EGN_5623 Detailed Scheduling

7/30/2019 EGN_5623 Detailed Scheduling

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Detailed Scheduling (DS)

EGN 5623 Enterprise Systems Optimization(Professional MSEM)

Fall, 2012


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Detailed Scheduling (DS)

Theories & Concepts


Fall, 2012


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Topics

DS concepts1. Finite and infinite loading

2. Scheduling directions

3. Sequencing rules

4. Criteria for evaluation of sequencing rules

5. Controlling changeover costs

6. Minimize total production time

DS in SAP APO


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Process-Focused Operations

Process-focused factories are often calledjob shops.

A job shops work centers are organizedaround similar types of equipment or

operations. Workers and machines are flexible and

can be assigned to and reassigned tomany different orders.

Job shops are complex to schedule.


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Scheduling and Shop-FloorDecisions (Review)

MaterialRequirementsPlan (MRP)

CapacityRequirementsPlan (CRP)

Order-Processing orRouting Plans

Planned

Order ReleasesReport

Work Center

Loading andOvertime Plan

Assignment of

Orders toWork Centers

MasterProductionSchedule (MPS)

Product DesignandProcess Plans

Day-to-Day Scheduling and Shop-Floor Decisions


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Pre-production Planning

Design the product in customer order Plan the operations the product must pass

through ..... this is the routing plan

Work moves between operations on amove ticket


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Common Shop Floor ControlActivities

The production control departmentcontrols and monitors order progressthrough the shop. Assigns priority to orders

Issues dispatching lists Tracks WIP and keeps systems updated

Controls input-output between work centers

Measures efficiency, utilization, and

productivity of shop


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Shop Floor Planning and Control

Input-Output Control Gantt Chart Finite and Infinite Loading Forward and Backward Scheduling


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Input-Output Control

Input-output control identifies problemssuch as insufficient or excessive capacityor any issues that prevents the order frombeing completed on time.

Input-output control report comparesplanned and actual input, planned andactual output, and planned and actual

WIP in each time period


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Gantt Charts

Gantt charts are useful tools to coordinatejobs through shop; graphical summary ofjob status and loading of operations


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Gantt Charts (Review)

Machining

Fabrication

Assembly

Test

Tue. Wed. Thu. Fri. Sat.Work Centers Mon.

E F G

C D E

H C

F

ED

H C D

Scheduled Progress Setup, Maint.


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Assigning Jobs to Work Centers:How Many Jobs/Day/Work Center

Infinite loading Assigns jobs to work centers without regard tocapacity

Unless excessive capacity exists, long queues

occur Finite loading

Uses work center capacity to schedule orders Popular scheduling approach

Integral part of CRP


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Order-Sequencing Problems

Sequencing Rules Criteria for Evaluating SequencingRules

Comparison of Sequencing Rules Controlling Changeover Costs Minimizing Total Production Time


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Order-Sequencing Rules (Review)

First-Come First-Served (FCFS)Next job to process is the one that arrived firstamong the waiting jobs

Shortest Processing Time (SPT)

Next job to process is the one with the shortestprocessing time among the waiting jobs

Earliest Due Date (EDD)Next job to process is the one with the earliestdue (promised finished) date among the waiting

jobs


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Order-Sequencing Rules (Review)

Least Slack (LS)Next job to process is the one with the least[time to due date minus total remainingprocessing time] among the waiting jobs

Critical Ratio (CR)

Next job to process is the one with the least[time to due date divided by total remainingprocessing time] among the waiting jobs

Least Changeover Cost (LCC)Sequence the waiting jobs such that total

machine changeover cost is minimized


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Evaluating the Effectivenessof Sequencing Rules (Review)

Average flow time - average amount oftime jobs spend in shop

Average number of jobs in system -

Average job lateness - average amount oftime jobs completion date exceeds itspromised delivery date

Changeover cost - total cost of makingmachine changeovers for group of jobs


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Experience Says (Review)

First-come-first-served Performs poorly on most evaluation criteria Does give customers a sense of fair play

Shortest processing time Performs well on most evaluation criteria But have to watch out for long-processing-timeorders getting continuously pushed back

Critical ratio Works well on average job lateness criterion

May focus too much on jobs that cannot becompleted on time, causing others to be latetoo.


