The vacuum forming process involves heating a plastic sheet with hot air until soft, draping it over a mold, and using vacuum suction to form the sheet tightly to the mold. Common plastics used are polystyrene, polyethylene, polyvinyl chloride, and acrylic. Vacuum forming allows for low-cost production of prototypes and small runs due to inexpensive equipment and fast mold making. However, additional trimming is usually required and high-volume production requires more complex machinery.
2. The Vacuum Forming Process
1. The process involves heating a plastic
sheet until soft.
2. The softened sheet is draped over a
mould.
3. A vacuum sucks the sheet into / onto
the mould.
4. The newly shaped sheet is taken off
the mould.
3. Typical PLASTICS used in the
vacuum forming process
POLYCARBONATE
(PC)
Acrylonitrile Butadiene Styrene
(ABS)
POLYSTYRENE
(PS)
4. Further PLASTICS used in the
vacuum forming process
POLYPROPYLENE
(PP)
POLYETHYLENE (woven sheet)
PE
POLYVINYL CHLORIDE
(PVC)
ACRYLIC
(PMMA)
5. Advantages of
the Vacuum Forming Process
• Vacuum forming uses low pressures so
only relatively low cost equipment /
components are required.
• Low pressures mean that moulds can be
made of inexpensive materials and in a
short time.
• Prototypes, small and medium quantity
runs can be extremely economical.
.
6. Disadvantages of
the Vacuum Forming Process
• More complicated machines and moulds are
needed for automatic or continuous
production of ‘high volume’ items,
eg. disposable cups and sandwich packs.
• The vacuum forming process starts with a flat
plastic sheet and there may be a need for a
second process to trim the moulded end
product. This means more expense to obtain
additional equipment.
• NB. The trimmed waste, however, can be re-ground and recycled!
7. Summary of the
Vacuum Forming Process
1. The process requires heat, suction, and
(thermo)plastic sheets.
2. Hot air is required to soften the plastic sheet
and allow it to conform easily to the shape of
the mould.
3. Vacuum is then used to suck the
plastic to the mould.
Vacuum Forming is one of the most
Common methods of producing both
low and high volumes of moulded useful
forms that play a major role in our lives.
