All credit goes to the creators, my colleagues.

1. Vacuum bag forming
and pressure bag
forming

2. What isVacuum-Bag Forming ?
• also known as vacuum bagging and vacuum bag molding.
• It’s an open moulding techinque.
• It’s a clamping method which is used to hold adhesive and
resin coated components of a lamination.
• (When discussing composites, “resin” generally refers to the
resin system— mixed or cured resin.)
• simplified version of thermoforming

3. What are applications
• can be used in place of complex fabricated sheet
metal, fiberglass, or plastic injection molding.
• In automated teller machines
• for medical imaging and diagnostic equipment such as
magnetic resonance imaging (MRI) machines
• engine covers in a truck cab
• often used by hobbyists, for applications such as RC
cars and masks.

4. Apparatus
• Vacuum pump
• Two way shut-off valve
• Vacuum tubing
• Vacuum gauge
• Vacuum connector
• Vacuum bagging film
• Breather and bleeder
• Release peel ply
• Release film (optional)
• SealantTape
• Mold.
• Part / laminate

6. Process of vacuum forming• First, a mould is made. This is made in the shape to which the plastic will
form around.
• the mould should have angled edges, in order to allow the tooling to
pop out of the plastic when made.
• The mould is then placed into the vacuum former oven. A plastic sheet is
then clamped above, but not on the mould.
• In the oven, the heater is positioned above the plastic.This will heat up,
warming the plastic & allowing it to become flexible & mouldable.
• . After a few minutes, the plastic should be at a temperature to allow
moulding.
• The shelf on which the mould is sat on, is moved upwards & into the
flexible plastic using a handle.
• The vacuum is then switched on, removing all air from the oven.This
allows the plastic to form to the shape of the mould.
• Once cooled, the sheet is then removed from the oven, the mould is
removed & any excess trimmed.

8. Materials Options
• Resins: Primarily epoxy and phenolic. Polyesters and
vinylesters may have problems due to excessive
extraction of styrene from the resin by the vacuum
pump.
• Fibres: The consolidation pressures mean that a
variety of heavy fabrics can be wet-out.

9. Advantages of vacuum bag
forming
• Higher fibre content laminates can usually be achieved than
with standard wet lay-up techniques.
• Lower void contents are achieved than with wet lay-up.
• Better fibre wet-out due to pressure and resin flow
throughout structural fibres, with excess into bagging
materials.
• Health and safety:The vacuum bag reduces the amount of
volatiles emitted during cure.

10. Disadvantages of vacuum bag
forming
• The extra process adds cost both in labour and in
disposable bagging materials
• A higher level of skill is required by the operators
• Mixing and control of resin content still largely
determined by operator skill

11. What is Pressure-Bag Forming ?
• Almost the same process
as vacuum bag molding
except a bag is inflated
forcing the composite
into the mold.

12. Difference between vacuum and
pressure bag forming
• In pressure forming process,Positive
pressure is used in addition to the vacuum
to push the sheet in to the shape
• More complex shapes can be made than
vacuum bagging.
• Surface finishing is good in pressure bag
forming.

14. Applications of pressure bag
forming
• Outdoor plastic housings
• Medical enclosures
• Point of Purchase displays & retail items
• Recreational equipment
• Bezels
• Bases

15. Advantages of Pressure-bag
forming.
• Lower cost tooling than injection molding (less
than 1/3 injection molding cost)
• More cost effective for moderate quantities
(300 – 5,000)
• Able to form very large parts
• Able to form parts with fine cosmetic or
functional details, such as vents or louvers
• Able to confirm to stringent tolerances
• Rapid prototyping and quick time to market

16. Disadvantages of Pressure-
bag forming.
• The extra process adds cost both in labor
and in disposable bagging materials.
• A higher level of skill is required by the
operators.
• Mixing and control of resin content still
largely determined by operator skill.

17. Materials used for this process
• ABS – impact resistant, available in a variety of colors,
textures, flame retardant grades
• PC – impact & high temperature resistant
• HDPE – inexpensive; impact, chemical and cold
temperature resistant
• TPO – good durability, impact resistant
• HIPS – cost effective, available in a variety of colors
• PVC – impact resistant, available in a variety of colors,
textures, flame retardant grades

18. ThankYou
!