Times

Times such as labor time and cycle time are calculated as described below.

Labor Time = Cycle Time x Number of Operators

Labor time is the product of the following:

  • Cycle time (see formula below)

  • Number of operators (specified by machine property, typically 0.5)

Cycle Time = (Injection Time +
Cool Time + Ejection Time ) / Number of Cavities

Cycle time is computed by default, but can be specified by the user; see Additional User Inputs. If calculated, it is a function of the following:

  • Injection time (see formula below)

  • Cool time (see formula below)

  • Ejection time (see formula below)

  • Number of cavities (see Number of Mold Cavities)

This value is adjusted by multiplying by the cost model variable cycleTimeAdjustmentFactor  (which defaults to 1; see Process Defaults and Thresholds).

Injection Time = ((Number of Cavities x Part Volume) +
Runner Volume) / Adjusted Injection Rate

Injection time is function of the following:

Adjusted Injection Rate = Injection Rate x 0.25

Adjusted injection rate is one quarter of the injection rate of the machine.

Cool Time = 0 – ((Nominal Wall Thickness^2) /
(2 x π x Material Thermal Diffusivity) x ln(π/4) x
(Eject Deflection Temperature – Mold Temperature) /
(Melting Temperature – Mold Temperature)

Cool time is a function of the following:

  • Nominal wall thickness (see Nominal Wall Thickness)

  • Material properties (listed in the  Material Selection dialog):

    • Thermal diffusivity

    • Eject deflection temperature (temperature at which the part can be ejected from the mold without deformation)

    • Melting temperature

    • Mold temperature (required temperature of the mold to support proper molten polymer flow)

      Note: Cool time includes packing time, during which pressure is applied to the injected plastic in order to provide better finish and tolerance for part surfaces.

      Ejection Time = Dry Cycle Time of Machine x 1.5

      Ejection time is 50% greater than the machine dry cycle time.