Mold opening stroke calculation

The mold must open far enough for the part to drop freely out of the mold or for the robot to pick it. This calculator uses a practical rule of thumb to find the minimum opening stroke. Since the stroke depends on the machine’s clamping system (toggle or direct hydraulic/two-platen), you select the machine type; if you enter your own machine’s stroke, it also checks whether it is sufficient.

What is this calculation used for?

Finds how far the mold must open for the part to drop out or be picked by a robot. Used before mounting a mold to check whether the machine’s opening stroke will be sufficient. The machine type is selected because the opening stroke depends on the clamping system (toggle or direct hydraulic/two-platen).

Loading calculator… (JavaScript required)

How is it calculated?

  • Opening ≥ 2 × part height + runner + robot clearance + safety margin

Results are general engineering estimates; the machine catalog, material data sheet and trial run take precedence.

Other calculators

Clamping force calculation

Required clamping force and machine size from projected area and cavity pressure.

Shot weight calculation

Part and shot weight from raw material density, and machine capacity utilization.

Raw material residence time in the barrel

Melt residence time in the barrel, from barrel capacity, shot weight and cycle time.

Hourly masterbatch consumption for injection molding

Hourly, shift and monthly masterbatch requirement from shot weight, cycle time and dosing ratio.