About Workload Balancing

Workload balancing provides an overview of workload across systems. Using a dynamic bar chart, you can balance operations from one system to another.

Workload balancing takes into account constraints on operations: product flows, time constraints, and constraints from implemented items.

This page discusses:

See Also
Balancing Workloads on a Selected System
Using Drifting Operations in Workload Balancing

Workload Balancing Panel

The Workload Balancing panel provides time and resource information about a system and lets you drag operations between child systems.

To open the panel, select a system and click Workload Balancing .

Hover over parts of the image to see the name for that section of the panel. Click any blue-bordered area for more information.

Bar ChartSystem Information TableBalancing Report

Tips:
  • The selected system can be the active system, a root system, or any other system. You can display the Workload Balancing panel for one system, then display another panel for another system. That way, you can easily compare the workloads of different systems at a glance.
  • When you close the panel, information such as length, width, and position is saved in a preference file (DELMSDWorkloadBalancingPreference.CATPreference) and retrieved the next time you open the panel. However, size and position information is based on the system reference name. Thus, persistency is not assured if the system is renamed or if different systems have the same reference name.

Bar Chart

The bar chart comprises the following elements:

Columns A column represents a leaf system in the selected system.

Systems are placed from left to right in the order of the product flow. For example, if the product flow order is S1 > S2 > S3, then S1 will be the leftmost column and S3 the rightmost one.

Note: Only General and Transformation systems are displayed.
Tip: You can specify operations or other systems as columns. For more information, see Balancing Workloads Using Operation Columns in Panel or Balancing Workloads Using System Columns in Panel.

Blocks A block represents an operation inside a leaf system.

A context menu is available on block to access Properties or to manage time analysis.

You can customize the block color in Me > Preferences > App Preferences > Simulation > Process Engineering Planning Structure > Balancing > Activity Bar.

Tip: When you select a block, the following colors provide additional information:
  • Light blue: The operation is selected.
  • Pink: The operation constrains the selected operation.
  • Orange: The operation is constrained by the selected operation.

Red horizontal lines A line represents the cycle time of a leaf system.

The maximum cycle time value among the leaf systems appears to left of the vertical axis line.

You can rearrange operations by dragging them:

  • Between columns
  • Between the bar chart and the tree
  • Between two bar chart views

This automatically updates the workload balancing and the position of the operations in the tree. Precedence constraints are automatically reconnected if possible.

For example, you can drag operations from the tree of a global workplan to the bar chart of a local line-balancing system, or between two separate bar charts for two separate factories.

System Information Table

The table under the bar chart provides the following information for each system:

Total Time The sum of the operation times.
Utilization Total Time * 100 / (Estimated Resources * Cycle Time)
Idle Time Estimated Resources * Cycle time – Total Time
Estimated resources (Total Time / Cycle Time) + 1

This represents the minimum number of resources required to realize the operations to respect the time cycle.

Cycle Time The cycle time of the root system.

Note: The context menu on the Parent System cell provides access to the following commands:
  • Product Configuration Display: Displays a panel that lets you:
    • Activate the product configuration display. You can then drag-and-drop operations across systems that have the same configuration. If the effectivities of the source and target systems are different, the drag-and-drop is impossible.
    • Display the product configuration synthesis. This option displays the system time (maximum, minimum and average) for all configurations, in a single column. You can display configurations that have no quantity specified (Manual Selection) or one of the production demands from the list. A tooltip and colors indicate the minimum, maximum and average system time.
  • Small Duration Mode : Shows operations with no defined duration.

    You can define the width and color of the blocks depends on the Small Duration options in Me > Preferences > App Preferences > Simulation > Process Engineering Planning Structure > Workload Balancing.

  • Actual Duration Mode: Closes Small Duration Mode and reverts back to default mode.
  • Export to XML: Exports the system information table as in XML file.

    For more information, see Exporting Workload Balancing Information to an XML File.

Balancing Report

To display the report, expand the section beneath the table.

The report contains the following information:

Number of Systems The number of systems in the workload balance table.
Number of Models The number of models in the workload balance table.

If the number of models is greater than one, or if any configuration is activated, then the rest of the fields in the expanded section will be non-applicable and displayed as Not Applicable.

Number of Configurations The number of configurations in the workload balance table.

If no configuration is activated, then the total number of available configurations is displayed. If any configuration is activated, then the total number of activated configurations is displayed.

Number of Estimated Resources The number of estimated resources in the workload balance table.
Number of Operations The number of operations in the workload balance table.
Total Time [s] The sum of all the total time of individual systems shown in the table.
Total Utilization [%] The percentage of total time divided by the sum of cycle times of individual systems.

Sequencing Mode

The sequencing mode determines how conflicts with parallel operations are resolved. This also determines the order of operations in the bar chart.

Parallel operations are defined by precedence constraints or product flows. Inside a system, two operations are considered parallel in one of the following situations:

  • They have no previous operation or next operation.
  • They are performed at the same time, and converge into the same next operation.

  • They are performed at the same time, and diverge from the same previous operation.

The following sequencing modes are available:

Precedence / Product Flow Mode Start Time / Tree Order Mode
Sequence order

Operations are sequenced based on precedence constraints.

In case of same precedence, they are sequenced based on product flows.

Operations are sequenced based on start time.

In case of same start time, their are sequenced based on tree order.

Supported links
  • Product flows
  • Precedence constraints
  • Product flows
  • Precedence constraints
  • Start-start links
  • End-end links
  • End-start links
Behavior

This mode requires a continuous, unidirectional flow of operations:

If no constraint exists between two operations, or in case of parallel operations, additional constraints are automatically created.

This mode does not create additional constraints.

You can select the sequencing mode in Me > Preferences > App Preferences > Simulation > Process Engineering Planning Structure > Workload Balancing.

Note: If you modify the tree order or switch sequencing mode, the bar chart is automatically updated. However, additional constraints created in Precedence / Product Flow mode are not deleted.

Value-Added Categories

If Time-Motion Study is installed, you can display valued-added categories in the Workload Balancing bar chart.

To do so select the Display value added categories from time analysis on system option in Me > Preferences > App Preferences > Simulation > Process Engineering Planning Structure > Workload Balancing.

In the Workload Balancing bar chart, a bar appears next to each column. When you hover over a bar, a tooltip displays values and percentages of value-added categories for the corresponding system. This information is also available for operations: when you hover over an operation, a tooltip displays values and percentages of value-added categories for the operation.

Note: Operations must have time analyses with enabled value-added categories. For more information, see the Time-Motion Study User's Guide.

You can customize colors of value added categories in Me > Preferences > App Preferences > Simulation > Process Engineering > Time-Motion Study > Value Added.

Drifting Operations

Process Engineers and Manufacturing Engineers in the Automotive industry balance operations to define sequences of operations on different systems (or stations). Multi-Cycle management allows specific sequences of operations to exceed the cycle time allocated to each system. In such cases, the operations of the sequence are able to drift and these drifting operations can be realized on several successive systems.

You can define a Multi-Cycle attribute on an operation in the Workload Balancing panel. Sometimes the end time of the operations exceeds the root system's cycle time. In this case, the operation and the following operations in the sequence are allowed to drift to other systems depending on the product flow.

The default color of drifting operations in the Workload Balancing panel is purple. You can customize the color in Me > Preferences > App Preferences > Simulation > Process Engineering Planning Structure > Workload Balancing.