Rescheduling All Orders—Key Exercises

IMPORTANT
It is extremely important that you set up and work within the CBS training site. If you work within any other site, you will not be able to access a CBS server. To simplify data entry, select the CBS site as your default site on the Sites per User window. Also, to keep your data separate from that of other users, be sure to name all data using your initials as the prefix.

Basic Data Setup

Overview of Constraint Based Scheduling Data

Purpose: The purpose of this exercise is to create the required data used in the Constraint Based Scheduling (CBS) exercises. This sets up data for your site that needs to be done only once for all CBS exercises.

  1. If you have not done so already, set up your site so that it includes all the CBS required data.

General exercise for Overview of Constraint Based Scheduling Data

Main Exercises

Sorting by Earliest Due Date

Purpose: The purpose of this exercise is to demonstrate how sorting by earliest due date changes the sequence of the schedule.

Windows:
Simulation Client

Note: Before beginning this exercise, you will need to create four new shop orders for Part XX-250-GEAR20, as listed in the table below.

Shop Order Schedule Direction Earliest Start Date Need Date Lot Size
XX-SO4 Forward Second Monday from today  The Thursday following the second Monday 15
XX-SO5 Forward Second Monday from today The Saturday following the second Monday 100
XX-SO6 Forward Second Monday from today The Wednesday following the second Monday 10
XX-SO7 Forward Second Monday from today The third Monday from today 5
  1. Reopen or refresh the Simulation Client.
  2. Load the All Shop Orders scheduling scenario. All shop orders are plotted in the object table area of the Gantt Overview pane.
  3. Scale the Gantt chart to display the schedules for Shop Orders XX-SO4, XX-SO5, XX-SO6, and XX-SO7. The shop orders are scheduled in the sequence in which they were entered.
  4. On the Gantt chart, double-click Shop Order XX-SO4. The status window for the shop order appears. The need date, start date, and finish date of the shop order appear in this window.
  5. Click Show Contents. The contents window appears. This window displays the quantity due, part number, part description, date entered, earliest possible start date, and adjustment factor for the shop order.
  6. Alternative to step 4 and 5, you can select the shop order in the Gantt Overview pane and again in the Gantt Detail pane to see the details in the Detail Property Pane.
  7. In the Gantt Overview pane, click Plot Settings and then click This Gantt Chart.
  8. Again, click Plot Settings and then click Plot Settings in the menu that appears. The Settings window appears.
  9. In the Settings/Plot Settings/Extended Information tab, click Shop Order in the Class Name list and then select the Need Date check box in the Plot Settings list.
  10. Click Close. The need date of each shop order now appears on the Gantt chart.
  11. In the Tree View/Activities window, right-click the Shop Orders object.
  12. Click Unschedule. The Change Schedule dialog box appears.
  13. Under Operation Resource Assignments, click Maintain Resource Assignment, and then click OK.
  14. Right-click the Shop Orders object again. This time click Sort By EDD. This option sorts the shop orders by earliest due date.
  15. Right-click the Shop Orders object once more. Click Scheduling. The Change Schedule dialog box appears.
  16. Under Operation Schedule Mode, click As Soon as Possible. Under Resource Assignments, click Maintain Resource Assignment. Click OK. The sequence of Shop Orders XX-SO4, XX-SO5, XX-SO6, and XX-SO7 is changed. These shop orders are now scheduled in the following sequence: XX-SO6, XX-SO4, XX-SO5, and XX-SO7.

Sorting by Latest Possible Start Date

Purpose: The purpose of this exercise is to demonstrate how sorting by latest possible start time changes the sequence of the schedule.

Windows:
Simulation Client

  1. In the Tree View/Activities window, right-click the Shop Orders object.
  2. Click Unschedule. The Change Schedule dialog box appears.
  3. Under Operation Resource Assignments, click Maintain Resource Assignment, and then click OK.
  4. Right-click the Shop Orders object again. Click Sort By LPST. This option sorts the shop orders by latest possible start time.
  5. From any shop order, right-click and then click Ext Info Setting. The Extended Information Setting Dialog box appears.
  6. Click Show Ext Plot Setting.
  7. Clear the Need Date check box.
  8. Select the LPST check box.
  9. Click Close.
  10. Right-click the Shop Orders object again.
  11. Right-click the Shop Orders object once more. Click Scheduling. The Change Schedule dialog box appears.
  12. Under Operation Schedule Mode, click As Soon as Possible. Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK. The sequence of Shop Orders XX-SO4, XX-SO5, XX-SO6, and XX-SO7 is changed. These shop orders are now scheduled in the following sequence: XX-SO5, XX-SO6, XX-SO4, and XX-SO7.

