2. Injection Mold
A tool is comprised of a series of parts that allows molten
plastic to be formed and cooled in such a way as to create a
discrete part shape.
3. Core (B) side
Parts sticks on here (hopefully)
On moving side of press/platen
Has ejector system
Cavity (A) side
On stationary (barrel) side of press/platen
Has gate/sprue/runner
MATERIAL INJECTION
TOP LEVEL
5. Clamp Plates
Mold halves are attached to the molding platens by the clamp plates.
Mold Clamps use large bolts to hold them in place; other machines hold the mold
onto the platen with magnets
PLATEN
CLAMP PLATE
Mold clamps
6. Nozzle / Sprue Bushing
Liquified plastic is pushed through the nozzle of the barrel of the molding machine.
The nozzle seats against a surface on the mold called the sprue bushing and locating ring,
which help center the nozzle to the mold.
SPRUE
BUSHING
(in mold)
NOZZLE
(on machine)
7. Feed System
Plastic flows through the sprue bushing in a sprue, then to individual runners which
take the material the gates – the entry point of the material to the individual cavities.
The sprue and runners can be reground (chopped up) and reused again. They can be
eliminated by using a hot runner system.
HOT RUNNER SYSTEM
8. Cavity
Cavities are areas of the mold where the part is formed into the desired shape.
Molds must be balanced, so there are typically only a certain number of
cavitations allowed (1, 2, 4, 8, etc.)
9. Cooling System
Plastic in injected hot, and is cooled by cooling
channels that allow conduction to cool the part.
Working fluid is typically water, although oil can be
used in high-temp applications.
10. Guide Pillars / Bushings
Cavity and Core mold halves are insured to be in proper alignment during mold close
by the use of Guide Pins (or Pillars) and Guide Bushings (or Sleeves).
11. Ejector System
Parts are pushed off of the core using a series of pins or bars; these series
of pins or bars is called the Ejector System.
12. Ejector Plate System
The Ejector Pins are mounted in an Ejector Plate – the motion of the Ejector Plate
forward allows the pins to move forward, pushing the part off the core. The Ejector
Retaining Plate holds the pins onto the Ejector Plate.
