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

• Cycle time (see Cycle Time Calculation)

• 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) *
Labor Rate) / Process Yield

Labor cost is a function of the following:

• Labor time (see formula above)

• Labor rate: this is the product of the following:

  • Machine property Labor Rate
  • Cost model variable laborRateAdjustmentFactor (1 in starting point Digital Factories)
  • Machine property Work Center Labor Rate Factor (1 in starting point Digital Factories)

• Process yield (see formula below)

Amortized Batch Setup = (Machine Setup Time *
(Labor Rate + Direct Overhead Rate)) / Batch Size

Amortized batch setup is a function of the following:

• Machine setup time (specified as a machine property)

• Labor rate: this is the product of the following:

  • Machine property Labor Rate
  • Cost model variable laborRateAdjustmentFactor (1 in starting point Digital Factories)
  • Machine property Work Center Labor Rate Factor (1 in starting point Digital Factories)

• 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:

  • Mandrel Punch Time, or Non Mandrel Punch Time

  • Axial Feed Rate

• Traverse time, which depends on the following:

  • Distance between holes

  • Machine property Axial Feed Rate

Load and unload times by part mass are contained in the lookup table punchHandling.

See User Inputs for Sand Casting for information on mandrel bending.