Value Stream Mapping Symbols: Rother/Shook and Erlach Compared
Value stream maps use a fixed set of symbols so that any lean practitioner can read them without a legend. The two common schools differ in details; ValueStreamMapping.app offers the superset of both symbol sets.
Material flow
- Process box: one process step with a data box (cycle time, changeover time, uptime, scrap rate, batch size, operators, shifts, EPEI).
- Inventory (triangle with "I"): uncontrolled inventory between two processes, given in pieces; the tool converts it into inventory days.
- Supermarket: a controlled pull inventory from which the downstream process withdraws and which is replenished by kanban.
- FIFO lane: links two processes with a capped quantity in a fixed sequence.
- Safety stock: a buffer held on purpose against disruptions, for a limited time.
- Push arrow (striped): material is pushed downstream regardless of demand. Pull arrow: the downstream process withdraws what it needs.
- Shipment (truck, milk run, rail): external delivery with a frequency.
- Tugger route (mizusumashi): internal milk run between supermarket and line, with loop time and utilization.
Information flow
- Production control (box at the top): the ERP or MRP system that receives forecasts and orders.
- Business process (Erlach): order processing, production planning, material planning, each with a duration in working days.
- Manual information flow (straight arrow) and electronic information flow (lightning arrow).
- Production kanban, withdrawal kanban and signal kanban: cards that trigger production or withdrawal.
- Kanban post and heijunka box: collection point for cards, and the leveling box at the pacemaker.
- "Go see" (glasses): scheduling by visual check instead of by system.
Notes and timeline
The kaizen burst marks an improvement idea where it takes effect. In the editor it carries an owner, a due date and a status, which turns it into an action item.
The timeline (lead time ladder) at the bottom compares waiting times (top) with processing times (bottom). Their totals are the production lead time and the processing time.
Rother/Shook or Erlach?
The American school (Lean Enterprise Institute) is used worldwide and uses English abbreviations in the data box (C/T, C/O, uptime). The German Erlach notation adds business processes, transports and a stricter terminology, and it is the basis of many university courses in German-speaking countries.
For US readers and international sites, Rother/Shook is the default. Choose the Erlach set if your team was trained in it or you work with German plants. In the editor you can switch the symbol set at any time, and the data boxes are labeled to match.
Practice in the editor
In the demo, switch the symbol set between Superset, Erlach and Rother/Shook and watch the palette and the data boxes change.
Open the template in the editor Start blankFrequently asked questions
What does the triangle mean in value stream mapping?
The triangle with the letter I (inventory) is inventory between two processes. The piece count is written below it, and the inventory days follow from that.
What is the difference between a supermarket and a FIFO lane?
A supermarket holds set quantities per variant and is replenished by kanban; the downstream process takes what it needs. A FIFO lane links two processes with a capped quantity in a fixed sequence, with no choice of variant.
What does EPEI stand for?
Every Part Every Interval: the period in which every product of the family is produced once. The shorter it is, the smaller the batches and inventories.