PRESENTATION ON

PRODUCTION SCHEDULING

PRESENTED BY:- POOJA HEMANGI KIRAN ANURADHA

ROADMAPWhat is schedulingExamplesObjectivesElementsPriority PlanningMaster Production scheduling (MPS)Objectives of MPSFunctions of MPSProblems of sequencing in scheduling

SCHEDULING

Scheduling is one of the most important elements in production planning.

Scheduling calls for through understanding of all aspects of the production process and is an outcome of the integration of the efforts of planners in the planning group and the people in the shop-floor.

Scheduling integrates the people, machine, materials, customer demands, and quality requirements in finalizing the priorities. Scheduling makes it possible by determining starting and completion data each of the operations.

EXAMPLES OF SCHEDULING

Timetabling Scheduling of the Computer :A number of different courses (tasks) have to be given using the PC room(resource)

Workforce scheduling : Assign shifts for nurses and doctors in a Hospital

Sports SchedulingDrug Scheduling

CONT……….

Scheduling effects from 2 environmental factors that are internal and external to the organization.

Internal environment External environment  

OBJECTIVES OF SCHEDULING

Maximize throughputBe predictable: Minimize overheadBalance resource useAchieve a balance between response and utilizationAvoid indefinite postponement Enforce PrioritiesGive preference to process holdingDegrade gracefully under heavy loads

ELEMENTS OF SCHEDULING

The processorsThe tasksThe processing timingsThe precedence relations

PRIORITY PLANNING

Planning is the process by which the elements required to perform a task are determined in advance of the job start. The process is as follows :

Operations soft constraintsManagement policy constraintsEngineering hard constraints

MASTER PRODUCTION SCHEDULING

Master scheduling is a part of scheduling.

A Master Production Schedule is a Schedule of the completions of the end items and these completions are very much planned in nature.

A MPS is also in management language referred to as the master of all the schedules as this schedule provides the production, planning, purchasing & top management, the most needed information required for planning and control of the whole manufacturing process or the operation.

OBJECTIVES OF MASTER SCHEDULING

Keeping the inventoriesSetting up the due dates for the availability of itemsMaintaining the customer serviceSetting proper schedules

FUNCTIONS OF MASTER SCHEDULING

Specifies planning periods as daily, weekly, or monthly.Group work order processingTracks accuracy of order forecasting as percentage.Classifies supply into types such as materials, purchased,

flow, work order, and transfer.Schedule can be edited, changed, or consolidated.

PROBLEMS OF SEQUENCING IN SCHEDULING

SHORTEST PROCESSING TIME (SPT)WEIGHTED SHORTEST PROCESSING TIME (WSPT)

EXAMPLE:- The data about a set of single operation jobs that is to be processed in

a CNC lathe and the processing times of the jobs in the given set of jobs are as given in table.

Find the optimal sequence which will minimize the mean flow time and also obtain the corresponding minimum mean flow time.

 Job, j Processing time, tj

1 7

2 18

3 6

4 8

5 12

SOLUTION:- For the given problem, the number of jobs is equal to

5. The jobs are arranged as per the SPT ordering.

Therefore, the job sequence which will minimize the mean flow time is 3-1-4-5-2.

Job, j Processing time, tj

3 6

1 7

4 8

5 12

2 18

CONTThe computation of flow time for the optimal sequence

(3-1-4-5-2). COMPUTATION FLOW TIME

Job, j Processing time, tj Completion time, cj(fj)

3 6 6

1 7 13

4 8 21

5 12 33

2 18 51

CONTSince the ready time rj is zero for all the values of j, the flow

time (fj) = cj for all j.

Therefore,

1/5 ∑ Fj = 1/5 (6+13+21+33+51)

= 1/5 (124) = 24.8 hours

Therefore, the optimal mean flow time = 24.8 hours.

WSPT

Example

Determine the sequence which will minimize the weighted flow time of this problem. Also find the corresponding weighted mean flow time.

Job, j Processing time, tj Weight , wj

1 7 1

2 18 2

3 6 1

4 8 2

5 12 3

SOLUTION:-

The weighted processing times of various jobs are summarized by using the formula tj/wj, j = 1,2,3,4, and 5

Job, j Processing time, tj

Weight , wj Tj/wj

1 7 1 7

2 18 2 9

3 6 1 6

4 8 2 4

5 12 3 4

CALCULATIONS OF WEIGHTED FLOW TIMES

Job, j Processing time, tj

Cj (Fj) Weight , wj Fjwj

4 8 8 2 16

5 12 20 3 60

3 6 26 1 26

1 7 33 1 33

2 18 51 2 102