The Scheduling Data Model

The scheduling data model encapsulates all the knowledge and experience gained over the years by Outperform Planning. This section describes it from a functional perspective:

Batch, Activity, Process, and Process Steps

A batch is a series of one or more activities. Activities occupy resources and can put a claim on enabling resources. A batch is made up of a process; activities represent the steps in that process.

The Link to Resources

Process steps link to resource groups and every resource can be in one or more resource groups. In this way, the system knows which resource can be selected for an activity. The details on rates and efficiencies are shared with the planning engines and held in the so-called resource BOM factors.

Downtime Activities

A downtime activity is a period when the resource is allocated but not generating any output. This aspect is the same for a changeover segment of an activity, but a changeover is related to product and product sequence, whereas downtime only represents the claim on a resource. Downtimes can be either flexible (like a flexible cleaning of a resource) or fixed (like a lunch break). For fixed downtimes, the algorithm is not allowed to move them, so it treats them as obstacles.

Changeovers

A changeover is the time spent before and/or after an activity to prepare for the following activity. Similar to a downtime activity, the resource is allocated but does not generate any output. During this time, the machine configuration is usually changed to align with the requirements of the following production and the machine is cleaned from leftovers of the preceding production batch.

Changeovers are not limited to scheduling. Like batches, they need to be considered already in planning to ensure that it is possible to schedule all planned production and their changeovers. However, planning often does not consider changeovers in fine detail. Instead, planning typically considers a general provision for time lost to changeovers, created from an average of historical changeover values.

Changeovers are defined by characteristics on product level, like product type and pack-size. The combination of products that can be produced on a production line will create a changeover matrix for the applicable characteristic for that production line. The matrix will then specify the duration involved when a product characteristic changes from one value to another.

A configuration will specify whether the changeover durations are additive, or the maximum of all applicable durations will apply. In the latter option, the system assumes that the factory crew can do all the necessary tasks in parallel, and the longest duration is then the duration that defines the changeover.