Workload control, a detailed example

Six plan items are produced in the same work center. If the workload exceeds the capacity constraints, it is divided over the plan periods by means of a backward planning pass.

The parameter setting in the Work Load Control Performance Indicators (cpwlc2520m000) session determines which item's production volume is the first to be allocated to a particular plan period and which production volume must be moved to an earlier period.

This topic contains examples of the following parameter settings:

  • Example 1 : Plan item priority

    The production of the plan item with the highest priority is allocated first. If a plan period's production capacity is exceeded, production volumes are moved to the preceding period. For details, refer to Example 1 : Plan item priority.

  • Example 2 : Volume x times cost

    The plan item of which the highest value of production volume has been shifted in the previous planning step is allocated first. If a plan period's production capacity is exceeded, production volumes are moved to the preceding period. For details, refer to Example 2 : Volume moved x cost.

Example 1 : Plan item priority

The production of the plan item with the highest priority is allocated first. If a plan period's production capacity is exceeded, other plan items' production volumes are moved.

Settings

The following parameter settings are used:

Backward Plan. Rule = Volume Moved
Consider Material Costs = No
Consider Production Costs = No
Consider Item Priority = Only
Note: The backward planning rule Volume Moved is overruled by the setting of the Consider Item Priority parameter.

Relevant item data:

Item Priority
A Very Low
B Medium
C High
D Low
E Medium
F Medium

The plan items are always planned in the following order: C - (B, E, or F) - D - A.

You can specify a plan item's priority in the Items - Planning (cprpd1100m000) session, in the Priority field.

Ideal plan

In the first planning step, the capacity constraints are ignored. This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 70 30 -
C - - 50 -
D - - 10 110
E - - - 15
F - - - 35
Total 70 70 90 160

The available capacity allows for a total production volume of 100 in each plan period.

To adjust the plan in period 4

The capacity in period 4 is exceeded by 60.

In period 4, only the plan items D, E, and F have a production volume. These plan items are planned in the order: (E or F) - D.

This means:

  • First, the production volume of items E and F are planned in period 4. That leaves a production capacity open for a production volume of 50 (= 100 -15 -35).
  • Now, the production volume of item D is planned, but only a volume of 50 can be planned in period 4. The remaining 60 are moved backward to period 3.
  • In period 3, a volume of 10 was already planned for item D. Together with the moved volume coming from period 4, this makes 70.

This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 70 30 -
C - - 50 -
D - - 70 50
E - - - 15
F - - - 35
Total 70 70 150 100

To adjust the plan in period 3

The capacity in period 3 is exceeded by 50.

The plan items B, C, and D have a production volume in period 3. These plan items are planned in the order: C-B-D.

This means:

  • First, the production volume of item C is planned in period 3. That leaves a production capacity open for a production volume of 50 (= 100 -50).
  • Then, the production volume of item B is planned, which leaves a production capacity open for a production volume of 20 (= 100 -50 -30).
  • Next, the production volume of item D is planned, but only a volume of 20 can be planned in period 3. The remaining 50 are moved backward to period 2.

This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 70 30 -
C - - 50 -
D - 50 20 50
E - - - 15
F - - - 35
Total 70 120 100 100

To adjust the plan in period 2

The capacity in period 2 is exceeded by 20.

The plan items B and D have a production volume in period 2. These plan items are planned in the order: B-D.

Part of the production volume of item D is moved to period 1.

This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 70 30 -
C - - 50 -
D 20 30 20 50
E - - - 15
F - - - 35
Total 90 100 100 100

Example 2 : Volume moved x cost

The plan item of which the highest value of production volume has been shifted in the previous planning step is allocated first. If a plan period's production capacity is exceeded, other plan items' production volumes are moved. Value of production volume is defined as (unit cost x moved production volume).

Settings

The following parameter settings are used:

Backward Plan. Rule = Volume Moved
Consider Material Costs = Yes
Consider Production Costs = No
Consider Item Priority = No

Ideal plan

In the first planning step, the capacity constraints are ignored. This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 70 30 -
C - - 50 -
D - - 10 110
E - - - 15
F - - - 35
Total 70 70 90 160

The available capacity allows for a total production volume of 100 in each plan period.

To adjust the plan in period 4

The capacity in period 4 is exceeded by 60.

Relevant item data for plan period 4:

Item A B C D E F
Volume Moved 0 0 0 0 0 0
Material Costs ($) 60 30 80 4 10 1
Volume Moved x Costs 0 0 0 0 0 0
Production Volume of Period 4 0 0 0 110 15 35

At the start of the backward planning step, the Volume Moved equals zero for all plan items. In that case LN uses the production volume to determine which items will be planned first.

The plan items are planned in the order: D-F-E. This means:

  • First, the production volume of item D is planned in period 4.
  • A volume of 100 can be planned in period 4; the remainder is moved backward to period 3.
  • The production volumes of the items E and F are also moved to period 3.

This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 70 30 -
C - - 50 -
D - - 20 100
E - - 15 -
F - - 35 -
Total 70 70 150 100

To adjust the plan in period 3

The capacity in period 3 is exceeded by 50.

Relevant item data for period 3:

Item A B C D E F
Volume Moved 0 0 0 10 15 35
Material Costs ($) 60 30 80 4 10 1
Volume Moved x Costs 0 0 0 40 150 35
Production Volume of Period 3 0 30 50 20 15 35

The plan items that have already been moved are planned in the order of (volume moved x costs): E-D-F. The other plan items are planned in the order of production volume: C-B-A.

This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 30 100 - -
C - 20 30 -
D - - 20 100
E - - 15 -
F - - 35 -
Total 70 120 100 100

To adjust the plan in period 2

The capacity in period 2 is exceeded by 20.

Relevant item data for period 2:

Item A B C D E F
Volume Moved 0 30 20 0 0 0
Material Costs ($) 60 30 80 4 10 1
Volume Moved x Costs 0 900 1600 0 0 0
Production Volume of Period 2 0 100 20 0 0 0

The plan items that have already been moved are planned in the order of (volume moved x costs) : C-B.

Part of the production volume of item B is moved to period 1.

This results in the following plan:

Item Period 1 Period 2 Period 3 Period 4
A 40 - - -
B 50 80 - -
C - 20 40 -
D - - 20 100
E - - 15 -
F - - 35 -
Total 90 100 100 100
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