Value Stream Mapping (VSM) Projection

EdgeNode compiles computable execution plans into standardized Lean Value Stream Maps (VSM). While process diagrams like BPMN model procedural routing and decision gateways, VSM focuses on flow economics—isolating the primary product family to calculate Value-Added Time (VAT), inventory waiting latency, Total Process Lead Time (PLT), and Process Cycle Efficiency (PCE).

High-Level VSM Mapping Overview

Value Stream Mapping represents the end-to-end journey of a single apex artifact. The rendering engine translates database cycles into operational process blocks, transaction latencies into inventory queue buffers, and pipeline triggers into informational flow vectors.

Core Lean Design Principles

1. One Product Family per Map: Standard Lean doctrine dictates isolating a single product family. In EdgeNode, the map isolates the plan's apex artifact—the root product that feeder streams converge upon.
2. Material vs. Information Flow Separation: All direct transactions along the primary stream represent material handoffs. Information flows are modeled strictly via inter-stream triggers, capturing upstream triggers without cluttering the material path.
3. Dual-Time Classification: Work durations are classified as Value-Added Time (VAT), whereas buffer latencies represent Non-Value-Added Time (NVAT).
4. Zero Branching & Lane Elimination: Unlike BPMN, VSM eliminates swimlanes and alternative decision diamonds. Operational roles are embedded directly into process data boxes, and only the priority-1 (happy path) trajectory is evaluated.

1. Apex Artifact Selection

In a complex multi-stream plan (e.g., an automobile consisting of engine, chassis, and electronics streams), EdgeNode identifies the apex value stream using two convergent heuristics:

Most Trigger Invocations

The stream that participates as the concerned across the highest number of pipelines rows (the point of maximum architectural convergence).

Fewest Production Units

The artifact generated in the lowest relative batch quantity (e.g., 1 final vehicle assembly versus hundreds of individual components).

2. Process Boxes & Inventory Queues

Each operational cycle within the apex stream is rendered as a square-cornered process box with a standardized Lean data block:

+-----------------------------------+
| Mount Engine                      |
+-----------------------------------+
| CT: 45 min                        |
| Role: Assembler                   |
| Art: assembly                     |
+-----------------------------------+

Alternating Grid Layout ($+2$ Stage Rhythm)

To preserve the standard Lean rhythm (Process $\rightarrow$ Inventory $\rightarrow$ Process), the layout engine advances stage ranks by 2 per hop:

• Even Columns ($0, 2, 4, \dots$): Reserved exclusively for Process Boxes.
• Odd Columns ($1, 3, 5, \dots$): Reserved for Inventory Triangles (△) representing queues with lead time latency (LT).

3. Sawtooth Timeline Ladder & Flow Efficiency

Beneath the process and queue grid, EdgeNode generates a continuous sawtooth timeline ladder that visually separates active work from waiting waste:

• Process Stage (Low / Green Segment): Rendered below each process column, labeled VAT: <duration>. If a stage contains parallel operations, the segment reflects $\max(\text{duration})$.
• Queue Stage (High / Red Segment): Rendered below each buffer column, labeled NVAT: <latency>. Reflects $\max(\text{latency})$ of the incoming material transaction.
• Diagonal Step Connectors: Sloped lines linking VAT and NVAT stages to produce the characteristic Lean sawtooth profile.

4. Mathematical Formulations

At the conclusion of the stream, a terminal summary card presents quantitative Lean flow metrics computed over the apex artifact's primary path:

Value-Added Time (Total VAT)

Total time actively spent performing transformations: $$ \text{Total VAT} = \sum_{c \in \text{Apex Cycles}} \text{duration}(c) $$

Total Process Lead Time (Total PLT)

Total elapsed door-to-door duration including intermediate inventory waiting latencies: $$ \text{Total PLT} = \text{Total VAT} + \sum_{t \in \text{Apex Priority-1 Flows}} \text{latency}(t) $$

Process Cycle Efficiency (PCE)

The percentage of total lead time that actually adds value to the customer: $$ \text{PCE} = \begin{cases} 100% & \text{if } \text{Total PLT} = 0 \ \left( \frac{\text{Total VAT}}{\text{Total PLT}} \right) \times 100% & \text{otherwise} \end{cases} $$

Worked Example: Automotive Assembly Line

Consider a manufacturing plan named car with an apex artifact of type assembly:

Apex Stream Data (assembly)

• Step 1 — Mount Engine: Duration = 45 min; Role = Assembler. Triggered by engine stream at state tested.
• Buffer 1: Latency = 3 hours.
• Step 2 — Mount Wheels: Duration = 30 min; Role = Assembler. Triggered by wheels stream at state balanced.
• Buffer 2: Latency = 2 hours.
• Step 3 — Final Inspect: Duration = 15 min; Role = QA.

Lean Economic Summary

• Total VAT: $45\,\text{min} + 30\,\text{min} + 15\,\text{min} = \mathbf{1\,\text{h}\;30\,\text{min}}$.
• Total NVAT: $3\,\text{h} + 2\,\text{h} = \mathbf{5\,\text{h}\;00\,\text{min}}$.
• Total Lead Time (PLT): $1\,\text{h}\;30\,\text{min} + 5\,\text{h}\;00\,\text{min} = \mathbf{6\,\text{h}\;30\,\text{min}}$.
• Process Cycle Efficiency (PCE): $\frac{1.5\,\text{h}}{6.5\,\text{h}} \times 100\% \approx \mathbf{23.08\%}$.

The artifact spends over 76% of its lifecycle waiting in non-value-adding inventory buffers, highlighting the primary target for Kaizen optimization.

Standards Comparison: VSM vs. BPMN vs. ArchiMate