SiliciumHex FieldKit

Supply Chain · Map

Value Stream Mapping

Map every step of a product family from supplier to customer, with timelines, to expose waste and lead time.

  • Time2 h
  • FormatTeam
  • StageMap

Value Stream Mapping: what it is and why it works

Value stream mapping (VSM) is a one-page picture of how a single product family moves from raw material to the customer, drawn together with the information flow that triggers each step. The team walks the flow backward from the customer order, draws each process box, and attaches a data box with cycle time, changeover time, uptime, batch size and the inventory waiting in front of it. Inventory is converted into days of demand, which produces a timeline under the map: a lead-time ladder that sets total elapsed time against the few minutes or hours in which value is actually added.

The method works because it makes waiting visible. Most plants measure machine efficiency, but the customer experiences lead time, and lead time is dominated by queues between processes rather than by processing itself. A current-state map built from direct observation gives a shared fact base that departmental reports cannot, and the lead time to touch time ratio turns a vague sense of slowness into a number. VSM sits upstream of more focused tools: a supply flow diagram adds detail on ordering and handoffs, a bottleneck walk confirms where queues really form, and supply kaizen events implement the countermeasures the map identifies.

What you need

  • One product family chosen by shared routing, with its customer demand rate (units per day or week)
  • Permission and time to walk the shop floor and supplier receiving areas, following site safety rules
  • Observed cycle times, changeover times, batch sizes and uptime for each process step
  • Inventory counts between steps, taken on the same day to give a consistent snapshot
  • How orders, forecasts and schedules reach each process (ERP releases, kanban, phone, spreadsheet)

What you get

  • A current-state map with process boxes, data boxes, inventory triangles and information arrows
  • A lead-time ladder showing total lead time versus total value-added time
  • The three largest wastes, each located on the map rather than described in general terms
  • One countermeasure per waste, with an owner and a target date
  • A baseline against which a future-state map and later improvements can be measured

When to use it

When lead times are long and nobody sees the whole flow end to end.

How to do it, step by step

  1. Pick one product family with a representative flow.
  2. Walk the flow from customer order back to supplier, drawing every process box.
  3. Add data boxes: process time, wait time, inventory between steps, changeover.
  4. Compute total lead time versus total touch time — the ratio is your waste.
  5. Mark the three biggest wastes and design one countermeasure each.

Worked example: Hydraulic cylinder family at a component plant

Illustrative scenario — figures are realistic but not from a real company.

A mid-size manufacturer of hydraulic cylinders for agricultural equipment quoted six weeks to customers, while its cutting, welding, machining and painting steps took under four hours of combined processing per cylinder. On-time delivery had fallen below 80%, and the sales team was asking for more finished stock.

  1. The team chose the 2-inch and 2.5-inch bore cylinders, which share the same routing and make up about half of the volume at 120 units per day.
  2. Starting at shipping and moving upstream, they drew seven process boxes and counted inventory: 1,900 cut tubes, 1,100 welded bodies waiting for machining, and 700 painted units in the yard.
  3. Dividing each pile by daily demand gave 16, 9 and 6 days of stock. The lead-time ladder totaled 33 days against 3.6 hours of processing time.
  4. They marked three wastes: tube cutting in weekly batches, a weld-to-machining queue caused by a separate schedule for each department, and paint run in color campaigns.

Result. Countermeasures were daily cut lots, a single schedule point at final assembly with FIFO lanes upstream, and a paint sequence that rotated colors every shift. Three months later the same family showed 14 days of lead time and on-time delivery above 92%. The team's main lesson was that the machines were not slow; the work simply waited for them.

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Common pitfalls and how to avoid them

  • Mapping the whole plant or every product at once, which produces a wall of boxes and no decisions.Pick one product family with a common routing, map it well, and extend to other families later.
  • Building the map in a conference room from ERP routings and standard times.Walk the flow and count real inventory; standard data hides the queues and rework that the map exists to reveal.
  • Drawing only material flow and leaving the information flow blank.Show how every process learns what to make next; multiple schedule points are often the root cause of the queues.
  • Jumping to an idealized future state before the current state is agreed.Get the team to sign off on the current-state numbers first, then design a future state that addresses the three largest wastes.

Frequently asked questions

What is the difference between value stream mapping and process mapping?

A process map describes the steps and decisions of one process, often in detail. A value stream map covers a whole product family from supplier to customer at a higher level and adds a timeline, inventory between steps and the information flow that schedules work. VSM is meant for spotting where lead time is lost across departments; a process map is better for standardizing or troubleshooting one step.

How long does it take to create a value stream map?

A first current-state map for one product family can be drawn in a couple of hours if the team walks the flow together and collects data on the spot. Preparation takes longer when inventory counts or cycle times must be gathered across shifts. A future-state map and action plan usually need a second session, often a day or two for a complex flow.

How do you calculate lead time on a value stream map?

Convert each inventory pile into time by dividing the quantity by the daily customer demand, which gives days of stock. Add these waiting times across the flow and add the processing times of each step. The sum is total lead time; the processing times alone give value-added time. The ratio between them shows how much of the elapsed time is spent waiting.

Origin

Value stream mapping — Toyota production practice; codified in "Learning to See" (Rother & Shook, 1999).

Used in these playbooks

Lead time halving week 1 week

One week to find where time hides: map the flow, walk it, compress queues and lots — measure before and after.

  1. Value Stream Mapping
  2. Bottleneck Walk
  3. Lead Time Compression
  4. WIP Control
  5. Level Scheduling (Heijunka)

Related methods

More in “Map”

See the whole chain end to end before touching any part of it.