How to calculate required clamping force from projected area and cavity pressure for an injection molding machine?
• Clamping force = projected area of parts and runner (cm²) × average cavity pressure (kg/cm²) ÷ 1000 in tonnes.
• Cavity pressure by material: 300-400 for PP/PE, 400-500 for ABS, 500-700 kg/cm² for PC.
• For multi-cavity molds, sum projected area of all cavities plus runner, not a single cavity.
• Select a machine with 20%-30% clamping force margin to prevent mold opening and flash.
• Check toggle stroke and minimum mold height so the mold fits and ejection stroke suffices.
• Cavity pressure by material: 300-400 for PP/PE, 400-500 for ABS, 500-700 kg/cm² for PC.
• For multi-cavity molds, sum projected area of all cavities plus runner, not a single cavity.
• Select a machine with 20%-30% clamping force margin to prevent mold opening and flash.
• Check toggle stroke and minimum mold height so the mold fits and ejection stroke suffices.