Required Clamp Force
Required clamp force affects machine selection (see
Machine Feasibility and Selection). It is calculated with the following formula:
Required Clamp Force =
((Part Projected Area * Number of Cavities) + Runner Area) *
Injection Pressure * Clamp Safety Factor
Required clamp force depends on the following factors:
• Part projected area: this is the projected area of the molded subcomponents. It is the value of the PartingLine property projectedMoldedArea, obtained from GCD extraction.
• Runner area (see
Runner System Model).
• Injection pressure (see Injection Pressure, below)
• Clamp safety factor: specified by the cost model variable clampForceSafetyFacter (1.1 in starting point VPEs).
Injection Pressure
Injection pressure is estimated by applying various adjustments to the material property Injection Pressure Max. The largest of the following is then used in the clamping force calculation:
• Adjusted pressure estimation
• Material property Injection Pressure Min
• Cost model variable minInjectionPressure
The adjustments to the material property Injection Pressure Max include the following:
• Adjustment by a factor that reflects whether the gating system uses hot drops. The adjustment is specified by one of the following cost model variables:
o hotRunnerMultiplier (0.85 in starting point VPEs)
o conventionalRunnerMultiplier (0.7 in starting point VPEs)
• Adjustment by empirically-derived factor reflecting the effect of one of the following (whichever effect dominates):
o Number of mold cavities
o Nominal wall thickness
o Cavity-length-to-nominal-wall-thickness ratio