Key Terms in Injection Molding Industry: A Must-Know Guide

1. Mold Structure Terms

• Mold Base: The framework of the mold, including plates, guide pins, and ejector systems.

• Cavity: The concave part of the mold that shapes the exterior of the product.

• Core: The convex part forming the interior features of the product.

• Parting Line (PL): The interface where the two mold halves meet.

• Slider: A side-action mechanism for forming undercuts or side holes.

• Lifter: An angled ejector pin used to release internal undercuts.

• Gate: The entry point where molten plastic flows into the cavity (e.g., pin gate, edge gate).

• Runner: The channel directing plastic from the nozzle to the gate (Hot Runner vs. Cold Runner).

  
  

2. Injection Molding Process Terms

• Injection: The process of forcing molten plastic into the mold.

• Holding Pressure: Additional pressure applied to compensate for material shrinkage.

• Cooling Time: The duration required for the plastic to solidify.

• Sink Mark: A surface depression caused by uneven cooling.

• Flash: Excess plastic leaking from the parting line.

• Weld Line: A visible seam where molten plastics meet.

3. Common Defects

• Short Shot: Incomplete filling of the mold cavity.

• Flow Mark: Wavy patterns due to inconsistent flow.

• Ejector Mark: White marks left by ejector pins.

• Scratch: Surface damage during demolding.

• Air Trap: Trapped gas causing burns or voids.

4. Mold Actions

• Mold Opening: Separation of the two mold halves.

• Ejection: Pushing the finished part out of the mold.

• Core Pulling: Retracting side cores to release undercuts.

• Mold Closing: Rejoining the mold halves for the next cycle.

5. Types of Molds

• Two-Plate Mold: Simplest design with one parting line.

• Three-Plate Mold: Features an additional plate for gate separation.

• Stack Mold: Multi-layer mold for higher productivity.

• Two-Shot Mold: For molding two different materials in one cycle.

6. Materials & Manufacturing

• P20, 718H, NAK80: Common mold steel grades.

• EDM (Electrical Discharge Machining): Using sparks to shape metal.

• CNC Milling: Precision machining of mold components.

• Polishing: Achieving a mirror-like surface finish.

7. Additional Key Terms

• Mold Layout: Arrangement of cavities in multi-cavity molds.

• Undercut: A feature preventing straightforward ejection.

• Mold Temperature Controller: Device regulating mold temperature.

• Trial Run: Initial test production to validate mold performance.

Conclusion
Mastering these terms will enhance your efficiency in the injection molding industry, whether you're designing molds, troubleshooting defects, or optimizing production.