When you're quoting a new injection mold, the first decision that drives cost and lead time is the mold base structure. The two-plate (A/B plate) base remains the workhorse for single-face parts, typically running in standard 2-plate configurations from 150×150 mm up to 600×600 mm. For parts requiring runner separation or multi-cavity balance, the three-plate base adds a stripper plate to drop the runner automatically — common in 8, 16, or 32-cavity tools for small connectors and caps. In our shop, a 16-cavity three-plate base for a 30 mm cap usually lands around 350×400 mm with a 250 mm shut height, and cycle times stay within 15–20 seconds depending on wall thickness.

Hot runner systems change the game when you're dealing with engineering resins like PC/ABS or glass-filled nylon. A hot half with a manifold and valve gates eliminates runner waste and shortens cycles by 10–30% compared to a cold runner, but you need to account for thermal expansion — typically 0.02–0.04 mm per 100 mm of manifold length. Stack molds double output without increasing tonnage, but they demand precise alignment and a robust ejection system; we usually spec hardened leader pins and a central ejector plate to keep both faces in sync. For deep-draw parts, a standard base with a moving stripper plate or a cam-actuated side core is often more cost-effective than a complex hot runner setup.

Don't overlook plate thickness and material. A 250-ton press running a 400×400 mm base needs at least 35–45 mm A/B plates in P20 or 1.2311 to resist deflection under 800–1000 bar cavity pressure. Insufficient thickness shows up as flash and uneven wall sections. Always cross-check your selected base against the press platen size, tie-bar spacing, and ejector pattern before finalizing the design. For a full library of standard mold base dimensions and supplier comparisons, visit MoldWorld at www.moldw.com — it's a solid starting point for sourcing and reference data.