Schedule Work Order with CBS

What is CBS?

IFS/CBS or IFS/Constraint Based Scheduling is an add-on of an in-memory advanced Scheduling Server which allows you to perform finite capacity scheduling in a resource and material constrained environment. It solves the problem of when to complete a given set of jobs that represent work on a set of resources. With regard to work orders CBS will facilitate:

• Instant work order scheduling based on the availability of resources
• Manage the task of scheduling

• Work orders within work order structures
• Work orders connected to projects
• A combination of the above
• Stand alone work orders

For more in-depth information on CBS please refer to the following online help document: Constraint Based Scheduling.

Different Ways of Scheduling Work Orders

There are five possible scenarios for which you can schedule work orders:

• A stand alone work order - A work order that has no connections to a work order structure or project.
• A work order is part of a project and all work orders connected to that project needs to be scheduled.
• A work order is part of a work order structure and all connected work orders need to be scheduled.
• A work order is part of a work order structure and a project, and all the work orders in the structure/project need to be scheduled - applicable for Maintenance Task Networks in IFS/Vehicle Information Management.
• A work order is part of a work order structure or a project and only the specific work order needs to be scheduled - applicable for a new work order that should be included in a work order structure or project that has been released. If required the entire structure/project can be re-planned to include the new work.

Scheduling Work Orders with CBS

In order to schedule a work order using IFS/CBS the work order site must be CBS enabled. CBS sites are created in IFS/Basic Data for Constraint Based Scheduling; the CBS site also contains information about the server and port used by the CBS server. Once the relevant work order is set to Prepared it will be transferred to the CBS server for scheduling. Before setting the work order to Prepared however you need to make sure that all information the CBS server would require to make the scheduling (described below) is present in the work order. The work order can be planned in the CBS server until it reaches the Work Done status, after which it will be removed from the CBS server and therefore can no longer be scheduled.

Note: You cannot use the Resource Allocation feature and CBS at the same time; therefore you need to decide which sites need to be CBS enabled. CBS assumes that it will plan the resources for the entire work order site and will update the relevant resource allocation tables using the Resource Allocation feature.

Data Exchange between the Database and CBS Server

Basic data (Resources) and work order information is read automatically from the database when the CBS server starts and/or reboots. When information is updated in the database for the objects described below they are also updated in the CBS server provided the site to which they are connected is CBS enabled.

The following picture depicts how data is exchanged between the database and the CBS server.

Resources - Includes the basic data related to IFS Maintenance;

• Calendars (of the maintenance organization) - Enables the management of deviations or exceptions on an organizational level. Calendars are used with regard to employees and tools-and-facilities; this however means that the tools-and-facilities will not be available to other organizations outside the working hours of the owning maintenance organization.
• Crafts - That are connected to the CBS enabled site.
• Employees - That are connected to the CBS enabled site.
• Employee & Craft relationship - In order for the CBS server to know which craft a certain employee can assume.
• Teams - That are connected to the CBS enabled site. Information on the team, team leader, employee, maintenance organization and the validity period of the maintenance team will be transferred to the CBS server.
• Team members - That are connected to the team belonging to the CBS enabled site.
• Tools-and-Facilities - Tools-and-facilities are defined per site and per maintenance organization. In terms of prioritization of the applicable tools for a work order operation or subtask the tools owned internally (i.e., by the maintenance organization) are given priority over those owned externally.

Work Order Information - Includes;

• Information related to work order headers - All work orders for the specific site that is in status Prepared, Released or Started will be transferred to the CBS server during start up. The information sent includes; work order number, directive, object, maintenance organization, priority, contractor, work leader, late start date and requested finish date.
• Work order structures and related dependencies. The dependencies between the different work orders in the work order structure are read from the work order dependencies table.
• Project activity dependencies - Project dependencies are read from the project the work orders are connected to and forms predecessor and successor relationships between work orders.
• Work order operations and related dependencies - All operations and subtasks, excepting those that are cancelled or defined as slave duplicates, will be transferred to the CBS server during start up. Information, such as, the maintenance team and operation status will be transferred. If a team is added as a constraint, CBS will only schedule employees that are members of this team.
• Work order material requirements - The material needs to be connected to the operation for which it is required.
• Work order tools-and-facilities requirements - Tools-and-facilities need to be connected to the operation for which it is required.

Scheduled Orders - Includes; Work Order Planned Start and Finish Dates, Work Order Operation Planned Start and Finish Dates, Top Work Order Planned Start and Finish Dates and Resource Allocations.

Scheduling Constraints

During the scheduling process the CBS server may come across resource constraints that can't be resolved and will return an incomplete scheduled order. The scheduling status of the relevant operation line for which a resource constraint can't be resolved (in the work order) will be set to Unscheduled and allocations will not be made. The Scheduling Constraint field on the Prepare Work Order/General or Work Order Execution Logic/General tab will be set to Unresolved or Unresolved (Tardy). The Unresolved (Tardy) value will be set if all resource constraints have been resolved but the requested finish date on the work order has not been met. With regard to work order structures - the Scheduling Constraint of the parent work order will be set to Unresolved or Unresolved (Tardy). Changes Pending is displayed when there are changes made on the work order or its operations that have not yet been rescheduled. Work orders that contain unresolved scheduling constraints cannot be started. To do so you need to first resolve the issues and reschedule the work order.

Buffer Index Calculation

This calculation is performed during the reschedule of a work order/project structure. The buffer index is the comparison between the progress of a shop visit and how much of the project buffer has been consumed. In order to perform the calculation, the following information must exist:

• The structure progress of the work order structure.
• The required end date of the visit - This is specified in the Requested Finish field for the top work order in a work order structure.
• The original planned end date of the visit - This is specified in the Structure Finish at Start field. This is the date calculated by CBS as being the date on the last CBS run before the visit started, i.e., when the top work order in the structure started.
• The current planned end date of the shop visit - This is specified in the Structure Finish field. As CBS continuously recalculates the execution schedule, the current planned end date is moved backward or forward depending on whether things go faster or slower.

The formulas used to perform the calculation are listed below:

Background Scheduling

It is possible to automate the scheduling run of CBS by using the Scheduled Tasks feature. Here you can configure valid scheduling parameters so that the schedule run is performed through a background job daily at a specific time or on certain days of the week/month. You can schedule a run of CBS for:

• A complete schedule site run, where the parameters are equivalent to those used when scheduling a site manually.
• A run of a specific work order structure, where the parameters are equivalent to those used when scheduling a work order structure manually.
• A run of a certain project, where the parameters are equivalent to those used when scheduling a project manually.

When the scheduled task is run, the site, work order structure and/or project is scheduled and up-to-date.