.
3. Former is raised into plastic and air is sucked out.
Atmospheric pressure forces plastic around former thus taking on its shape.
4. Plastic cools and is removed.

APPLICATIONS

• Yoghurt pots
• Blister packs
• Insides of fridges
• Chocolate selection box interiors
• Packaging

POLYMERS USED

• Most thermoplastics can be used. Commonly used:
• Acrylic (polymethyl methacrylate)
• HIPS (High impact polystyrene)
• PVC (polyvinyl chloride)
• [MDF (medium density fibreboard) is usually used for former.]

ADVANTAGES/ DISADVANTAGES

• Ideal for batch production.
• Inexpensive
• Relatively easy to make moulds that can be modified
• BUT, mould must be accurate to prevent webbing
• Large amounts of waste materials produced