Fiber Laser Cut
Accounting Calculations
Labor Time = Cycle Time * Number of Operators * Machine Labor Time Standard
Labor time is the product of the following
• Cycle time (see
Cycle Time Calculation below)
• Number of Operators: by default, this is specified by the machine property
Number of Operators. Users can override the default on a per-part basis with the setup option
Number of Operators.
• Machine labor time standard (specified as a machine property). This value reflects the amount of time spent by machine operators in between machine cycles, including time performing maintenance and cleaning tasks as well as time pausing between tasks. The amount is expressed as a cycle time multiplier.
Labor Cost = Labor Time * Machine Labor Rate
Labor cost is a function of the following:
• Labor time (see formula above). aPriori converts labor time from seconds to hours for use in this formula, since machine labor rate is
• Machine labor rate (specified as a machine property)
Amortized Batch Setup =
(Machine Setup Time * (Machine Labor Rate + Direct Overhead Rate)) /
Batch Size
Amortized batch setup cost depends on the following:
• Machine setup time (specified as a machine property)
• Machine labor rate (specified as a machine property)
• Direct overhead rate (see
Direct and Indirect Overhead)
Cycle Time Calculation
Cycle Time = Process Time * Cycle Time Adjustment Factor
Cycle time is the product of the following:
• Process time: see
Process Time.
• Cycle time adjustment factor: value of the cost model variable cycleTimeAdjustmentFactor. This is set to 1 in aPriori starting point Digital Factories. Digital Factory Administrators can change the cost model variable to globally adjust cycle times.
Process Time
The way that process time is calculated depends on the value of the machine property De-Nesting Method for the current machine.
• Shuttle table: process time is the
larger of
Sheet Cutting Time and
De-nesting Time. (The cost model assumes that de-nesting is performed by operators concurrently with cutting, and calculates the times for both de-nesting and cutting.)
• No shuttle table: process time is the
sum of
Sheet Cutting Time and
De-nesting Time. (The cost model assumes that de-nesting is performed by operators after cutting is complete, and calculates the times for both de-nesting and cutting.)
• Automated: process time is
Sheet Cutting Time. (The cost model assumes that de-nesting is performed by operators concurrently with cutting and that it takes less time than cutting. So the cost model only needs to calculate cutting time.)
• Any other value: process time is the
larger of
Sheet Cutting Time and
De-nesting Time. (The cost model assumes that de-nesting is performed by operators concurrently with cutting, and calculates the times for both de-nesting and cutting.)
Sheet Cutting Time
Sheet Cutting Time =
(Cut Time + Pierce Time +
Rapid Traverse Time + Scrap Cutting Time + Shuttle Time) /
Machine Number of Heads
Sheet cutting time depends on the following:
• Cut time, which depends on the following:
o Feed rates (see below)
o Feature perimeters—cut time increases with hole size.
o Feature radii of curvature—tighter cuts are slower.
• Pierce time, which depends on the following:
o Number of holes
o Number of tabs per part
o Per-GCD pierce time (see below)
• Rapid traverse time, which depends on the following:
o Part bounding box dimensions
o Number of holes
o Machine property Rapid Traverse Rate
• Scrap cutting time
• Shuttle time, which depends on
o Machine property Shuttle Time
o Number of parts per stock sheet
• Machine property Number of Heads
Feed rates and per-GCD pierce times are looked up in the lookup table sheetMetalNestingCutRate by all the following values:
• Material family
• Machine power
• Blank thickness
In the table, values in the column Feed Rate Small Features are used for features whose radius of curvature is no greater than the product of the part thickness and the machine property Small Feature Thickness Ratio, bounded below by the machine property Small Feature Feed Radius. Values in the column Feed Rate Large Features are used for all other features.
De-nesting Time
De-Nesting Process Time =
Labor Independent De-Nesting Process Time +
Labor Dependent De-Nesting Process Time
De-nesting time is the sum of the following:
• Labor independent de-nesting process time: the time for de-nesting tasks whose eleapsed time is independent of the number of operators.
• Labor dependent de-nesting process time: the time for de-nesting tasks whose eleapsed time is inversely proportional to the number of operators.
Labor Independent De-Nesting Process Time =
Shuttle Time per Part + Sheet Removal Time per Part
De-nesting time is the sum of the following:
• Shuttle time per part: this is the value of the machine property Shuttle Time divided by the number of parts that can fit on the selected stock sheet as determined by the true-part nesting algorithm or the rectangular nesting algorithm.
• Sheet removal time per part: see formula.
Labor Dependent De-Nesting Process Time =
(Removal Time per Part + Tab Grind Time per Part) / Number of Operators
De-nesting time is the sum of the following:
• Removal time per part: by default, this is looked up by size (blank length, width, and thickness) in the lookup table
tblMaterialHandlingBySize. If no appropriate entry is found in
tblMaterialHandlingBySize, removal time is looked up by part weight in
tblMaterialHandling. Users can override the default on a per-part basis with the setup option
Part Removal Time..
• Tab grind time per part: this is 0 if either of the following hold:
o Setup option
Tab Grinding is set to
false. (It is set to
true in starting point Digital Factories. Administrators can customize the default with the cost model variable
defaultIncludeTabGrindTime.)
o Blank’s length and width are both greater than or equal to the cost model variable tabSizeThreshold (254mm in starting point Digital Factories).
If
Tab Grinding is
true and blank length or width is less than
tabSizeThreshold, tab grind time is given by the formula below.
• Number of operators: by default, this is specified by the machine property
Number of Operators. Users can override the default on a per-part basis with the setup option
Number of Operators.
Tab Grind Time per Part =
(Tab Grind Time per Stack * Tabs per Part * Number of Grind Stacks) /
Total Number of Parts per Sheet
Tab grind time per part depends on the following:
• Tab grind time per stack: by default, this is specified by the cost model variable
defaultGrindTimePerStack (10 seconds in starting point Digital Factories). Users can override the default on a per-part basis with the setup option
Tab Grind Time per Stack.
• Tabs per part: by default, this is specified by the cost model variable
defaultNumTabs (2 in starting point Digital Factories). Users can override the default on a per-part basis with the setup option
Number of Tabs per Part.
• Number of grind stacks: see formula.
• Total number of parts per sheet: this is the number of parts that fit on the selected stock sheet, as determined by the true-part nesting algorithm or the rectangular nesting algorithm.
Number of Grind Stacks =
roundup(Total Number of Parts per Sheet / Number of Parts per Stack)
The number of grind stacks depends on the following:
• Total number of parts per sheet: this is the number of parts that fit on the selected stock sheet, as determined by the true-part nesting algorithm or the rectangular nesting algorithm.
• Number of parts per stack: this is 1 if the blank thickness exceeds the value of the cost model variable maxPartStackThickness (40mm in starting point Digital Factories). Otherwise, this is the maximum number of parts that form a stack whose total thickness does not exceed maxPartStackThickness.
Sheet Removal Time per Part =
(Shuttle Time / Total Number of Parts per Sheet) *
Shuttle Time to Sheet Removal Time Multiplier
Removal time per part depends on the following:
• Shuttle time: specified by the machine property Shuttle Time.
• Total number of parts per sheet: this is the number of parts that fit on the selected stock sheet, as determined by the true-part nesting algorithm or the rectangular nesting algorithm.
• Shuttle time to sheet removal time multiplier: specified by the cost model variable shuttleTimeToSheetRemovalTimeMultiplier (0.5 in starting point Digital Factories).