Scheduling methods

Work center type-1 is the base capacity level in M3 BE. When using SWB, the capacity is defined on a more detailed resource level, for example, work center type-6. If work center type-1 is defined with number of machines or manpower equals 1, the resource type-6 is defined in a 1:1 relation. If work center type-1 is defined with number of machines or manpower greater than one, there are several methods for how to define resource type-6. This topic describes different methods and how they affect the scheduling in SWB.

These are the Scheduling Methods in SWB:

  1. Individual resource (Standard method)
  2. Aggregated resource
  3. Tool resources
  4. Personnel resource
  5. Fill-up on day bucket level
  6. Secondary operations
  7. Tool and personnel resource as secondary operations

Base example is one work center type-1 which contains 3 resources.

swb_scheduling method

These are the Work center type-6 resources for the methods that are defined above:

  • Method 1 contains 3 resources M1-A, M1-B, and M1-C
  • Method 2 contains resource M2-A
  • Method 3 contains resource M3-A
  • Method 4 contains resource M4-A
  • Method 5 contains resource M5-A
  • Method 7 contains two scenarios:
    1. Three machine resources M6-A, M6-B, and M6-C and tool resource M6-T
    2. Three machine resources M7-A, M7-B, and M7-C and personnel resource M7-P

Individual resource

Resources are defined on individual resource level with NOR=1.

swb_Individual resource_1

Work center W1 contains the three resources. The links from type-1 to type-6 are defined in PDS011.

swb_Individual resource_2

The three operations below are planned. One on each of the three resources in the work center.

swb_Individual resource_3

The next operation is planned on work center with three resources. The resource that results in the earliest end is selected in the simulation. For example, the next operation is planned on resource M1-C.

swb_Individual resource_4

Scheduling is planned one operation at a time on the individual resources.

swb_Individual resource_5

Pros:

  • Scheduling on individual resource level and reporting on individual resource level.
  • Option to have different efficiency, opening hours, and capabilities on the individual resources.
  • Sequencing on resource level is possible.

Cons:

  • Requires resource definition and maintenance on individual resource level.

Aggregated resource

Aggregated resource makes capacity definition and maintenance easier but it also affects the schedule.

swb_Aggregated resource_1

Work center W2 contains one resources M2-A defined on aggregated resource level with NOR=3.

The schedule is still being planned on the individual resource. In this setup, there is only one resource M2-A and the capacity is respected.

swb_Aggregated resource_2

The Scheduling Board has eight orders planned on work center W1 and eight similar orders planned on work center W2. The loading is similar on W1 and W2 but the duration of each operation is three times as short on M2-A, when the capacity is three times as big on M2-A.

When planned on individual resource level an operation with 1:15 takes 1:15 (from 07:00 to 08:15).

swb_Aggregated resource_3

When planned on aggregated resource level the similar operation now has 0:25 duration (from 07:00 to 07:25) equal to 75 minutes divided by 3.

swb_Aggregated resource_4

Pros:

  • You can do resource definition or maintenance on aggregated resource level
  • Capacity is respected

Cons:

  • Duration of operations are reduced
  • Reports on aggregated resource level

Tool resource

Tool resource is designed for tools, where detailed display of plan is not required. The number of tools limits how many operations are scheduled at the same time.

swb_Tool resource_1

Work center W3 contains one resource M3-A defined on aggregated resource level with NOR=3.

swb_Tool resource_2

The Scheduling Board has W3 that emulates an aggregation of three tools. The Scheduling Board and other reports display the operations on tool resources on top of each other. The red lines below operations in the Scheduling Board above indicates two or more operations that are planned in parallel.

You can view plan details using the Tool analyzer icon from the operations planned on tool resources.

swb_Tool resource_3

The marked operation starts at 07:30 and ends at 08:30. The overlapping operations are displayed in blue and earlier or later operations in light brown.