Sorting by First Come First Served

Purpose: The purpose of this exercise is to demonstrate how sorting by first come, first served changes the sequence of the schedule.

Windows:
Simulation Client

  1. In the Tree View/Activities window, right-click the Shop Orders object and then click Unschedule. The Change Schedule dialog box opens.
  2. Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK.
  3. Right-click the Shop Orders object and then click Sort by FCFS. This option sorts the shop orders by first come, first served.
  4. From any shop order, right-click and then click Ext Info Setting. The Extended Information Setting Dialog box appears.
  5. Click Show Ext Plot Setting.
  6. Clear the LPST check box, and select the Date Entered check box. Click Close.
  7. Right-click the Shop Orders object once more. Click Scheduling. The Change Schedule dialog box appears.
  8. Under Operation Schedule Mode, click As Soon as Possible. Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK. The sequence of the Shop Orders XX-SO4, XX-SO5, XX-SO6 and XX-SO7 changes. These shop orders are now scheduled in the following sequence: XX-SO4, XX-SO5, XX-SO6, and XX-SO7.

Increasing Shop Order Priority

Purpose: The purpose of this exercise is to show how increasing the priority of a shop order causes it to be scheduled earlier.

Windows:
Shop Order
Simulation Client

Note: The way to increase or decrease the priority of a shop order is to assign it a priority category. This category has an adjustment factor ranging from 1 to 1,000. Each shop order can have a different priority category. You can create a shop order priority category for your site in the Shop Order Basic Data  window. Any shop order that has no priority category gets a default adjustment factor of 100. CBS uses the adjustment factor of a shop order and the priority adjustment factor weight (defined in the Scheduling Basic Data window) to adjust how the shop order is scheduled...

Prerequisites: Make sure there are two priority categories for your site. One priority category should be called High and have an adjustment factor of 1,000. The other priority category should be called Low and have an adjustment factor of 10.

  1. Open the Shop Order window, and query for Shop Order XX-SO7.
  2. In the Priority Category field, enter High.
  3. Open or refresh the Simulation Client.
  4. Find Shop Order XX-SO7. Right-click and then click Show. A dialog box appears showing the status of the shop order.
  5. Click Show Contents. Note the adjustment factor, adjusted need date, adjusted date entered, and adjusted latest possible start time (LPST) of the shop order.

Note: The following calculation is used to determine the adjustment to the need date:

[(New Adjustment Factor – Old Adjustment Factor)/100] * Priority Adjustment Factor Weight

or

[(1000 – 100)/100] * 1 = 9 days (earlier)

The adjusted need date is used when sort by earliest due date is selected. With an adjustment factor of 100, the adjusted need date equals the shop order's need date.

The adjusted latest start time is used when sort by latest possible start time is selected. This value is always calculated from the adjusted need date.

The adjusted date entered is used when sort by first come, first served is selected. With an adjustment factor of 100, the adjusted date entered equals the date entered for the shop order. It is adjusted by the same amount of time as the adjusted need date when an adjustment factor other than 100 is used.

  1. From any shop order, right-click and then click Ext Info Setting. The Extended Information Setting Dialog box appears.
  2. Click Show Ext Plot Setting. Clear the Date Entered check box, and select the Adjusted Need Date check box. Click Close.
  3. In the Tree View/Activities window, right-click the Shop Orders object. Click Unschedule and then Maintain Resource Assignment. Click OK.
  4. Right-click the Shop Orders object again. Click Sort By EDD. This option sorts the shop orders by earliest due date.
  5. Right-click the Shop Orders object once more. Click Scheduling. The Change Schedule dialog box appears.
  6. Under Operation Schedule Mode, click As Soon as Possible. Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK. The sequence of Shop Orders XX-SO4, XX-SO5, XX-SO6, and XX-SO7 changes. These shop orders are now scheduled in the following sequence: XX-SO7, XX-SO6, XX-SO4, and XX-SO5.

Decreasing Shop Order Priority

Purpose: The purpose of this exercise is to show how decreasing the priority of a shop order causes it to be scheduled later.

