Bottleneck Scheduling

Key Concepts

It is important to identify bottlenecks in manufacturing to improve the efficiency of production. PlanetTogether offers multiple options to identify bottlenecks and alleviate their impact on the production schedule.

Bottlenecks

In PlanetTogether, an activity is considered a bottleneck if it is late and has no predecessors that are late. This activity must be moved to an earlier time if the job and its successors are to be on time.

  • Resource bottleneck: This is any resource whose capacity is less than the demand placed on it. When attempting to produce more than a resource is capable, there is usually an accumulation of work-in-progress or inventory items. This can cause downstream operations requiring those items to be late as well.
    • Bottleneck percent: This represents the resource's scheduled activities that are capacity bottlenecked. This information is found in the "Analysis" tab of the Resource Options dialog.
  • Material bottleneck: This is an activity where the required materials are not available early enough for it to finish on time and is causing downstream activities to be late as well.

Identifying Bottlenecks

You can identify resource bottlenecks by looking at each resource's Performance Report. Thie report compares the actual time and quantities needed to complete the operation to the expected values. A performance above 100% means that the resource is running slow and is a potential bottleneck. This report is accessed from the Gantt chart under Reports | Resource Performance.

The activity blocks on the Gantt chart can also display visual information to identify material bottlenecks and capacity bottlenecks. Under the "Timing" segment of the block labels, material bottlenecks will be highlighted in bright pink while capacity bottlenecks will be highlighted in red.

Bottleneck Remediation

Bottleneck scheduling is a method in which the system will schedule the bottleneck operation at a time that will not make the job late, then will schedule predecessor and successor operations around it. This is useful to:

  • Protect critical resources
  • Buffer against variability in production, shipping, and purchasing

After identifying resource bottlenecks, these may be scheduled for maintenance to increase their production efficiency.

Drum-Buffer-Rope (DBR) Scheduling

Another alternative is to use Drum-Buffer-Rope scheduling to prevent the accumulation of work-in-progress items and protect the capacity-constrained resource. In DBR scheduling, the capacity-constrained resource (or "bottleneck") is the Drum. A Buffer can be placed in front of the Drum resource to avoid starving it and maximize the throughput.

Additional information on setting up DBR scheduling in PlanetTogether can be found here.

  • To use this type of scheduling, select the Drum-Budder-Rope release rule from the Optimize button drop-down menu.

                         

  • Then, double-click on your drum resource to open the Resource dialog. Check the “Drum”
    checkbox in the advanced rules and specify the buffer span.