Calculation Formula for Total Area of Ejector Pins

Conversion Between Different Units of Yield Strength
kgf/cm² MPa MPa kgf/cm²
61.78 632.214
Calculation Formula 1
Ejection Force (kgf) Ejection Force, Ft (N) Mold Core Area Enveloped by Side Walls and Ribs, A (mm²) Coefficient of Holding Force per Unit Area on the Core
P (2.4–3.9) / (0.8–1.2) (10^7 Pa)
Coefficient of Friction between Plastic Part and Steel
µ (0.1–0.3)
Minimum Draft Angle (°)
4772 46801
Calculation Formula 2
Ejection Force (kgf) Ejection Force, Ft (N) Mold Core Area Enveloped by Side Walls and Ribs, A (mm²) Adhesion Force between Plastic Part and Mold
(0.5–1.5) (MPa)
2753 27000
Ejection Stress per Unit Area, A (MPa) Ejection Force, FtC (N) Total Contact Area of Ejector Pins / Blocks / Lifters
(mm²)
Tensile Yield Strength of Plastic, B (MPa)
There is a risk of ejector pin marks or ejection cracks on the part. Consider increasing the ejection contact area by adding ejector pins, ejector blocks, or lifters.
78.00
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Note