Band Saw, Circular Saw, Reciprocating Saw
aPriori uses the formulas below to determine costs associated with sawing processes (used for cutting and trimming).
Accounting Calculations
Labor Time = Cycle Time * Machine Labor Time Standard * Machine Labor Ratio
Labor time is the product of the following
• 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.
• Machine labor ratio (specified as a machine property)
Labor Cost = ((Labor Time / 3600) * Machine Labor Rate) / Final Yield
Labor cost is a function of the following:
• Labor time (see formula above)
• Machine labor rate (specified by a machine property)
• Final yield
Amortized Batch Setup =
(Machine Setup Time * (Machine Labor Rate + Direct Overhead Rate)) / Batch Size
Amortized batch setup is a function of 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 = Sawing Time + Handling Time
Cycle time is the sum of the following:
• Sawing time (see formula below)
• Handling time (see formula below)
Sawing Time = First End Cut Time + Other End Cut Times + Feed Forward Time
Sawing time is the sum of the following:
• End cut times, which increase as the following quantities increase:
o End surface area
o Number of planes on ends
Cut times also depend on material type (aluminum, for example, cuts faster than steel).
Cut times are obtained from lookup in one of the following lookup tables, where lookups are keyed by material type and stock width:
o bandSawCutting
o circularSawCutting
o resiprocatingSawCutting
• Feed forward time, which increases with the following:
o Part’s min stock length
Feed forward time decreases with the following:
o Machine’s axial feed rate
Handling Time =
(Load Time / Number Parts Per Stock) +
(Unload Time / Bundle Sawing Count) +
Machine Unload Time
Handling time depends on the following:
• Load time, which increases with the following:
o Minimum stock length
o Part mass (which increases with material density)
Load and unload times are obtained from one of the following lookup tables, where lookup is keyed by stock mass (for load time) or bundle mass (for unload time):
o bandSawHandling
o circularSawHandling
o resiprocatingSawHandling
• Number parts per stock
• Unload time, which increases with part mass (and so with material density).
Load and unload times are obtained from one of the following lookup tables, where lookup is keyed by stock mass (for load time) or bundle mass (for unload time):
o bandSawHandling
o circularSawHandling
o resiprocatingSawHandling
• Bundle sawing count, which
o Is 1 if angled cuts are present on ends
o Decreases with stock width and height
o Increases with machine’s max stock width and height
Bundle sawing refers to the process of loading multiple bars or tubes onto the saw machine to cut multiple stock pieces at once, which in turn reduces cycle time. There is currently a bundle limit of 18 that applies to all processes and all machines. Enable this setting through Process Setup Options for Sawing processes.
• Machine unload time: for extrusions, this is 0. Otherwise, it is specified by the machine property Unload Time.