Chapter 3: Modeling in Plant Simulation – Material Flow (II)
Modeling material flow – Point-oriented and length-oriented objects
MUs are processed, transported and stored by material flow objects. Generally, we can differentiate between two categories of material flow objects: point-oriented and length-oriented material flow objects.
Point-oriented material flow objects do not take into account the physical length or dimension. MUs are processed or stored in these objects on a fixed location for a given time. Material flow objects that belong in this category are:
- SingleProc is a single station that can process one MU at a time. It receives an MU from its predecessor object and releases the MU after the defined set-up and processing times to its successor object.
- ParallelProc is a station that can process several MUs at a time. ParallelProc corresponds to two or more SingleProc stations that receive the same parts from the same predecessor.
- AssemblyStation assembles MUs received from multiple predecessor objects together. You can create an Assembly Table to define the number of parts required from each predecessor to create the final product.
- DismantleStation removes assembled parts from the main MUs.
- Buffer can temporarily hold MUs from the predecessor object when the successor object is unavailable to receive them. Buffer dimensioning is one of the main use cases for simulation study, as a sufficient buffer dimension is required to prevent production stop. A buffer can either be a queue (FIFO – First In First Out) or a stack (LIFO – Last In First Out).
- FlowControl is used to model different strategies for distributing and merging the flow of materials from one or multiple predecessor objects to one or multiple successor objects.
On the other hand, length-oriented material flow objects take into account their length and dimension as well as the length and dimension of the MUs that pass through them. Length-oriented material flow objects use the length, dimension, and speed information to determine the time required to pass on the MUs to the successor. Material flow objects that belong in this category are:
- Line is used to model a conveyor system that transports MUs along its entire length with a constant speed. An MU that is currently transported along the Line cannot pass another MU in front of it.
- Angular converter connects two Line objects and changes the conveying direction of the MUs accordingly. It can only move one MU at a time.
- Turnplate is used to model a rotating platform. It can connect two or more Line objects and ensure the uniform orientation of the MUs leaving it by rotating them.