Closing the Loop: Supplier Input, Raw Materials, and Full Map Integration

Learning Objectives

• Identify and correctly represent the supplier input and raw material flow on a current state VSM
• Explain how information flows from customer demand back through production planning to the supplier
• Integrate all map elements — customer, processes, inventory, information flows, and supplier — into a coherent current state map
• Calculate production lead time and value-added time using the timeline at the bottom of the map
• Recognize common issues and waste patterns that become visible once the full map is assembled

Imagine you are a plant manager standing in front of a half-finished VSM pinned to the wall. You have mapped your customer’s requirements on the right, traced each manufacturing process across the middle, and placed inventory triangles between each step. Yet something feels incomplete — the picture stops at your first process. Where does the raw material come from? Who tells the supplier what to deliver, and when? Without closing this loop, you are looking at a fragment, not a value stream. A partial map can highlight local inefficiencies, but it cannot reveal the full extent of lead time, the hidden buffers before your first operation, or the scheduling signals that ripple upstream. This lesson completes the picture by adding the supplier side, integrating the raw material input, and showing you how every element of the current state map connects into a single, readable story of flow — and waste.

Adding the Supplier: Raw Materials Enter the Value Stream

The VSM icon for an external source — a factory-style box — represents your supplier, and it belongs in the upper-left corner of the map, mirroring the customer icon in the upper-right. Together, they form the two anchors of your value stream. As defined by the Kaizen Institute framework, the value stream encompasses all activities currently required to transform raw materials and information into a finished product and service. That definition begins with raw materials, which means it begins with the supplier.

To complete this section of the map correctly, you need to capture the following data points:

• Material delivered: What physical input arrives — coils, components, sub-assemblies — and in what unit of measure?
• Delivery frequency: Does the supplier deliver daily, weekly, or on a variable schedule?
• Delivery method: Use the truck shipment icon with the appropriate frequency label to show this on the map.
• Raw material inventory: How many days of stock are held at the point of receipt? This becomes the first inventory triangle on your timeline.

In the reference example from the Kaizen Institute material, the supplier is Coils Plc, delivering steel coils. The raw material buffer at the start of the process holds 5 days of inventory. This single number already tells you something critical: before the first machine ever touches the material, five days of lead time are already locked in. That is waste — specifically, the waste of waiting and excess inventory — made visible by the map.

Closing the Information Loop: From Customer Demand to Supplier Schedule

A VSM is never just a map of material flow. It is equally a map of information flow, and the information loop must be closed just as rigorously as the material path. In a typical current state, information flows look like this:

1. The customer sends a forecast (often 90/60/30 days out) and a daily or weekly order to the producing company.
2. Production Planning, typically using an MRP or ERP system, receives this demand signal and generates production schedules.
3. Those schedules are pushed — often as weekly or monthly forecasts — back upstream to the supplier, who then ships raw material accordingly.
4. Simultaneously, Production Planning issues daily or weekly schedules to each individual process on the shop floor.

On the map, these flows are drawn as arrows across the top of the page. Electronic information flows use a lightning-bolt arrow; manual flows (fax, paper, verbal) use a straight arrow. In the Kaizen Institute example, a 6-week forecast is sent electronically to Coils Plc, while a daily order from the customer arrives at Production Planning. This contrast alone — a 6-week forecast going out versus a daily order coming in — is a red flag. It suggests the supplier is being scheduled on a batch-and-push logic that is disconnected from real customer demand. That tension is exactly what the current state map is designed to expose.

Each scheduling arrow from Production Planning down to a shop floor process should also be marked. When every process receives its own independent schedule from a central planning system, you have a classic push system — represented on the map by the push arrow icon between processes. This is a fundamental finding of the current state analysis and a key driver for future state design.

Assembling the Complete Map and Reading the Timeline

With the supplier added and the information loops drawn, you now have a complete current state map. Reading it end-to-end, from upper-left to lower-right, you should be able to trace both flows simultaneously: material moving from supplier through processes to the customer, and information moving from the customer back through planning to the supplier.

The final step in reading the map is building the timeline along the bottom. This is the most revealing calculation the VSM produces. The timeline alternates between two types of values:

• Inventory time (peaks): How long does material sit waiting — at the supplier buffer, between processes, in finished goods staging? These are the high points of the timeline.
• Process time (valleys): How long does a single unit spend actually being worked on at each process? These are the low points.

Summing all inventory times and process times gives you two critical metrics: Production Lead Time (the total time from raw material receipt to customer delivery) and Value-Added Time (the sum of process cycle times only). In the reference example, the production lead time runs to over 23 days, while value-added processing time amounts to just a few minutes. This ratio — days of lead time versus seconds or minutes of actual value — is the most powerful argument for change you will ever place in front of a leadership team.

Practical Example: Steelframe Components Ltd.

Consider Steelframe Components Ltd., a fictitious manufacturer of pressed steel brackets supplying the automotive sector. Their current state map, built by a cross-functional team over two days on the shop floor, revealed the following picture:

• Supplier MetalStrip AG delivers coils once per week based on a 30-day rolling forecast from MRP.
• Raw material inventory at the dock: 7 days.
• Four sequential processes — Stamping, Deburring, Welding, and Final Inspection — each receiving independent daily schedules from MRP (push arrows between every step).
• Inter-process inventory ranging from 1.5 to 4 days between each step.
• Finished goods staging: 2 days before shipment to the customer.

Total production lead time calculated from the timeline: 21.5 days. Total value-added time across all four processes: 187 seconds. The team had always believed their main problem was the stamping process changeover time. The completed map told a different story: 99.9% of the lead time was inventory waiting, not processing. The bottleneck was not speed — it was flow. This insight, visible only once the full map was assembled with supplier and customer in place, redirected the entire improvement programme.

Key Takeaways

• The supplier is the starting point of the value stream — always place the supplier icon in the upper-left and record the raw material inventory as the first data point on your timeline.
• Information flows must be mapped as rigorously as material flows — close the loop from customer demand through production planning to the supplier to reveal push-based scheduling and forecast misalignments.