Business & Operations
Drum-Buffer-Rope (DBR) Buffer Penetration % & TOC Green/Yellow/Red Expedite Priority
Calculate Theory of Constraints (TOC) time-buffer consumption percentage 100 * (Buffer_Hours - Remaining_Hours) / Buffer_Hours and classify work orders into Region I Green (<33.3%), Region II Yellow (33.3%–66.7%), or Region III Red (>66.7%) expedite zones.
Prioritize shop-floor expediting by TOC Buffer Penetration—not local machine efficiency!
In Eliyahu Goldratt's Theory of Constraints (TOC) Drum-Buffer-Rope (DBR) scheduling, the Drum (system bottleneck) sets the master schedule, the Rope gates raw-material release exactly Buffer_Hours ahead of the Drum (or customer ship date), and the Time Buffer absorbs Murphy's Law upstream disruptions so the Drum never starves!
Buffer Management replaces chaotic due-date firefighting with a single metric—Buffer Penetration % = 100 * (Buffer_Hours - Remaining_Hours_to_Due) / Buffer_Hours! Dividing a 24-hour constraint buffer into three equal 1/3 zones: Region I Green (< 33.3% consumed, >= 16 hr remaining) means hands-off normal flow; Region II Yellow (33.3% to 66.7% consumed) triggers upstream tracking/watch; and Region III Red (> 66.7% consumed, e.g., only 6 hr left on an unarrived order -> 75.0% penetration!) triggers immediate shop-floor expediting!
| Work Order (24 hr Constraint Buffer) | Hours Remaining to Drum | Buffer Penetration % | TOC Buffer Management Zone |
|---|---|---|---|
| WO-101 (Upstream Smooth) | 18 hr remaining | 25.0% consumed | Green Zone (<33.3%: Do Not Expedite) |
| WO-102 (Delayed at Prep) | 12 hr remaining | 50.0% consumed | Yellow Zone (33.3%-66.7%: Locate & Watch) |
| WO-103 (Machine Breakdown) | 6 hr remaining | 75.0% consumed | Red Zone (>66.7%: Expedite Immediately!) |
| WO-104 (Past Drum Schedule!) | -3 hr remaining | 112.5% consumed | Black / Late (>100%: Buffer Exhausted!) |
TOC Time-Buffer Penetration Percentage (%)
Computes 100 * (Total_Buffer_Hours - Remaining_Hours) / Total_Buffer_Hours for positive buffer B2.
=IF(B2 <= 0, "Invalid Buffer Size", ROUND(100 * (B2 - B3) / B2, 1))Three-Zone TOC Buffer Management Priority Status
Classifies buffer penetration into Green (<= 1/3), Yellow (<= 2/3), Red (<= 100%), or Late (> 100%).
=IF(B2 <= 0, "Invalid Buffer Size", IF(((B2 - B3) / B2) > 1, "Black Zone (>100%: Late!)", IF(((B2 - B3) / B2) > (2 / 3), "Red Zone (>66.7%: Expedite!)", IF(((B2 - B3) / B2) > (1 / 3), "Yellow Zone (Watch)", "Green Zone (On Track)"))))Try the example
Use the original values or change them to test your understanding.