Pros:

  • Resource definition/maintenance can be done on aggregated resource level
  • Capacity is respected
  • Duration of operations emulates scheduling one resource

Cons:

  • Tool resource affects simulation performance
  • Reports on aggregated resource level.
  • Average efficiency, opening hours, and capabilities for all resources
  • No sequencing
  • Learning curve is not handled

Personnel resource (for SWB 16.1.0)

Personnel resource is designed for personnel, where you can start an operation and partly produce then restart later when there is a free capacity.

swb_Personnel resource_1

Work center W4 contains one resource M4-A defined on aggregated resource level with NOR=3.

swb_Personnel resource_2

The Scheduling Board is identical for Personnel resource and Tool Resource because there is no capacity gap. These are the differences between Tool Resource and Personnel Resource:

  • Personnel can start or stop multiple times and use any available capacity even if free capacity is divided into several periods.
  • Tool must only have one start or stop and are planned like Lego blocks. You might have small capacity gaps which you cannot utilize.

This is an example of the difference between Personnel resource and Tool resource. Three operations are already scheduled. Notice the first operation starts at 08:04 and leaves a small capacity gap from 08:00 to 08:04.

swb_Personnel resource_3

The personnel resource schedules the next operation from 08:00 to 08:04 and from 08:19 to 08:37.

swb_Personnel resource_4

The tool resource schedules the next operation from 08:19 to 08:41 (one start or stop).

swb_Personnel resource_5

Pros:

  • Same as Tool resources

Cons:

  • Same as Tool resources but performance is affected even more by flexibility to use any capacity gap
  • Learning curve is not handled

Fill-up on day bucket level

Fill-up resource is designed for assembly groups, where capacity is considered on day bucket level. Assembly groups often contains several persons and many operations are handled at the same time. You must handle a mix of small operations and large operations for the fill-up resource. If operations require a lot of operation time and takes many days or weeks to complete, there is a limit to how many persons can work on the same order at the same time.

The operations are scheduled by using the capacity on day bucket level, for example, the capacity is filled-up. If there is a free capacity in a day bucket, you can plan the operation there. The operation on fill-up resources can use capacity from one or multiple day buckets and use all available capacity gaps. The capacity on day bucket level ensures that capacity is used even if there is remaining capacity which is less than required by one operation.

swb_Fill-up on day bucket level_1

Work center W5 contains one resources M5-A.

Fill-up resources are designed for day bucket capacity and you must have a fill-up example on day level.

The fill-up resources in the example contains five persons working 8 hours (from 07:00 to 15:00) which gives a daily capacity of 40 hours. A maximum of two persons are available per operation.

swb_Fill-up on day bucket level_2

The first operation in red requires 20 hours of capacity and earliest start of operation is 12:00 on day 1. On day 1, two persons can produce 6 hours from 12:00 to 15:00. The operation uses 6 hours of capacity on day 1 and 34 hours remain on the capacity on day 1. The operation uses 14 hours of capacity on day 2 (from 07:00 to 14:00) and 26 hours remain on the capacity on day 2. The red operation starts 12:00 on day 1 and ends at 14:00 on day 2.

swb_Fill-up on day bucket level_3

The second operation in blue requires 38 hours of capacity and earliest start of operation is 00:00 on day 1. The operation uses 16 hours of capacity on day 1, 16 hours of capacity on day 2, and 6 hours of capacity on day 3. The blue operation starts at 07:00 on day 1 and ends at 10:00 on day 3.

swb_Fill-up on day bucket level_4

The third operation in green requires 24 hours of capacity and earliest start of operation is 11:00 on day 1. The operation uses 8 hours of capacity on day 1 from 11:00 to 15:00. The operation uses 10 hours of capacity on day 2 because 10 hours only remain after the blue operation was planned. The operation uses 6 hours of capacity on day 3. The green operation starts at 11:00 on day 1 and ends at 10:00 on day 3.

swb_Fill-up on day bucket level_5

The fourth operation in orange requires 16 hours of capacity and earliest start of operation is 12:00 on day 1. The operation uses 6 hours of capacity on day 1 from 12:00 to 15:00. The operation uses no capacity on day 2 because there is no capacity left after the green operation was planned. The operation uses 10 hours of capacity on day 3. The green operation starts at 12:00 on day 1 and ends at 12:00 on day 3.

