When value stream analysis is useful
- Lead times are long although processing time is short.
- Inventory and expediting rise at the same time.
- Priorities and information flows are unclear.
- A product family is to be reorganised before layout or automation decisions.
Consistent scope and data
The product family, start and end event, reference period and demand are defined first. Processing, changeover, waiting, inventory, quality losses and information triggers are measured on the same boundary. System data is reconciled with observation on the shop floor.
Approach
- Define product family, customer demand and boundary.
- Record the current material and information flow.
- Quantify work in progress, lead time, throughput and variability.
- Identify bottlenecks, loops, large batches and control losses.
- Design the future state and sequence measures by dependency.
Results and deliverables
- Current-state value stream with verified data
- Lead-time and inventory breakdown
- Future-state design and control principles
- Prioritised measures with owners and target metrics
- Interface to layout, material flow and implementation planning
Technical basis and limitations
Value stream analysis connects material and information flow. Processing time, waiting time and inventory are measured for the same product-family boundary. Little's Law provides a consistency check between work in progress, throughput and lead time; causes such as failures, priority rules or large batches are then investigated separately.
Digital event data can complement shop-floor observation but cannot replace verification of the real work or expert interpretation. Further reading: process mining in production and logistics.