📋 Case Study

Automotive Tier-1 Supplier Line Balancing Optimization

Labor cost overrun due to unbalanced station cycle times and high overtime

🏗️ Project Overview

New EV battery module assembly line in Michigan

🎯 Challenge

Labor cost overrun due to unbalanced station cycle times and high overtime

🔧 Design Approach

Time-motion study + takt time alignment using SMED principles and cross-training matrix

📐 Design Diagram

Time-Motion Study(Baseline CT)Takt Alignmentσ/TT = 23.6%SMED + Cross-TrainingMatrix ImplementedChallengeLabor Cost/Unit: $42.70(Overtime Driven)Optimized OutputCycle Time Variance ↓Key MetricsTakt Time: 82 secAvg CT: 79.2 sec (±19.4)

AI-generated project design illustration

📐 Key Calculations

Labor Cost per Unit

(Overtime Hours × Overtime Rate) / Units
Result: $42.70
Identified $18.30/unit excess cost

Takt Time Variance

σ(Cycle Times)/Takt
Result: 23.6%
Triggered bottleneck redesign

📊 Results

19% reduction in direct labor cost/unit, 31% decrease in overtime hours, 99.2% first-pass yield achieved

💡 Lessons Learned

  • Cycle time standardization must precede cost modeling
  • Cross-training ROI requires 6-month horizon
  • Overtime premium distorts true labor cost attribution

Key Takeaways

  • 1Cycle time standardization must precede cost modeling
  • 2Cross-training ROI requires 6-month horizon
  • 3Overtime premium distorts true labor cost attribution