Value Stream Mapping and Process Analysis
This section covers value stream mapping and process analysis. The exam tests whether you can map a value stream door-to-door, separate material from information flow, calculate lead time and process cycle efficiency, and convert a current state into an owned future-state plan.
Mapping rules
- Map one product family from supplier to customer, with the customer at upper right.
- Show information flow (forecasts, schedules, MRP, expediting), not only process boxes.
- Record cycle time, changeover, uptime, batch size, and inventory at each step.
- Draw the timeline ladder: inventory days above, processing time below.
Takt time = available time ÷ customer demand. Compare takt with each cycle time to expose the constraint; never confuse takt with cycle time.
Worked example
A claims process has five steps with cycle times of 12, 8, 20, 6, and 4 minutes, and inventories of 600, 300, 900, and 200 claims between them. Demand is 400 claims per 480-minute shift, so takt = 1.2 minutes. Total work content is 50 minutes, but the 20-minute step limits output to 24 claims per shift unless parallel capacity is added. Total work in process is 2,000 claims; lead time ≈ 2,000 ÷ 24 ≈ 83 shifts. The future state balances the 20-minute step to takt, replaces push with FIFO lanes and a pull signal, and sets a value stream plan with owners and dates.
Traps that cost marks
- Mapping everything, so the map becomes unreadable.
- Mixing product families with different routings.
- Reporting cycle time as lead time, or omitting queue time from the timeline.
- Producing a future-state map with no kaizen bursts, owners, or review cadence.