How to Select Mold Base Structure Based on Mold Type (e.g., Two-Plate Mold, Three-Plate Mold)
Selecting a mold base structure according to the mold type primarily depends on matching its mold opening method and the requirements of the runner (gate) system. The core correspondence is: a two-plate mold pairs with a large gate mold base, while a three-plate mold requires a pinpoint gate or simplified pinpoint gate mold base.
Below is a detailed guide for selection based on mold type:
1. Two-Plate Mold and Large Gate Mold Base
- Recommended Structure: Large Gate Mold Base (Two-Plate Mold Base).
- Characteristics and Reasons for Selection: This is the simplest and most common structure, consisting only of a moving half and a fixed half. The runner and the part are separated and ejected on the same parting surface. Its advantages lie in its simple structure, lowest cost, robustness, and ease of maintenance.
- Application Scenarios: Suitable for parts using large gate feeding methods like edge gates or direct sprue gates. Commonly used for parts with relatively simple structures where gate vestige is not a critical concern.
2. Three-Plate Mold and Pinpoint Gate Mold Base
- Recommended Structure: Pinpoint Gate Mold Base (Three-Plate Mold Base) or its variant—the Simplified Pinpoint Gate Mold Base.
- Characteristics and Reasons for Selection: A three-plate mold adds a movable runner stripper plate between the moving and fixed halves, enabling a three-stage opening sequence: first, separating the runner from the part; then, dropping the runner; and finally, ejecting the part. This makes pinpoint gate feeding possible, allowing the gate to be automatically severed and providing better part surface quality.
- Subtypes:
- Standard Pinpoint Gate Mold Base: Offers full functionality, ensuring reliable runner stripping via the runner stripper plate. Used for molds with high aesthetic requirements, needing multi-point feeding, or with complex cavity layouts.
- Simplified Pinpoint Gate Mold Base: Omits the runner stripper plate, controlling the opening sequence with pull rods and limit pins. The structure is more compact than the standard version, with slightly lower cost, making it a common alternative when space or budget is limited.
Key Selection Points Summary:
- The primary deciding factor is the gate type: If planning to use a large gate like an edge gate, choose a Two-Plate Mold structure. If a pinpoint gate is required, a Three-Plate Mold structure is necessary.
- Balance part requirements and cost: Two-plate molds offer lower cost and higher reliability; three-plate molds enable better gate location and aesthetic quality but are more complex, costly, and result in a thicker mold.
- The final selection should also comprehensively consider practical factors such as part design, production volume, and injection molding machine specifications.
