Components of an Injection Mold

Learn the basics about the components that make up an injection mold.

1. COMPONENTS OF AN INJECTION MOLD

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

4. DETAILED COMPONENTS Cavity (A) side (stationary side) Locating Ring Sprue (Bushing) Clamp Plate Clamp Slot Guide Pin Cooling Channel (Water Lines) Cavity Core (B) side (moving side) Core Ejector Pin Guide Pin Ejector Plate Ejector Retaining Plate Support Pillar Clamp Slot

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.

13. Questions? Contact your custom molder for answers to specific questions about your design.