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.
- 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 |
- Reopen or refresh the Simulation Client.
- Load the All Shop Orders scheduling scenario. All shop orders are plotted in the object
table area of the Gantt Overview pane.
- 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.
- 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.
- 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.
- 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.
- In the Gantt Overview pane, click Plot Settings and
then click This Gantt Chart.
- Again, click Plot Settings and then click Plot Settings in
the menu that appears. The Settings window appears.
- 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.
- Click Close. The need date of each shop order now appears on the
Gantt chart.
- In the Tree View/Activities window, right-click the Shop Orders object.
- Click Unschedule. The Change Schedule dialog box
appears.
- Under Operation Resource Assignments, click Maintain Resource Assignment,
and then click OK.
- Right-click the Shop Orders object again. This time click Sort By EDD. This option sorts the shop orders by
earliest due date.
- Right-click the Shop Orders object once more. Click Scheduling.
The Change Schedule dialog box appears.
- 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
- In the Tree View/Activities window, right-click the Shop Orders object.
- Click Unschedule. The Change Schedule dialog box
appears.
- Under Operation Resource Assignments, click Maintain Resource Assignment,
and then click OK.
- Right-click the Shop Orders object again. Click Sort By LPST.
This option sorts the shop orders by latest possible start time.
- From any shop order, right-click and then click Ext Info Setting.
The Extended Information Setting Dialog box appears.
- Click Show Ext Plot Setting.
- Clear the Need Date check box.
- Select the LPST check box.
- Click Close.
- Right-click the Shop Orders object again.
- Right-click the Shop Orders object once more. Click Scheduling.
The Change Schedule dialog box appears.
- 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
- In the Tree View/Activities window, right-click the Shop Orders
object and then click Unschedule. The Change Schedule
dialog box opens.
- Under Operation Resource Assignments, click Maintain Resource Assignment. Click OK.
- Right-click the Shop Orders object and then click Sort
by FCFS. This option sorts the shop orders by first come, first served.
- From any shop order, right-click and then click
Ext Info Setting. The Extended Information Setting Dialog
box appears.
- Click Show Ext Plot Setting.
- Clear the LPST check box, and select the Date Entered check box.
Click Close.
- Right-click the Shop Orders object once more. Click Scheduling.
The Change Schedule dialog box appears.
- 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.
- Open the
Shop Order window, and query for Shop Order XX-SO7.
- In the Priority Category field, enter High.
- Open or refresh the Simulation Client.
- Find Shop Order XX-SO7. Right-click and then click Show. A dialog
box appears showing the status of the shop order.
- 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.
- From any shop order, right-click and then click Ext Info Setting.
The Extended Information Setting Dialog box appears.
- Click Show Ext Plot Setting. Clear the Date Entered
check box, and select the Adjusted Need Date check box. Click Close.
- In the Tree View/Activities window, right-click the Shop Orders object.
Click Unschedule and then Maintain Resource Assignment. Click OK.
- Right-click the Shop Orders object again. Click Sort By EDD.
This option sorts the shop orders by
earliest due date.
- Right-click the Shop Orders object once more. Click Scheduling.
The Change Schedule dialog box appears.
- 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
- Open the
Scheduling Basic Data window, and query for
your site...
- In the Priority Adjustment Factor Weight field, enter 2.
- Open the
Shop Order window, and query for Shop Order XX-SO6.
- In the Priority Category field, enter or select Low.
- Open or refresh the Simulation Client.
- 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...
- 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.
- 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.
- In the Tree View/Activities window, right-click the Shop
Orders object and click Unschedule. The
Change Schedule
dialog box appears.
- Under Operation Resource Assignments, click Maintain Resource
Assignment. Click OK.
- Right-click the Shop Orders object and then click Sort
by EDD. This option sorts the shop orders by
earliest due date.
- Right-click the Shop Orders object once more. Click Scheduling.
The Change Schedule dialog box appears.
- 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.
- Open the
Schedule Operations window.
- In the Site field, enter or select your CBS site.
- Select the dispatch priority rule for the new schedule.
- 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. |
- Reopen or refresh the Simulation Client to view the new
schedule.
- 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
- Query for your site.
- 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. |
- 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.
- 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.