How-To

Building a Process Flow in FlexSim

Creating a clear, structured process flow is the foundation of any effective simulation model. Whether you’re analyzing a manufacturing line, an airport operation, or a service workflow, the goal is the same: define the activities, connect them logically, allocate the right resources, and control the flow of events. This guide walks through the essential steps for building a robust process flow.

1. Define the Activities

Every process begins with a set of core activities. These are the tasks or operations that move work forward.

For a manufacturing example, typical activities might include:

Assemble Part
Inspect Quality
Package Product

Each activity should be placed in the process and configured with its relevant parameters—processing time, required resources, constraints, or other logic that reflects how the real system operates.

2. Establish the Flow Between Activities

Once the activities are defined, link them in the order they occur. These connections form the backbone of the model.

A simple sequence could look like:

Assemble Part → Inspect Quality → Package Product

More complex flows may include branching logic. For example:

If an item passes inspection → move to packaging
If it fails → route to rework or scrap

Decision points allow the model to reflect real-world uncertainty and variability.

3. Assign and Manage Resources

Activities rarely operate in isolation—they rely on people, equipment, or shared assets. Assign the required resources to each activity so the model understands what must be available for work to proceed.

Examples:

Assembly may require an operator and a machine
Inspection may require a specialized technician
Packaging may depend on the available workspace

Resource priority, availability, and utilization all influence system performance, and properly assigning them is key to uncovering bottlenecks and delays.

4. Integrate Events to Control the Flow

Events determine when activities start, when new work enters the system, and how the process responds to changes upstream or downstream.

Common event triggers include:

A new job arriving
A preceding activity completing
A shift change
A scheduled downtime

These events help coordinate the movement of work and ensure the process behaves like the real operation you're modeling.

Closing Thoughts

A strong process flow mirrors how work actually moves through a system. By defining activities clearly, connecting them thoughtfully, assigning the right resources, and controlling the flow with events, you lay the groundwork for meaningful simulation results—whether you're optimizing a production line, evaluating passenger flow at an airport, or improving a service operation.

Where should you allocate resources?

Simulation Modeling and Analysis 1. Scenario Testing * Create multiple scenarios in the simulation model. For instance, add or remove a machine or operator at different stations and observe the outcomes. 2. Key Metrics * Track lead time, throughput, and resource utilization for each scenario. * Compare scenarios to see which resource allocation

Which job should you schedule first? In what sequence?

Simulation Modeling and Analysis 1. Dispatching Rules * Program or set different scheduling heuristics (e.g., First-In-First-Out (FIFO), Earliest Due Date (EDD), Shortest Processing Time (SPT), etc.) in your FlexSim model. 2. Batch or Sequence Comparison * Experiment with various sequences in simulation (e.g., schedule high-priority orders first vs. regular jobs

Given the failure of a resource, how does this this affect your delivery time?

Simulation Modeling and Analysis 1. Downtime Modeling * Build probability distributions or schedules for resource downtime in your FlexSim model (e.g., Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR)). 2. Scenario Analysis * Run scenarios where a critical machine fails for a certain duration. Observe queue build-up, lead

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