When you're specifying a mold base, the structure you pick dictates everything downstream—parting line layout, ejection, cooling, and guiding. The 24 typical configurations covered in standard mold base design references break down into a few families: two-plate (A-type) for simple single-face parts, three-plate for multi-cavity pin-point gating, and variants with stripper plates, hot runners, or sliding cores. In practice, an A-type base with a 250×250 mm plate and standard 20 mm thick cavity insert handles most small-to-medium jobs. Once you add a stripper plate for cup-shaped parts or a slide for undercuts, you're looking at a B-type or a custom base with additional guide pillars and bushings. The parting surface must be chosen before anything else—it determines whether you need side cores, angled lifters, or a split cavity.

Ejection and cooling are where most mold base designs fail in the field. For a typical 100-ton press running a 2-cavity ABS part with a 30 mm shot, you want ejector pins on a 50–80 mm grid, with a return pin spring rated for at least 1.5 times the ejector plate weight. Cooling lines should sit 12–15 mm from the cavity surface, with a diameter of 8–10 mm and a flow rate around 4–6 L/min per circuit. Guide pillars need a clearance of 0.02–0.03 mm on the bushings; any tighter and you'll gall the steel after 50,000 cycles. Don't overlook the support pillars under the core plate—on a 400×400 mm base, four 40 mm diameter pillars prevent deflection that would flash the part.

These 24 structures aren't just textbook diagrams—they're a checklist. Before you cut steel, verify that your selected base can accommodate the ejector stroke, that the cooling circuit doesn't intersect an ejector hole, and that the guide system handles the projected area. If you're sourcing a mold base or need a second opinion on a tricky layout, visit MoldWorld (www.moldw.com) for supplier listings and technical resources. A few minutes of review can save you a week of rework.