Information Flow Symbols: Customer, Supplier, Scheduling, and Signals

Why Information Flow Makes or Breaks Your Value Stream

Picture this: a production team at a mid-sized automotive parts plant is hitting its daily output targets, yet finished goods inventory keeps piling up at the end of the line. The root cause, when finally uncovered, has nothing to do with machine speed or labor efficiency. The scheduling office is sending weekly batch orders to the shop floor based on a forecast that is already five days old, while the customer is calling in daily with last-minute changes. The material is flowing — but the information is not. This is exactly why Value Stream Mapping dedicates a full set of symbols to information flow. Without understanding how information moves, you only have half the picture.

The Core Information Flow Symbols and What They Represent

In VSM, information flow is drawn across the top half of the map, while material flow occupies the bottom. This deliberate layout reflects a fundamental Lean principle: production should be pulled by customer demand, not pushed by internal assumptions. Every symbol in the information flow family tells you something specific about how signals travel from customer to supplier and back through your scheduling system.

Customer and Supplier Icons

The Customer icon — typically a factory building symbol placed in the upper-right corner of the map — is your starting point. According to Kaizen Institute’s VSM methodology, you always start drawing with the customer. This is not a convention; it is a mindset. Every decision on your map should trace back to what the customer actually requires: their demand rate, their delivery frequency, their container quantities.

The Supplier icon mirrors the customer symbol and sits in the upper-left corner. It represents the external source of raw materials or components entering your value stream. Together, these two icons frame the entire map and remind the mapping team that value flows from supplier to customer — and that information must flow in the opposite direction, from customer demand back through your process to your suppliers.

Scheduling and Information Flow Arrows

Once your customer and supplier are placed, you need to show how information travels between them and your internal processes. VSM provides two distinct arrows for this purpose:

• Manual Information Flow Arrow: A straight arrow used to represent information communicated by paper, verbal instruction, or any non-electronic means — such as a daily schedule posted on a whiteboard or a paper work order handed to an operator.
• Electronic Information Flow Arrow: A lightning-bolt-style arrow indicating that information travels via electronic systems — ERP outputs, EDI transmissions, automated scheduling software, or email-based orders.

Distinguishing between these two is critical during a current-state mapping exercise. Teams often discover that their perceived “electronic” system actually triggers a cascade of manual re-entry steps downstream, each one introducing delay and potential error. Seeing both arrows on the same map makes this waste immediately visible.

Scheduling Signals: Kanban, Sequencer, and Leveling Box

The information flow family also includes a rich vocabulary for scheduling signals. These symbols describe how production authorization travels through the value stream:

• Production Kanban: A card or signal that authorizes a process to produce a specific quantity of a specific part. It is the trigger for replenishment in a pull system.
• Withdrawal Kanban (or Signal Kanban): Authorizes the movement of material from a supermarket to the consuming process. The Signal Kanban variant is typically used for batch replenishment at processes with significant changeover times.
• Kanban Arriving in Batches: Indicates that kanbans are collected and released together rather than one at a time — a common transitional state when moving from push to pull.
• Leveling Box (Heijunka Box): Represents a physical or logical device used to sequence and level the release of production kanbans over time. It is the scheduling heartbeat of a mature pull system.
• Sequencer: Similar to the leveling box, used to show that a defined sequence of production orders is being managed, often in mixed-model environments.
• Informal Scheduling: A symbol specifically used to highlight ad hoc, undocumented, or verbal scheduling decisions — a powerful visual cue that flags instability in the current state.

The presence of an Informal Scheduling icon on a current-state map is often one of the most impactful findings in a mapping workshop. It signals that the scheduling process depends on individual judgment rather than a defined system, making flow unpredictable and improvement difficult to sustain.

Practical Example: Applying Information Flow Symbols at Veltex Components

Veltex Components is a fictional manufacturer of plastic enclosures for consumer electronics, supplying a major assembly plant that requires daily shipments of three product variants. During a VSM workshop, the team placed the customer icon in the upper-right corner and immediately asked: “How does the customer’s demand reach us?” The answer revealed three separate channels: an EDI file sent once per week, a daily phone call from the customer’s logistics coordinator, and a monthly forecast spreadsheet emailed by the customer’s procurement team.

Three information streams, none of them synchronized. On the map, the team drew one Electronic Information Flow arrow for the EDI file pointing to the scheduling office, and two Manual Information Flow arrows for the phone calls and email, also pointing to the same scheduling office. The scheduling office then issued a Daily Schedule — shown with a straight manual arrow — to each production process on the shop floor.

The problem became immediately visible: the scheduling office was attempting to reconcile three conflicting signals and then translating them into daily push orders. There was no pull mechanism, no leveling, and no kanban in sight. The map showed exactly where information was being created, distorted, and lost.

In the future-state discussion, the team proposed replacing the three incoming streams with a single weekly EDI order and a daily call-off. Internally, they designed a simple Production Kanban loop between a finished goods supermarket and the final assembly process, governed by a Leveling Box that released kanbans in takt-aligned intervals. The Informal Scheduling icon that had appeared on the current-state map was replaced — in the future state — by a structured sequence tied directly to customer demand.

The difference between a map that informs decisions and one that simply documents reality lies in the accuracy and completeness of your information flow symbols. Every arrow, every scheduling icon, and every kanban signal is a question waiting to be answered.

Key Takeaways

• Always start with the customer: Place the customer icon first and work backward — information flow on your VSM must trace the path from customer demand through your scheduling system to your supplier.
• Distinguish manual from electronic information flow: Using the correct arrow type reveals hidden re-entry steps, delays, and communication breakdowns that are invisible in process data alone.
• Scheduling signals are not interchangeable: Production kanbans, withdrawal kanbans, signal kanbans, and informal scheduling each describe a fundamentally different relationship between demand and production authorization.
• The Informal Scheduling icon is a kaizen opportunity: Whenever you need to draw this symbol, you have identified a process that relies on human judgment instead of a defined system — a prime target for future-state redesign.
• Information flow enables or disables pull: A leveling box or sequencer on your future-state map is only meaningful if the upstream information flow feeding it is accurate, timely, and synchronized with actual customer demand.