Business & Operations
Lean Heijunka Pitch & Every Part Every Interval (EPEI) Level-Scheduling Formula
Calculate Toyota Production System Heijunka box Pitch = (Takt_Time * Pack_Qty) in minutes and mixed-model Every Part Every Interval EPEI = Total_Changeover_Min / (Available_Min - Daily_Run_Min) in days.
Pace material handlers by Heijunka Pitch and shrink batch sizes via SMED & EPEI!
Checking assembly progress once at the end of an 8-hour shift discovers problems 7 hours too late! In a Lean Heijunka (level-loaded) value stream, you multiply Takt Time (Available_Shift_Seconds / Daily_Customer_Demand) by standard container pack-out quantity Pack_Qty to get Heijunka Pitch—the exact heartbeat interval (in minutes) at which a water-spider material handler withdraws one finished tote and drops off the next kanban card! At 450 available min/day (27,000 s) and 900 units/day demand, Takt = 30 s/unit; with 20-unit totes, Heijunka Pitch = (30 * 20) / 60 = 10.0 minutes!
Across multiple SKU families sharing a press or molding cell, Every Part Every Interval (EPEI) measures how many days it takes to cycle through every part number once without exceeding shift capacity: EPEI = Total_Changeover_Time_All_SKUs / (Available_Daily_Time - Daily_Production_Run_Time)! With 135 minutes of total changeovers across all SKUs and 450 - 360 = 90 minutes/day of free changeover capacity, EPEI = 135 / 90 = 1.50 days—and cutting setup time in half via SMED (to 67.5 min) achieves "Every Part Every Day" (EPEI = 0.75 days)!
| Lean Level-Loading Metric | Shop-Floor Inputs | Formula | Result |
|---|---|---|---|
| Heijunka Pitch (Minutes) | 450 min/day, 900 units/day, Pack = 20 | (450 / 900) * 20 | 10.0 minutes per tote |
| Baseline Cell EPEI (Days) | Total Setup = 135 min, Free Cap = 90 min/d | 135 / (450 - 360) | 1.50 days |
| After 50% SMED Setup Cut | Total Setup = 67.5 min, Free Cap = 90 min/d | 67.5 / (450 - 360) | 0.75 days (Every Part Every Shift!) |
Heijunka Box Pitch Interval in Minutes = (Available_Min / Daily_Demand) * Pack_Qty
Computes Takt Time in minutes (B2 / B3) times standard container quantity B4.
=IF(OR(B2 <= 0, B3 <= 0, B4 <= 0), "Invalid Heijunka Inputs", ROUND((B2 / B3) * B4, 2))Every Part Every Interval EPEI in Days = Total_Changeover / (Available_Min - Run_Min)
Guards against overloaded cells where Daily_Run_Min B5 >= Available_Min B2 (leaving zero changeover capacity).
=IF(OR(B2 <= 0, B5 < 0, B6 < 0, B5 >= B2), "Overloaded Cell (Zero Changeover Capacity)", ROUND(B6 / (B2 - B5), 2))Try the example
Use the original values or change them to test your understanding.