Punching
aPriori uses the formulas below to determine costs associated with punching processes (used for hole making).
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) / Process Yield
Labor cost is a function of the following:
• Labor time (see formula above)
• Machine labor rate (specified by a machine property)
• Process yield (see formula below)
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)
Process Yield = 1 / (Machine Process Yield/100)
Process yield depend on the machine property Process Yield.
Cycle Time Calculation
Cycle Time = (Total Punching Time / Number Punching Heads) + Load and Unload Time
Cycle time depends on the following:
• Total punching time (see formula below)
• Number of punching heads (specified as the machine property Number of Heads)
• Load and unload time (obtained from a lookup table—see below; increases with part mass, which increases with material density)
Total Punching Time = Punch Time + Traverse Time
Total punching time is the sum of the following:
• Punch time, which depends on whether holes are coaxial, as well as the following machine properties:
o Mandrel Punch Time, or Non Mandrel Punch Time
o Axial Feed Rate
• Traverse time, which depends on the following:
o Distance between holes
o Machine property Axial Feed Rate
Load and unload times by part mass are contained in the lookup table punchHandling.
See
User Inputs for information on mandrel bending.