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Example: Production Bottleneck — Manufacturing Throughput

Problem

"Our factory produces 100 units per day but orders require 150. We have 5 production stages. Everyone seems busy. Adding overtime didn't help much. We're losing orders and customers are frustrated."

Tools Used: /toc:five-steps + /toc:dbr

Five Focusing Steps Analysis

Step 1: IDENTIFY

Stage Capacity (units/day) Utilization Queue (units)
Cutting 180 56% 0
Welding 110 91% 12
Painting 100 100% 35
Assembly 160 63% 0
Testing 200 50% 0

Constraint identified: Painting (Stage 3)

  • Capacity: 100 units/day (lowest)
  • Utilization: 100% (maxed out)
  • Queue: 35 units waiting (largest backlog)

Step 2: EXPLOIT

Current waste at the painting station:

  • 45 minutes/day lost to color changeovers (3 changeovers × 15 min)
  • 8% of painted items need rework (sent back through painting)
  • 30-minute lunch break where the booth is idle

Exploitation actions (zero investment):

Action Time Recovered Units Gained
Batch by color to reduce changeovers (3→1/day) +30 min/day +6 units
Quality gate BEFORE painting (catch defects earlier) +8% capacity +8 units
Stagger lunch breaks (painter 2 covers) +30 min/day +6 units
Total +20 units/day

New throughput: 120 units/day (+20%)

Step 3: SUBORDINATE

Stage Current Behavior New Behavior
Cutting Produces 180/day (piles up inventory) Produce only 120/day (match painting)
Welding Processes in any order Prioritize by painting schedule
Assembly Waits for painted parts Buffer: maintain 4-hour supply of painted parts
Testing Tests as items arrive No change (excess capacity)

Stop measuring: Individual stage efficiency Start measuring: System throughput (units shipped per day)

Step 4: ELEVATE (if 120/day is insufficient)

Option Cost Capacity Gain Throughput
Add night shift for painting $4K/month +50 units/day 150/day
Second paint booth $80K one-time +100 units/day 200/day
Outsource painting overflow $5/unit +30 units/day 150/day

Recommended: Add night shift first (low investment, quick). Second booth only if demand sustains 150+.

Step 5: REPEAT

After adding night shift (painting capacity → 150/day):

  • New constraint likely moves to Welding (capacity 110)
  • Plan: Apply Five Steps to Welding next

Drum-Buffer-Rope Design

graph LR
    ROPE["🪢 ROPE<br/>Release: 120/day"]
    CUT["Cutting<br/>Cap: 180"]
    WELD["Welding<br/>Cap: 110"]
    BUF["⏱️ BUFFER<br/>4 hours"]
    DRUM["🥁 DRUM<br/>Painting<br/>Cap: 120"]
    ASM["Assembly<br/>Cap: 160"]
    SBUF["⏱️ SHIP BUF<br/>2 hours"]
    SHIP["Shipping"]

    ROPE --> CUT --> WELD --> BUF --> DRUM --> ASM --> SBUF --> SHIP
    DRUM -.->|"signal"| ROPE

    style DRUM fill:#d63031,color:#fff,stroke-width:3px
    style BUF fill:#fdcb6e,color:#000
    style SBUF fill:#fdcb6e,color:#000
    style ROPE fill:#00b894,color:#fff
Loading

Scheduling Rules

  1. Release: Start new work only when Painting signals capacity (120 units/day max)
  2. WIP Cap: Maximum 60 units in the system at any time
  3. Priority: If buffer is red (>67% consumed), expedite at all non-constraints
  4. Color batching: Group painting orders by color — max 1 changeover per day

Buffer Management

Constraint Buffer: [████████████░░░░] 75% remaining (GREEN)
Shipping Buffer:   [██████████░░░░░░] 62% remaining (GREEN)

WIP: 42 units (cap: 60)
Throughput: 118 units/day (target: 120)
On-time delivery: 94% (was 71%)

Results Summary

Metric Before After Exploit After Subordinate
Throughput 100/day 120/day 120/day
Lead time 8 days 5 days 3 days
WIP 120 units 80 units 60 units
On-time delivery 71% 85% 94%
Overtime cost $6K/month $0 $0
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