The capacity is respected on day bucket level. Loading inside the day is not evenly distributed. If more detailed planning is needed, you can instead define one fill-up as several normal resources.

Pros:

  • Flexible resource definition for an assemble group handling multiple order at the same time.
  • You must plan a non-critical part of the factory. Scheduling on fill-up resource creates a good enough plan. You can then use the focus of the planner for the bottleneck and critical part of the factory.

Cons:

  • Ensure that capacity on day level is sufficient detailed scheduling
  • In some situations, simulation performance is affected if there are small capacity gaps, which can start an operation then several days until remaining free capacity to finish the operation.

Secondary operations

If several resources are required for execution of an operation, SWB can plan on both primary and secondary operation at the same time.

These are some examples:

  • Resource and tool
  • Resource and setup person
  • Line production where you must have several resource available at the same time

Primary and secondary operations are standard defined with normal resources. On the secondary operation, the parallel operation overlap codes define how the secondary operation is planned related to the primary operation.

The primary operation is planned first then the secondary operations are planned consequently. In case there is no valid plan for the secondary operations, the primary operation is planned later until both primary and secondary operations are planned correctly. There is a limit to how far into the future SWB is searching for gaps for secondary operations. Select Automatic simulation > Advanced > Horizon to search the gaps for the secondary operations. If there is no valid place for all operations, the first gap for the primary operation is used and an error message is displayed on the invalid secondary operations.

Tool and personnel resources as secondary operations

In the third and fourth sections, tool resource and personnel resource are described as a primary operation. You can also have tool resource and personnel resource as a secondary operation. The difference between the, has a large consequence.

For example, there are three primary machines W6-A, W6-B, and W6-C. There is also a tool resource W6T with two tools.

swb_Tool and personnel resources as secondary operations_1

The first operation is planned from 07:00 to 08:18. The second operation is planned from 07:03 to 07:57 that leaves a small capacity gap from 07:00 to 07:03.

swb_Tool and personnel resources as secondary operations_2

You must have a continuous capacity for the tool resource and you cannot use the capacity gap. Therefore, the third operation is planned from 07:57 to 09:03.

swb_Tool and personnel resources as secondary operations_3

For personnel resource, the first and second operation are planned identically.

swb_Tool and personnel resources as secondary operations_4

You can use the third operation capacity gap from 07:00 to 07:03 on machine W7-C. The personnel is working on W7-B between 07:03 to 07:57 and come back to finish W7-C in interval from 07:57 to 09:00.

If you compare tool resource and personnel resource, you can use the personnel resource capacity gap and finish the W7-C at 09:00 compared to 09:03 with tool resource. At the same time, the machine W7-C is busy from 07:00 to 09:00 and W6-C is only busy from 07:57 to 09:03.

If you drill down on the tool resource, the continuous plan from 08:04 to 08:34 is displayed.

swb_Tool and personnel resources as secondary operations_5

If you drill down on the personnel resource, the two periods from 07:00 to 07:04 and 08:04 to 08:30 is displayed.

swb_Tool and personnel resources as secondary operations_6
Note: The loading principles are defined on work center resource in PDS010/K

These are the loading principles:

  • 0 - Normal
  • 1 - Oven
  • 2 - Fill-up
  • 3 - Quantity (fill up)

The maximum restriction overrules loading principles if these values below are used:

  • TOOL = Tool resource
  • PERS = Personnel resource

Secondary operation overlap code

The operation for tool resource has operation time and overlap code B, where start or end is inherited from the primary operation to tool operation.

swb_Secondary operation overlap code_1

The operation for personnel resource has full operation time and overlap code K. If the primary operation is planned, the Personnel operation is also planned. If the Personnel operation is longer than the primary operation, the primary operation is prolonged to the same length as the personnel operation if possible.

swb_Secondary operation overlap code_2

These are the limitations of the Personnel overlap:

  • You must have a normal resource for the primary operation. Fill-up, oven, tool, and personnel resource are not allowed.
  • You can only handle a single Personnel overlap operation for each primary operation.
  • Maximum duration is not handled but you can use the maximum duration on the primary operation.
  • Learning curve is not handled.
  • Overlap base is not used.