Batch Size Showdown — How setups & batches shape flow

💡 Idea: Big batches amortize setups but balloon WIP & lead time. SMED shrinks setups so small batches win.
Instructor notes
  • Challenge: Hit ≥ demand with the lowest WIP. What batch & setup combo wins?
  • Show SMED: Reduce setup and drop batch—watch lead time fall and WIP shrink per Little’s Law.
  • Discuss trade‑offs: due‑date performance vs. utilization vs. changeover effort.
Setup Processing Demand

Effective Rate

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Meets Demand?

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Cycle per Batch

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Lead Time (≈)

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Avg WIP (≈)

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Utilization

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Lead ≈ WIP / Throughput (Little’s Law). Effective rate accounts for setup losses: Rate = batch / (setup + batch·tunit).