Bottleneck sorting

The bottleneck sort function adjusts previous and subsequent operations with respect to the selected bottleneck operation, but preserves the current start of the bottleneck operation.

The function is used when operations on the bottleneck resource have been scheduled and the previous and subsequent operations should be scheduled with respect to the operations on the bottleneck resource.

Resolving bottlenecks by bottleneck sorting in ROB-EX is done by:

1. Selecting one or more operations in the gantt chart that are bottlenecks.
2. Right clicking on one of the selected operations.
3. Select “Bottleneck sort” from the right click menu
4. Select the bottleneck strategy and options to use in the Scheduling strategy window for bottleneck sort.
5. Press OK.

Using keyboard shortcuts for bottleneck sorting:

Select one or more operations in the gantt chart that are bottlenecks.

NOTE: Using keyboard shortcuts will not bring up the Scheduling strategy window for bottleneck scheduling.

Scheduling Strategy Window for Bottleneck Sort

Each time you do a bottleneck sort you are presented with the Scheduling strategy window for bottleneck sorting (this window is almost identical with the normal scheduling strategy window).

The settings in this window define how the bottleneck sort is performed.

Operations locked for bottleneck sorting

Operations

List of operation names of the selected operations that are locked for bottleneck sorting. The operation names are separated by semicolon, and would look like this:
Operation-1; Operation-2; Operation-3

Direction of Bottleneck sort

Option 2 is used to select the direction of the bottleneck sort.

Strategy

There are three ways of doing bottleneck sorting:

• Forward bottleneck (limited or unlimited capacity): Sort all subsequent operations after the bottleneck operations.
• Backward bottleneck (limited or unlimited capacity): Sort all previous operations before the bottleneck operations.
• Two-way bottleneck (limited or unlimited capacity): Do a backward bottleneck sort and then a forward bottleneck sort on the bottleneck operations.
  

Example:

In the example above the purple order has a broken constraint between operation R2045 and the subsequent operation R2046.

Once the broken constraint has been identified we need to establish if our bottleneck lies with the Mill 1 or the Subcontractor resource.

If it is “Mill 1” that is the bottleneck, use forward bottleneck sort from R2045.

If it is “Subcontractor” that is the bottleneck, use backward bottleneck sort from R2046.

Forward bottleneck sorting:
The function adjusts operations in the route, that are after the selected operations.

Select operation R2045, right click on the operation and select “Bottleneck sort”. Select “Forward bottleneck” as the scheduling strategy, and press “OK”.

The result is:

The two operations after operation R2045 have been rescheduled and placed as close to the operation as possible without breaking constraints.

Backward bottleneck sorting:
The function adjusts operations in the route, that are previous the selected operations.

Select operation R2046, right click on the operation and select “Bottleneck sort”. Select “Backward bottleneck” as the scheduling strategy, and press “OK”.

The result is:

The operation before operation R2046 have been rescheduled and placed as close to the operation as possible without breaking constraints.

Two-way bottleneck sorting:
Two-way bottleneck sorting is a combination of forward and backward bottleneck sorting.

First a backward bottleneck sort is performed on the selected bottleneck operations, and then a forward bottleneck sort is performed on the same operations.

Common Scheduling Settings for Bottleneck Sort

Common scheduling settings
See description of common settings from the normal Scheduling strategy window