Blow molding is a manufacturing process that uses compressed air to inflate heated plastic against a mold to form hollow plastic parts. Products made through blow molding include packaging for foods, liquids, and medicines, as well as automotive fuel tanks, toys, and household items. The blow molding process involves extruding a hollow plastic tube called a parison, closing the mold around the parison, and inflating the soft plastic with compressed air to take the shape of the mold cavity before opening the mold. Design considerations for blow molded parts include the material, size, contours, texture, edges and corners of the part.

1. BLOW MOULD
PROCESS
Blow molding is a manufacturing process that is used to produce hallow plastics parts
by inflated a heated plastics until it conforms to the mold shape and form the desired product.
PODUCTS OF BLOW MOLDING

2. Applications of Blow Molded Parts
Packaging for Milik, fluids, medicines, cosmetics, etc.
Automotive fuel tanks, oil bottles, air ducts and seat backs.
Consumer products like toys, house-wares, sports goods etc.
Drums for chemical industries.
Bellow shaped shield and double walled carrying case.

3. 1). The blow moulding cycle starts
with the mould open.
A hollow length of plastic, called a
parison, is extruded down between
the two halves of the mould.
2). The mould closes over
the parison.
3). Compressed air inflates
the soft plastic.
Blow Moulding Process
Fig-1
Fig-2
Fig-3
Fig-4
4). Mould opens and
the moulding removed

10. Design of a blow moulded bottle & other shapes requires consideration
of the following factors :-
1) Material to be blown
2) Size & Weight of the product & mould
3) Contours on the part
4) Surface texture & engraving
5) Sharp corners & straight edges
6) Blow opening available & locations
7) Parting lines
Blow Moulded Part Design Considerations

11. Corner & Edge Rounding

12. Base Design
To avoid the rocking bottom phenomenon, in case of flat bottom parts, the typical solution is
to provide a doomed recess in the base, called push-up.
On stretch blown PET bottles/containers, the base must be spherical due to internal
pressure. Petaloid type base provides a self-standing container with several egg-shaped feet
on which it balances.

13. Materials for Blow Mould Construction
1). Aluminum alloy : Aircraft grade aluminum
2). Beryllium-Copper (Be-Cu) alloy
excellent thermal conductivity, corrosion-resistance
& mechanical toughness.
3). Steel : for blow moulds for PVC or engineering resins,
AISI-P20 pre-hardened steel is widely used.
For corrosive resins, AISI-420 stainless steel.
4). Miscellaneous Materials : Zinc alloy (Kirksite)

14. Parison Dies

19. PINCH OFF DESIGN