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Controlling Changeover Costs(Review)

Changeover costs - costs of changing aprocessing step in a production systemover from one job to another Changing machine settings

Getting job instructions Changing material Changing tools

Usually, jobs should be processed in a

sequence that minimizes changeovercosts


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Controlling Changeover Costs(Review)

Job Sequencing Heuristic First, select the lowest changeover cost amongall changeovers (this establishes the first twojobs in the sequence)

The next job to be selected will have the lowestchangeover cost among the remaining jobsthat follow the previously selected job


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Minimizing Total Production Time

Sequencing n Jobs through Two WorkCenters When several jobs must be sequenced throughtwo work centers, we may want to select a

sequence that must hold for both work centers Johnsons rule can be used to find thesequence that minimizes the total productiontime through both work centers


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DS in SAP APO

Tasks and activities of detailed scheduling Controlling Detailed Scheduling

Dates/Times and Planning Directions

Resource Availability

Selection of Resources

Time Relationships

Pegging Relationships Automatic Propagation of Changes

Determining the Setup Time for Sequence-Dependent Setup Activities

Synchronizing Activities on Multi-resources

Block planning

Scheduling Log

Terminating Scheduling

Detailed Scheduling Heuristics


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Tasks of Detailed SchedulingDetailed scheduling is used to:

1. Determine the resources and dates/times for carrying

out operations, taking resource and product availability

into consideration.

2. Support the scheduler in scheduling resources when

creating an optimal operations sequence.
http://help.sap.com/saphelp_scm50/helpdata/en/12/c78f795743d311b60f0060b03c2bff/content.htmhttp://help.sap.com/saphelp_scm50/helpdata/en/12/c78f795743d311b60f0060b03c2bff/content.htm


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Activities of Detailed SchedulingBasic DS Activities:

Scheduling dispatching operations to resources at a specific

date/time

Rescheduling

dispatching already scheduled operations to adifferent date/time or to different resources

De-allocating

removing scheduled operations from the resource

schedule

Adjusting a new date/time or new resources are assigned to a

de-allocated operation.

Fixing

the resource and date/time for the operation is fixed.


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Activities of DS: Schedule

Schedule:For an operation of a newly created order or for a de-

allocated operation

1. The resources are determined on which the operation

should be processed

2. The date/time is determined when the operation

should be processed on the resources

With scheduling, the operation is dispatched to the

resources. Scheduling an order means scheduling all theoperations of the order.
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Activities of DS: Reschedule

Reschedule:

1. A new date/time or new resources are specified for a

scheduled operation.

2. With rescheduling, the operation remains loaded onresources.

3. After rescheduling, it loads either the previous resources

or the new resources.

4. Rescheduling an order means rescheduling all the

operations of the order.


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Activities of DS: De-allocate Remove an operation from the resource schedule.

With de-allocation, an operation is given the status

de-allocated. The operation no longer loads any

resources.

De-allocating an order means de-allocating all the

operations of the order.

An operation in the SAP APO system is

either scheduled(with no separate status),

or de-allocated (in this case it has the status de-

allocated).


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Activities of DS: Adjust

A new date/time or new resource is assigned to a de-

allocated operation.

In the case of an adjustment, the operation retains the

status de-allocated. The operation does not load the

resources to which it is assigned. Adjusting does notchange any resources schedules.

Adjusting is a detailed scheduling activity that is carried

out automatically by the system for dependent objects

(for example, if relationships or pegging relationships

have to be adhered to). You cannot adjust de-allocated

operations manually.


