Workload control, to plan against constraints

If workload control (WLC) is used for the master planning of an item, material constraints and/or capacity constraints are taken into account.

Material constraints

Planning against material constraints means that the production plan of a plan item is constrained by the availability of critical components.

Example

If you produce a table with four legs, and 1003 legs are available in week 27, you can produce no more than 250 tables in that week.

A component is only considered as a planning constraint if the following conditions apply:

  • The component is included in the bill of critical materials (BCM) of the end item.
  • The component is defined as a constraint in master planning (see the Constraint check box in the Items - Planning (cprpd1100m000) session).
Capacity constraints

Planning against capacity constraints means that the production plan of a plan item is constrained by the availability of critical resource capacity.

Example

If the final stage of the production process of a chair takes 2 hours at a certain resource, and 101 hours of capacity are available in week 29 for that resource, you can produce no more than 50 chairs in that week.

Capacity at a specific resource is only considered as a planning constraint if the following conditions apply:

  • The resource is included in the bill of critical capacities (BCC) of the item.
  • The resource is defined as a constraint in master planning (see the Constraint check box in the Resource (cprpd2100m000) session).
Planning options

For a planning run using workload control, you have the following options:

  • Do not consider any constraints at all. This is equivalent to using infinite planning.
  • Only consider material constraints.
  • Only consider capacity constraints.
  • Consider material as well as capacity constraints.

You can make your choice by selecting or clearing the appropriate check boxes in the Generate Master Planning (cprmp1202m000) session or the Generate Master Planning (Item) (cprmp1203m000) session.

Planning and replanning

As a rule, the order in which plan items are planned depends on the phase number of the plan unit that each item belongs to. (If a plan item is not linked to a plan unit, the phase number of the item itself is used. For more information, see Planning sequence and phase numbers.

The normal planning order starts with the lowest phase number, and ends with the highest phase number. LN assigns phase numbers in such a way that a manufactured item is planned before its components are planned. In this way, dependent demand originating from the end item is taken into account when its components are planned.

However, this poses a problem if material constraints are to be considered. When the supply of the end item is planned, and the availability of a critical component has to be checked, the projected inventory of this component has not yet been updated.

There are two solutions to this problem:

  • Use the previously computed projected inventory stored in the component's item master plan.
  • Use one or more iterations.

The first solution assumes that the item master plan is updated on a regular basis, so that usually the existing projected inventory values are approximately correct. For an example, see Planning without iterations, an example.

Note

You can update an item master plan's inventory data by choosing the Generate command in the Item Master Plan (cprmp2101m000) session. You can update the inventory data for a range of items in the Initialize, Roll, and Update Scenario (cprpd4200m000) session.

The second solution involves the use of iterations. When the projected inventory computed for a component item drops below the inventory plan, the consequences of this constraint are determined by replanning all items for which this is relevant. For a more detailed description, see Planning with iterations; for an example, see Planning with iterations, an example.

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