Assembling Smartphones: Takt Time Ã¢â€° Cycle Time? Custom Case Solution & Analysis

Evidence Brief: Operations and Financial Data

Financial Metrics

Labor Cost: 12.50 USD per hour per worker.
Unit Revenue: 450.00 USD per smartphone.
Material Cost: 210.00 USD per unit.
Overhead Allocation: 45.00 USD per unit at standard capacity.
Cost of Idle Time: 0.21 USD per minute per idle station.
Inventory Carrying Cost: 18 percent annual rate.

Operational Facts

Available Time: 480 minutes per shift, including two 15-minute breaks.
Net Production Time: 450 minutes per shift.
Market Demand: 450 units per day.
Calculated Takt Time: 1.0 minute per unit.
Total Work Content: 18.4 minutes of manual assembly across all steps.
Current Cycle Time: 1.2 minutes at the bottleneck station.
Number of Stations: 20 active assembly points.
Defect Rate: 3.4 percent at final testing.

Stakeholder Positions

Plant Manager: Focused on meeting daily volume targets regardless of overtime costs.
Line Supervisor: Concerned about worker fatigue and repetitive motion injuries at higher speeds.
Finance Director: Prioritizing reduction in Work in Process inventory to improve cash flow.
Quality Lead: Opposed to cycle time reductions that might compromise inspection thoroughness.

Information Gaps

Changeover Time: The case does not specify time required to switch between smartphone models.
Labor Turnover: Data on worker experience levels and training duration is absent.
Supplier Reliability: Component arrival frequency and buffer stock levels are not provided.

Strategic Analysis: Production Synchronization

Core Strategic Question

The primary challenge is the misalignment between the 1.0-minute takt time required by the market and the 1.2-minute cycle time limited by the bottleneck.
The organization must decide whether to expand capacity through additional labor or optimize existing station configurations to prevent lost sales.

Structural Analysis

Applying the Theory of Constraints reveals that the assembly line is currently demand-constrained in theory but supply-constrained in practice due to the bottleneck. Little Law indicates that the current Work in Process is higher than necessary because of the cycle time mismatch, leading to accumulation before the slowest station.

Strategic Options

Option 1: Line Re-balancing and Task Redistribution

Rationale: Reduce cycle time to 0.95 minutes by redistributing 0.25 minutes of work from the bottleneck to underutilized stations.
Trade-offs: Requires significant retraining and may increase the risk of errors during the transition period.
Resource Requirements: Industrial engineering team for 40 hours; 2 days of worker cross-training.

Option 2: Parallel Bottleneck Processing

Rationale: Duplicate the bottleneck station to effectively halve its cycle time contribution.
Trade-offs: Increases capital expenditure and requires additional floor space.
Resource Requirements: One additional workstation setup and one full-time equivalent worker.

Option 3: Demand-Matched Overtime

Rationale: Maintain current cycle time and use 90 minutes of daily overtime to meet the 450-unit target.
Trade-offs: High labor cost and long-term worker burnout; does not solve the underlying inefficiency.
Resource Requirements: 15 percent increase in daily labor budget.

Preliminary Recommendation

Pursue Option 1. Re-balancing the line to achieve a cycle time below the takt time is the only path that improves unit economics without increasing fixed costs. This alignment ensures the factory meets market demand within standard working hours.

Implementation Roadmap: Operational Execution

Critical Path

Week 1: Conduct granular time and motion studies for all 20 stations to identify micro-tasks.
Week 2: Design the new line configuration with a target cycle time of 0.95 minutes.
Week 3: Execute cross-training for workers at the bottleneck and adjacent stations.
Week 4: Implement the new configuration during a weekend shift to minimize production loss.
Week 5: Monitor defect rates and throughput, adjusting task allocation as needed.

Key Constraints

Worker Skill Variance: Not all assembly staff possess the manual dexterity required for the most complex tasks.
Physical Layout: The fixed position of specialized testing equipment limits the ability to move certain tasks.

Risk-Adjusted Implementation Strategy

To mitigate the risk of a production dip during the transition, the plant will build a three-day finished goods buffer before implementing the new line balance. If the defect rate exceeds 5 percent in the first week, the line will temporarily revert to the 1.2-minute cycle time while the engineering team troubleshoots the specific task hand-offs.

Executive Review and BLUF

Bottom Line Up Front

The assembly line is failing to meet market demand because the bottleneck cycle time of 1.2 minutes exceeds the required takt time of 1.0 minute. This gap results in a daily shortfall of 75 units, representing 33,750 USD in missed revenue per shift. The recommendation is to re-balance the line to a 0.95-minute cycle time. This action eliminates the need for expensive overtime and aligns production capacity with market requirements. Immediate execution is required to prevent market share loss to competitors with higher fulfillment rates.

Dangerous Assumption

The analysis assumes that work content is perfectly divisible. In reality, smartphone assembly involves discrete tasks that cannot always be split between workers without increasing the total work content due to additional handling time.

Unaddressed Risks

Supply Chain Volatility: Probability High, Consequence High. If component delivery is inconsistent, achieving a 0.95-minute cycle time will lead to frequent line stops.
Worker Resistance: Probability Medium, Consequence Medium. Increasing the pace of work to match takt time may lead to higher turnover or labor disputes.

Unconsidered Alternative

The team did not evaluate the outsourcing of sub-assembly tasks. Moving the first 4 minutes of work content to a third-party vendor would reduce the internal total work content to 14.4 minutes, allowing for a 15-station line with a 0.96-minute cycle time, significantly reducing internal headcount.