Passivation formulas
Below is the cycle time formula for Passivation.
Note that starting point VPEs provide machines with Setup Time set to 0. Tank setup for parts with a given material is typically good for all parts with that material, so setup is usually not required for each production batch.
Cycle Time = Process Time * Adjustment Factor
Cycle time includes setup time per part. It is the product of the following:
• Process time (see formula below)
• Adjustment factor (specified by the cost model variable cycleTimeAdjustmentFactor). This factor is 1 in aPriori starting point VPEs. VPE administrators can modify cycleTimeAdjustmentFactor in order to adjust cycle times across processes within the current VPE.
Process Time = Passivation Time / Number of Parts per Load
Process time depends on the following:
• Passivation time: time for one load, looked up in the global lookup table
passivationTreatments. Each row of the lookup table represents a passivation treatment that uses specific solutions and temperatures. By default, aPriori finds the treatment with the shortest time that is appropriate for the part (based on the material’s cut code and whether the part has been machined). If no appropriate treatment is found, the longest treatment time in the table is used. Users can override the default and specify a treatment explicitly with the PSO
Passivation Treatment.
• Number of parts per load: number of appropriately spaced parts that fit in the tank working zone. By default this is specified by the formula below. Users can specify this value explicitly with the PSO
Number of Components Per Passivation Tank.
Number of Parts per Load = Number of Parts Lengthwise * Number of Parts Widthwise
Number of appropriately spaced parts that fit in the machine working zone. If not specified explicitly with the PSO
Number of Components Per Passivation Tank, this depends on the following:
• Number of parts lengthwise (machine property Machine Window Length divided by the part’s longest dimension)
• Number of parts widthwise: the number of parts at a time that are assumed to fit widthwise is the maximum number that satisfies both size and weight constraints. The size constraints are determined by the following factors:
o Smaller two of the three part dimensions (the longest dimension is assumed to be aligned with the length of the tank)
o Machine property Machine Window Height
o Machine property Machine Window Width
o Machine property Part Spacing Factor: this is the fraction of tightly spaced parts that can fit when the parts are spaced appropriately. Consider, in other words, the number of parts that can fit when the parts are tightly packed, with no space between them; this factor times that number of parts is the number of parts that can fit when the parts are spaced appropriately.
The weight constraints are determined by the following factors:
o Number of parts per tank (product of the number of parts per row—part length divided by Machine Window Length—and the number of parts widthwise)
o Part mass (part volume times material density)
o Machine property Machine Weight Limit