Two‑Stage SMED — Batches, Transfer Batches, and Flow

💡 Idea: Smaller transfer batches let M2 start sooner—cutting lead time without changing product batch size.

Setup time M1 (min/batch) 30

Process time M1 (min/unit) 3.0

Setup time M2 (min/batch) 20

Process time M2 (min/unit) 4.0

Production batch (units) 40

Transfer batch M1→M2 (units) 10

Demand rate (units/hr) 12

Variability (0–1) 0.10

WIP holding cost ($/unit·hr) 0.50

Setup labor cost ($/min) 2.00

Late delivery penalty ($/unit short) 25

Revenue per unit ($) 60

Instructor notes

Hold the production batch constant. Shrink transfer batch to show faster first‑unit delivery and lower lead time.
Compare throughput (min of effective rates) vs. lead time (strongly improved by small transfer batches).
Show starvation/blocking: with M2 slower, buffer grows; with small transfer and fast M2, M2 starves unless balanced.

Setup M1 Processing M2 Processing Buffer (M1→M2) Demand

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Throughput ≈ min(M1 effective, M2 effective). Lead ≈ WIP / Throughput. Transfer batch cuts flow time to M2 even if throughput stays the same.

Self‑tests (open to view)

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