How Much Slack Capacity Should Be Reserved?

When planning the toolset for a new factory, the amount of slack capacity reserved across all tools is an important variable. For a given start rate, reserving a large amount of slack capacity usually produces a good cycle time, but forces additional capital equipment purchases. To quantify these tradeoffs, use Factory Explorer®'s Fixed Cost & Cycle Time vs. Suggested Capacity Loading% Chart, shown below for Factory Explorer®'s sample Aspen model (based on data from SEMATECH's set4 testbed dataset). These results were generated using both capacity analysis and simulation.

Fixed Cost & Cycle Time vs. Suggested Capacity Loading% Chart
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Fixed Cost & Cycle Time vs. Suggested Capacity Loading% Chart, Aspen model. For this analysis, the start rate is held constant, and a minimum toolset is generated for each suggested capacity loading%. Reserving a large amount of slack capacity (setting the suggested capacity loading% to a low number) drives the total fixed cost up significantly, but ensures a low cycle time.

The Factory Explorer® Advantage

Since Factory Explorer® integrates capacity analysis and simulation, it can create the chart above with a single analysis run. Factory Explorer®'s capacity analysis engine generates a minimum toolset for each suggested capacity loading (a parameter you control at runtime). Then, using this toolset, Factory Explorer®'s simulation engine estimates the resulting cycle time. Factory Explorer®'s chart engine automatically creates the output chart. There is no need to maintain one model for capacity and one model for simulation. Factory Explorer® lets you analyze both with a single factory model, and offers cost analysis as well. Factory Explorer® is a complete decision support tool.

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