Windows:
Scheduling Basic Data
Shop Order
Simulation Client

  1. Open the Scheduling Basic Data window, and query for your site...
  2. In the Priority Adjustment Factor Weight field, enter 2.
  3. Open the Shop Order window, and query for Shop Order XX-SO6.
  4. In the Priority Category field, enter or select Low.
  5. Open or refresh the Simulation Client.
  6. On the Settings menu, click Schedule Settings. Note that the value in the Adjustment Factor Weight field is 2, just as your entered in the Scheduling Basic Data window. You can also see the values for earliest possible start time offset, schedule horizon, sequencing horizon, and setup optimization in this window...
  7. In the Tree View/Activities  window, right-click Shop Order XX-SO6 and then click Show. A dialog box appears showing the status of the shop order.
  8. Click Show Contents. Note the adjustment factor, adjusted need date, adjusted date entered, and adjusted latest possible start time (LPST) of the shop order.

Note: The formula for calculating the adjustment used to determine the adjusted need date is as follows:
[(New Adjustment Factor – Old Adjustment Factor)/100] * Priority Adjustment Factor Weight
or
[(10-100)/100] * 2 = -1.8 days (later)
The adjusted need date is set later than the actual need date of the shop order.
The adjusted date entered is set later than the actual date entered of the shop order.

  1. In the Tree View/Activities window, right-click the Shop Orders object and click Unschedule. The Change Schedule dialog box appears.
  2. Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK.
  3. Right-click the Shop Orders object and then click Sort by EDD. This option sorts the shop orders by earliest due date.
  4. Right-click the Shop Orders object once more. Click Scheduling. The Change Schedule dialog box appears.
  5. Under Operation Schedule Mode, click As Soon as Possible. Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK. The sequence of Shop Orders XX-SO4, XX-SO5, XX-SO6, and XX-SO7 is changed. These shop orders are now scheduled in the following sequence: XX-SO7, XX-SO4, XX-SO6, and XX-SO5.

Scheduling Operations

Purpose: The purpose of this exercise is to help you understand the option for full-site rescheduling.

Windows:
Schedule Operations
Simulation Client

Note: Before beginning this exercise, you will need to adjust the material availability of some of the finite materials. You may want to change the purchase lead time, increase or decrease inventory, add or remove non-shop order demands, etc.

  1. Open the Schedule Operations window.
  2. In the Site field, enter or select your CBS site.
  3. Select the dispatch priority rule for the new schedule.
  4. Select any of the other schedule options, as listed in the table below.
Option Description
Set Scheduling Start Time Specifies the number of hours from the current time before an operation may be scheduled.
Re-Assign Resources Reassigns operations to different resources within a work center, tool ID, or labor class.
Include Released Orders Allows shop orders with the Released status to be included in rescheduling.
As Late as Possible Schedules all orders as close as possible to their need dates.
Compress Downstream From Bottleneck Schedules all operations downstream from the bottleneck as soon as possible. This option is applicable only when you are using As Late as Possible.
Refresh Material Updates CBS with the current material availability of all finite materials.
  1. Reopen or refresh the Simulation Client to view the new schedule.
  2. Verify that the shop orders that require the finite materials with the updated availability are scheduled correctly.

Using the Shop Order Scheduling Analysis

Purpose: The purpose of this exercise is to help you understand the information displayed in the Shop Order Scheduling Analysis.

Windows:
Shop Order Scheduling Analysis

  1. Query for your site.
  2. Click the tabs and review the information displayed in them. The table below describes the purpose of each tab.
Tab Purpose
Statistics Displays the overall performance measures of the site's schedule. This tab indicates the number of tardy, early/on-time, unscheduled, and past due orders; maximum tardiness and earliness; and average tardiness and earliness.
Tardy Orders Displays all shop orders that are scheduled to complete after their need dates.
Past Due Orders Displays all shop orders that have operations that are behind schedule.
Unscheduled Orders Displays all shop orders that have one or more unscheduled operations.
Early/On Time Orders Displays all shop orders that are scheduled to complete before their need dates.
Schedule Performance Displays a pie chart that shows the percentage of early/on-time, tardy, and unscheduled orders for the site.
Order Deviation Displays a bar chart that shows the distribution for the number of early/on-time and tardy orders with the deviation from their need dates.
  1. Click the Tardy Orders tab. For each tardy order, the scheduled start date, finish date, and amount of tardiness are shown. In addition, there is a column that lists the capacity-constrained work center.
  2. Highlight a tardy shop order. Use the right mouse button to review the Work Center Load Graph for the capacity-constrained work center.

Note: The work center may not always be the capacity constraint, especially when an operation requires labor or tool resources.