Tutorial ARENA (5/12)

Modeling Inventory and Production in Arena

Overview of the Model

• The discussion begins with modeling a problem in Arena, emphasizing that there is no single model but rather multiple efficient options.

• This example introduces two segments: one for inventory management and another for customer interactions, which are virtually linked through variables.

Handling Raw Materials

• Unlike previous simpler examples, this model ensures raw materials are always available by creating an entity that will be processed and recycled instead of disposed of.

Modules Breakdown

Create Module

• The Create module generates a single unit to start the process.

Advanced Process Modules

• The SIS (System Integration Services), Delay, and Release modules are separated; a new resource called "packaging process" is introduced.

Failure Management

• A random failure module is included, modeled with exponential time between failures averaging 200 minutes and normal repair times averaging 90 minutes with a standard deviation of 45 minutes.

Control Mechanisms

Hold Module Functionality

• The Hold module acts as a gatekeeper based on production status—allowing entities to pass only when production equals 1 (active).

Production Logic

• If production is at zero due to not reaching the reorder point (e.g., target stock of 500), it will resume once inventory drops below this threshold.

Packaging Process

• In the Delay module, packaging occurs within a uniform time frame ranging from 10 to 20 minutes.

Inventory Updates

• After processing, inventory updates occur by adding batch sizes. Using variables for batch size allows easier modifications later without extensive program changes.

Initial Conditions

• Initial conditions set include an inventory starting at 250 units and production initially at zero. Target stock remains at 500 for flexibility in future adjustments.

Decision Making in Inventory Management

Decide Module Functionality