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Activities of DS: Fix

1. The resource and date/time for the operation is fixed.

2. Through the fixing process, a scheduled or de-allocated

operation is assigned the status fixed.

3. A fixed scheduled operation cannot be rescheduled or

de-allocated, and a fixed de-allocated operation cannot

be scheduled or adjusted.


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Integrated Distribution &Production Planning

SAP Implementation


Fall, 2012


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Prerequisites of DS

The system can trigger detailed scheduling activitiesautomatically. For example, it automatically schedules the

order operations when an order is created.

Three ways to start detailed scheduling activities:

production planning run,

detailed scheduling planning board, or

resource planning table specifically forselected

operations or orders.
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Production Planning Run

The user may execute planning online, or in the backgroundfor selected orders:

1. online planning: for small data quantities (for

example, for test purposes),

2. background planning: for mass planning.


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Detailed Scheduling Planning BoardPurpose:

Graphical representation of the planning situation

Graphically represent different aspects of scheduling in the charts of

the detailed scheduling planning board. For example, you can show

the situation of operations on resources over time and the

development of the resource utilization or pegging relationships

between orders over time.

Interactive solution of planning problemsYou can perform interactive scheduling on the detailed scheduling

planning board to solve scheduling problems such as sequence or

date/time problems on resources. Various scheduling functions andheuristics are available in addition to manual scheduling with

Drag&Drop.
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Detailed Scheduling Planning Board

Integration

The detailed scheduling planning board is integrated indifferent Production Planningapplications.

You can call up the detailed scheduling planning board

directly:

In the area menu for production planning In order processing

In the product planning table

SAP provides the detailed scheduling planning board

with standard settings (for example, for setup or layout).If you want to configure a detailed scheduling planning

board for your specific scheduling requirements, you

must make the appropriate settings.
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Detailed Scheduling Planning Board

Layout of the Detailed Scheduling Planning BoardWhen you invoke the detailed scheduling planning board for

the first time, the selection area is shown in the left-hand

part of the screen. You can control the display of the

selection area via Settings -> User Settings and save the

setting on a user-specific basis.

The setting you make on the detailed scheduling planning

board is independent of the setting in the resource planning

table (see Configuring the Resource Planning Table).The selection area serves to provide an overview of the

loaded products and resources and to show and hide

objects (see Hiding and Showing Objects).
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SAP APO Planning Board (Interface)

SAP APO Production Planning Interactive Production Planning DetailedScheduling Detailed Scheduling Planning Board/Variable view

(APO/CDPS0)


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SAP APO Planning Board

SAP APO Production Planning Interactive Production Planning DetailedScheduling Detailed Scheduling Planning Board/Variable view

(APO/CDPS0)


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SAP APO Planning Board (Legend)

SAP APO Production Planning Interactive Production Planning DetailedScheduling Detailed Scheduling Planning Board/Variable view(APO/CDPS0)


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DS Heuristics Features:Strategy settings

Depending on the heuristic, you can change the selected

strategy settings that the heuristic uses to schedule or

reschedule operations. Certain strategy settings are

permanently set by SAP and cannot be changed.

Planning period

The system uses heuristics to reschedule operations that

start in the planning period.


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DS Heuristic Activities1. If you want to start a heuristic on the DS planning

board, select the desired objects and call up the

heuristic by choosing FunctionsHeuristics. You can

change the settings for the heuristics on the DS planning

board by choosing SettingsHeuristics.

2. If you want to use a heuristic in the production planning

run, enter the heuristic and the objects for which you

want to execute the heuristic in the correspondingprocessing step in the production planning run.


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Homework for DS

1. Change demands for Distribution centers

2. Run network plan with multilevel heuristic

3. Review planning board

4. Define SNP deployment profile

5. Define transport load builder profile (TLB)

6. Assign TLB profile to the transportation lanes

7. Run deployment heuristics

Documents

EGN_5623 Detailed Scheduling