Part Curing Formulas
Part Curing formulas and calculations are covered in the following sections:
Cycle Time Formula
Cycle Time = Process Time * Adjustment Factor
Cycle time is the product of the following:
• Process time (see formula)
• 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 = Elapsed Cure Time / Number of Parts
Process time depends on the following:
• Elapsed cure time (see Elapsed Cure Time)
• Number of parts (see Number of Parts for Part Curing)
Elapsed Cure Time
The cost model uses the steps below to determine elapsed cure time:
1 Estimate the elapsed cure time based on part surface area. The cost model uses an empirically derived linear function of surface area.
2 Estimate the elapsed cure time based on part volume. The cost model uses an empirically derived linear function of volume.
3 Elapsed Cure Time is the larger of the following:
• Result of step 1 (area-based estimate)
• Result of step 2 (volume-based estimate)
unless this is greater than the maximum cure time as specified by the cost model variable curingMaxCureTime (1800 seconds in starting point VPEs), in which case Elapsed Cure Time is curingMaxCureTime.
Number of Parts for Part Curing
This is the number of parts that can be cured at one time, that is, the maximum number of parts that satisfy both the following:
• Space constraint: they can all fit in the curing oven. The cost model assumes rectangular nesting, with a border around each part specified by the cost model variable nestingAllowance (5mm in starting point VPEs).
• Mass constraint: their total mass is no greater than the machine property Maximum Mass.
By default, the cost model uses the steps below in order to determine this number. Users can override the default value with the setup option Number of Parts.
1 Find the maximum number of lengthwise-oriented parts that fit in the oven.
 
rounddown (Machine Bed Length / (Part Length + (2 * Nesting Allowance))) *
rounddown (Machine Bed Width / (Part Width + (2 * Nesting Allowance)))
(Lengthwise orientation means that the part’s length is aligned with the platform’s length and the part’s width is aligned with the platform’s width.)
2 Find the maximum number of widthwise-oriented parts that fit.
 
rounddown (Machine Bed Length / (Part Width + (2 * Nesting Allowance))) *
rounddown (Machine Bed Width / (Part Length + (2 * Nesting Allowance)))
(Widthwise orientation means that the part’s width dimension is aligned with the platform’s length and the part’s length is aligned with the platform’s width.)
3 Pick the larger of the values found in 1 and 2, above. This is the maximum number of parts that satisfy the space constraint (unless it is 0, in which case the maximum number of parts that satisfy the space constraint is 1).
4 Find the maximum number of parts that satisfy the mass constraint:
rounddown (Machine Maximum Mass / Part Mass)
5 The Number of Parts is the smaller of the following two values:
• Result of step 3 (maximum number of parts that satisfy the space constraint)
• Result of step 4 (maximum number of parts that satisfy the mass constraint)
Additional Direct Costs for Part Curing
Additional Direct Costs = Nitrogen Cost / Final Yield
Additional direct costs depend on the following:
• Nitrogen cost (see formula)
Nitrogen Cost = Nitrogen Used * Nitrogen Cost Per Volume
Nitrogen cost is the product of the following:
• Nitrogen used: if the current machine requires nitrogen, this is the product the elapsed cure time (see Elapsed Cure Time) and the nitrogen consumption rate as specified by the machine property Nitrogen Cost. The machine property Requires Nitrogen indicates whether the machine requires nitrogen.
• Nitrogen cost per volume (specified by the machine property Nitrogen Cost)