When you're staring down a mold design review, the base structure is usually where the real arguments start. The classic two-plate mold remains the workhorse for simple, single-face parts—straightforward parting, direct sprue gating, and a standard ejector pin setup that any mold shop can machine without drama. Step up to a three-plate design and you gain the ability to gate away from the parting line, which matters when you're running multi-cavity tools or need a pin-point gate for cosmetic parts. The trade-off is a more complex runner system and a taller stack height, so you'd better check your press daylight before committing.

Hot runner systems change the game entirely. By keeping the melt at temperature right up to the gate, you eliminate runner scrap and cut cycle time—often by 15–30% depending on wall thickness and material. But you're now dealing with manifold thermal expansion, gate seal-off, and wiring that has to survive millions of cycles. For engineering resins like PC or PA with glass fill, a hot runner with a valve gate gives you the surface finish and dimensional control that a cold runner simply can't match. The 24 structures in this reference cover everything from standard A/B plates to complex stack molds and unscrewing cores for threaded parts.

What ties all these designs together is the ejection strategy. Whether you're running a stripper plate, a sleeve ejector, or a pneumatic valve, the mold base has to support it without flexing under injection pressure. Support pillars, guided ejection, and proper venting aren't optional—they're what separate a tool that runs for a million shots from one that flashes and shorts out after 50,000. If you're sourcing mold bases or need to compare standard vs. custom structures, visiting MoldWorld (www.moldw.com) is a solid starting point for supplier and design references.