Pick and Place Formulas

Assembly Weight

Assembly Weight = Component Weight + Weld Weight

Assembly weight affects process and operation cycle times. It is the sum of the following:

• Component weight: sum of the weights of the assembly’s components

• Weld weight: sum of the weights of the assembly’s welds (see MIG Welding Weld Weight, TIG Welding Weld Weight, and Spot Welding Weld Weight)

Clamp Operation Cycle Time Calculation

Cycle time for this operation is the time to clamp the part in the fixture for subsequent operations. It is determined in one of the following ways:

• Specified by the PSO Clamping Time.

• Looked up by assembly weight (see Assembly Weight) in the lookup table xtraLoadTime.

Load Operation Cycle Time Calculation

Cycle Time = Base Load Time * Additional Handling Factor * Difficult Insertion Factor

Cycle time for the Load operation is the time to load the part into the assembly fixture or to a mating part already assembled, including bin pick and insertion time. It is the product of the following:

• Base load time: specified by the PSO Base Load Time or looked up by assembly weight (see Assembly Weight) in the lookup table componentLoadTime.

• Additional handling factor: accounts for handling difficulties such as nesting, stickiness, fragility, and so forth. The factor is 1 by default, or specified by the PSO Load time multiplier for handling difficulties.

• Difficult Insertion Factor: accounts for difficulties with alignment and positioning due to either obstructed access or vision, or lack of alignment features such as chamfers and lead-ins. The factor is 1 by default, or specified by the PSO Load time multiplier for insertion difficulties.

Reorient Operation Cycle Time Calculation

Cycle time for the Reorient operation is determined in one of the following ways:

• Specified by the cost model variable reorientTime (9 seconds in aPriori starting point VPEs).

• Specified by the PSO ReOrient - Turn Assembly Over.

Pick and Place Accounting Calculations

Labor Cost = Labor Time * Labor Rate / Final Yield

Labor cost depends on the following:

• Labor time (see formula)

• Labor rate (specified by the machine property Labor Rate)

• Final yield (see Yields)

Labor Time = Process Time * Labor Time Standard

Labor time is the product of the following:

• Process time (see formula)

• Labor time standard: specified as the machine property Labor Time Standard. This multiplier is used to account for otherwise unaccounted for factors that affect labor time, such as operator fatigue or time spent by the operator for cleaning or maintenance.

Process Time = Operation Cycle Times + Unload Assembly Fixture Time

Process time is the sum of the following:

• Operation cycle times: sum of the cycle times of all child operations—see Clamp Operation Cycle Time Calculation, Load Operation Cycle Time Calculation, and Reorient Operation Cycle Time Calculation.

• Unload assembly fixture time: time to unload the finished assembly at the end of the assembly process. This is specified by the PSO Time to Unload the Assembly Fixture or looked up by component weight (sum of the weights of the assembly’s components) in the lookup table unloadWeldmentAllowance.

Amortized Batch Setup =

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

Amortized batch setup is the cost per part for setting up one production batch for the current process. Starting point VPEs assume that there is no batch setup associated with the Pick and Place process, but VPE administrators can configure the cost model to include setup cost (by setting the machine property Setup Time to a nonzero value). Setup cost depends on the following:

• Setup time (specified as the machine property Setup Time)

• Labor rate (specified by the machine property Labor Rate)

• Direct overhead rate (see Direct and Indirect Overhead)

• Batch size (specified in the Production Scenario screen of the Cost Guide)

Process Cycle Time Calculation

Cycle time for the whole process is given by the following formula:

Cycle Time = (Labor Time / Number of Operators) * Cycle Time Adjustment Factor

Cycle time depends on the following:

• Labor time (see Pick and Place Accounting Calculations)

• Number of operators: specified by the machine property Number of Operators or by the PSO Number of Operators. Note that cycle time is assumed to be inversely proportional to the number of operators.

This is the total number of operators performing pick and place tasks, including any Robotic Welding operators who perform pick and place tasks—see Robotic MIG Welding Process-level Options and Robotic TIG Welding Process-level Options for more information.

• Cycle time adjustment factor: specified by the cost model variable cycleTimeAdjustmentFactor; 1 in aPriori starting point VPEs. If you want to model an unbalanced, push assembly line, set cycleTimeAdjustmentFactor to a value greater than 1 in order to account for the cost of extra buffer capacity.

Note that indirect overhead depends on cycle time, while direct overhead depends on labor time. Cycle time contributes to part cost only via indirect overhead.