Value Stream Redesign
Reduced idle time by 70% and cycle time by 15.5% on a precision component production line — through value stream analysis, bottleneck resolution, and a lean target state with Kanban, Heijunka, and continuous flow.
Standalone project.
The Problem
The production line for precision components had no production planning system and no demand forecasting beyond blanket orders. The primary processing step — the bottleneck — exceeded available working hours, forcing overtime and temporary labor while overloading the machines. An analog ordering process for production materials used hand-filled paper forms with a 20% rejection rate (illegible, incorrectly completed), causing late deliveries and idle time on the shop floor. Intermediate stock sat in chaotic mixed storage areas between process steps, with no FIFO enforcement and no visibility into machine availability. Pull control by individual workers led to high WIP, inconsistent cycle times, and irregular deliveries to the end customer. Total lead time was 1,507 minutes with 10 days of idle time across the value stream.
The Approach
Current-state analysis
- Value stream mapping
- To establish a shared factual baseline before proposing changes, the entire production flow was mapped ramp-to-ramp — from goods receipt of raw materials to outbound delivery note — using stopwatch time studies, ERP work-order data (full year), and on-site Gemba walks with production staff and management. Idle times were calculated as the average delta between completion and start dates across all work orders for the period.
- Product family selection
- The highest-revenue product group was identified as the A/X category — roughly 50% of revenue with stable demand from blanket orders. The highest-volume variant was selected for the value stream, representing a product family where all variants share the same manufacturing process and material flow despite mechanical diversity.
- Bottleneck identification
- The primary processing step was identified as the constraint: its cycle time exceeded available working time, requiring overtime or temporary staff and preventing maintenance windows. To focus effort where it would actually move throughput, a cost–benefit matrix of all identified issues guided prioritization — high-cost, low-benefit items like implementing a full production planning system were excluded from the target state in favor of measures that could be implemented and stabilized incrementally.
Target-state design
- Bottleneck relief
- To create a capacity buffer without adding labor, a third machine was specified to increase throughput at the constraint — eliminating overtime and machine overload within available working hours. A specialized welding machine was procured to cut welding cycle time by 50%.
- Continuous flow with FIFO lanes
- Chaotic intermediate storage areas were replaced with FIFO lanes between process steps. Where takt alignment was possible, continuous flow was established gated by signal Kanban at the bottleneck rate. The welding and straightening steps were parallelized.
- Supermarket pull system
- Because components cure overnight — a natural decoupling point in the flow — a supermarket pull system was introduced at the curing stage. Production Kanban cards control work order release into the second segment, allowing priority changes on short notice without disrupting flow.
- Production levelling (Heijunka)
- To smooth the volume fluctuations caused by mixing make-to-stock and make-to-order, the production mix was levelled across all product families. Customer deliveries were restructured to weekly fixed quantities, aligning production takt to customer takt.
- Material supply via Kanban
- To eliminate the 20% form-rejection rate and the delays it caused, the analog paper-based ordering process was replaced with a combination of ERP-based MIN/MAX replenishment and Kanban. Specialized materials are commissioned per work order, while sub-materials and packaging are commissioned once per week and staged directly in the production warehouse without an intermediate stop in the main warehouse. Lot sizes were revised to match optimal production batch sizes and reduce lead times.
Implementation planning
- Phased rollout
- To avoid disrupting a running production line with simultaneous changes, an 11-step action plan followed a continuous improvement (CIP) approach — each measure implemented and stabilized before the next begins. Responsibilities were assigned across sales, purchasing, production, logistics, and engineering, with a kick-off to detailed planning cycle of roughly three months.
Architecture
The Result
Idle time reduction
70% — from 10 days to 3 days across the value stream
Lead time reduction
15.5% — from 1,507 to 1,274 minutes per lot
Cycle time reduction
15.5% — from 75.4 to 63.7 minutes per piece
Bottleneck capacity
Third machine at the constraint creates a capacity buffer, eliminating overtime and machine overload
Process consolidation
9 discrete steps consolidated into 6 workstations through parallelization and merging