Plastic Mold Design Formula Calculator

Mold Cavity/Core Dimension Calculation

Part Nominal Dimension (Lp):
Plastic Shrinkage Rate (k, e.g., 0.005 for 0.5%):
Part Dimension Tolerance (Δ):
Mold Manufacturing Tolerance (δ, e.g., Part Tolerance / 3 to / 6):
Calculate Dimensions

Cavity Radial Dimension (Lm):

Cavity Depth Dimension (Hm):

Core Radial Dimension (Lc):

Clamping Force Calculation

Mold Cavity Projected Area (Am in cm²):
Filling Pressure (Pv in kg/cm², typically 150-350):
Calculate Clamping Force

Clamping Force (F in TON):

Injection Pressure Calculation

Pump Pressure (P in kg/cm²):
Injection Oil Cylinder Effective Area (A in cm²):
Screw Diameter (D in cm):
Calculate Injection Pressure

Injection Pressure (Pi in kg/cm²):

Injection Volume/Weight Calculation

Screw Diameter (D in cm):
Injection Stroke (ST in cm):
Material Specific Gravity (η):
Mechanical Efficiency (δ, typically 0.95):
Calculate Injection Volume/Weight

Theoretical Injection Volume (V in cm³):

Injection Weight (Vw in g):

Cooling Time Calculation (Simplified)

This is a simplified estimation. Precise calculation involves complex thermal properties.

Part Wall Thickness (s):
Melt Temperature (Tm):
Mold Wall Temperature (Tw):
Ejection Temperature (Te):
Plastic Thermal Diffusivity (α, approx. 1.0E-7 m²/s = 1.0E-3 cm²/s):
Calculate Cooling Time

Cooling Time (tc in seconds):

Runner Diameter Calculation (Empirical)

Part Weight (W in g):
Runner Length (L in mm):
Empirical Constant (C, varies by material/experience):
Calculate Runner Diameter

Runner Diameter (D in mm):

Mold Plate Thickness Calculation

This calculation is based on a simplified model for deflection of a uniformly loaded plate.

Filling Pressure (Pv in MPa or N/mm²):
Shortest Span (a in mm, distance between supports/bolts):
Elastic Modulus of Plate Material (E in MPa or N/mm², e.g., Steel ~200000):
Allowed Max Deflection (δmax in mm, e.g., 0.05-0.1 mm):
Deflection Factor (k, depends on plate aspect ratio and support):
Calculate Plate Thickness

Required Plate Thickness (h in mm):

Note: Typical ‘k’ values for a square plate (aspect ratio 1.0) with four simply supported edges are around 0.0443.