Cycle Time for the Stretch Form Process
Cycle Time = Process Time * Cycle Time Adjustment Factor
Cycle time is the product of the following:
• Process time: unadjusted cycle time for the current process. See the formula below.
• Cycle Time Adjustment Factor: value of the cost model variable cycleTimeAdjustmentFactor. This is set to 1 in aPriori starting point VPEs. VPE administrators can change the cost model variable to globally adjust cycle times.
Process Time = Identing Time + Locating Hole Drilling Time +
Child Operation Time
Process time is the sum of the following:
• Identing time: this is the time required to vibro-etch onto the part a unique identifier (to enable traceability of the part). The total identing time is specified by the cost model variable
defaultIdentingTime (45 seconds in starting point VPEs). If the current routing includes multiple stretches (see
Number of Stretch Form Cycles), this time is amortized over the stretches (that is, the identing time attributed to one process instance is
defaultIdentingTime divided by the number of stretches).
• Locating-hole drilling time: this is the time required to drill the locating hole. The total locating-hole drilling time is specified by the cost model variable
defaultLocatingHoleDrillingTime (4 minutes in starting point VPEs). If the current routing includes multiple stretches (see
Number of Stretch Form Cycles), this time is amortized over the stretches (that is, the locating-hole drilling time attributed to one process instance is
defaultLocatingHoleDrillingTime divided by the number of stretches).
• Child operation time is the sum of the following:
o Inspecting: inspection time required between stretches. By default this is specified by the cost model variable
defaultInterStretchInspectionTime (30 seconds in starting point VPEs). Users can override the default on a part-by-part basis with the setup option
Inter Stretch Inspection Time.
o Loading: time required to load the part onto the machine. This is looked up by stock mass in the lookup table tblMaterialHandling.
o Pre-Stretching: time required for pre-stretching on tangential machines is specified by the machine property Pre Stretch Cycle Time. Pre-stretching time is 0 for simple (non-tangential) machines.
o Stretch Forming: this is the time required for the stretching operation. The total stretching time is the ram stroke distance (the part height) divided by the machine’s ram stroke speed (specified by the machine property
Ram Stroke Speed). If the current routing includes multiple stretches (see
Number of Stretch Form Cycles), the stroke distance is amortized over the stretches (that is, the stroke distance attributed to one operation instance is the part height
divided by the number of stretches).
o Tool cleaning: this is the time required to clean the tool between stretches. It is looked up by form area in the lookup table tblStretchForm, and bounded below by the cost model variable minimmToolCleanTime (5 seconds in starting point VPEs). The form area is the sum of the areas of all forms of type EMBOSS.
o Tool Lubricating: this is the time required to lubricate the tool between stretches. It includes time to apply the lubricant as well as time to wipe away the excess. The default time to apply the lubricant is specified by the cost model variable
defaultApplyLubricantTime (30 seconds in starting point VPEs). Users can override the default with the setup option
Lubricant Application Time. Time to wipe away the excess is looked up by form area in the lookup table
tblStretchForm. The form area is the sum of the areas of all forms of type EMBOSS.
o Unloading: time required to unload the part from the machine. This is looked up by stock mass in the lookup table tblMaterialHandling.