Course: Operations Management

American International University-Bangladesh

SCHEDULINGSCHEDULING

Scheduling is establishing the timing of the use of equipment, Scheduling is establishing the timing of the use of equipment, facilities and human activities in an organizationfacilities and human activities in an organization

Effective scheduling can save cost and increase productivityEffective scheduling can save cost and increase productivity

• In educational institutions, scheduling can reduce the need for expansion In educational institutions, scheduling can reduce the need for expansion of facilitiesof facilities

Effective scheduling can give a company competitive Effective scheduling can give a company competitive advantageadvantage

The objectives of scheduling are to achieve trade - offs among The objectives of scheduling are to achieve trade - offs among efficient utilization of staff, equipment and facilities, and efficient utilization of staff, equipment and facilities, and minimization of customer waiting time, cost, inventories and minimization of customer waiting time, cost, inventories and process timesprocess times

2

SCHEDULING IN HIGH VOLUME SYSTEMSSCHEDULING IN HIGH VOLUME SYSTEMS

Scheduling encompasses allocating workloads to specific Scheduling encompasses allocating workloads to specific work centers and determining the sequence in which work centers and determining the sequence in which operations to be performedoperations to be performed

High volume systems are characterized by standardized High volume systems are characterized by standardized equipment and activities that provide highly similar equipment and activities that provide highly similar operationsoperations

Automobiles, personal computers, toy, television etc.Automobiles, personal computers, toy, television etc.

High volume system with standardized equipment and High volume system with standardized equipment and activities is also known as activities is also known as Flow SystemFlow System

Scheduling for low volume systems with many variations in Scheduling for low volume systems with many variations in requirements is calledrequirements is called Job Shop SchedulingJob Shop Scheduling

Process and product designProcess and product design - - Cost and manufacturability is Cost and manufacturability is important as well as achieving a smooth flow through the systemimportant as well as achieving a smooth flow through the system

Preventive maintenancePreventive maintenance - - Keeping equipment in good operating Keeping equipment in good operating order can minimize breakdowns that would disrupt the flow of workorder can minimize breakdowns that would disrupt the flow of work

Rapid repair when breakdown occursRapid repair when breakdown occurs - - This require specialists This require specialists and stocks of spare partsand stocks of spare parts

Optimal product mixesOptimal product mixes - - Optimal blends of inputs to achieve Optimal blends of inputs to achieve desired outputs at minimal costdesired outputs at minimal cost

Minimization of quality problemsMinimization of quality problems - - Quality problems can be Quality problems can be extremely disruptive, requiring shutdowns while problems are resolvedextremely disruptive, requiring shutdowns while problems are resolved

Reliability and timing of suppliesReliability and timing of supplies - - Shortage of material can Shortage of material can disrupt the operation and excess storage can increase carrying costdisrupt the operation and excess storage can increase carrying cost

SUCCESS IN HIGH VOLUME SYSTEMSSUCCESS IN HIGH VOLUME SYSTEMS

SCHEDULING IN LOW VOLUME SYSTEMSSCHEDULING IN LOW VOLUME SYSTEMS

Scheduling for low volume systems with many variations in Scheduling for low volume systems with many variations in requirements is calledrequirements is called Job Shop SchedulingJob Shop Scheduling

The assignment of jobs to processing centers is called The assignment of jobs to processing centers is called LoadingLoading

Jobs are assigned to work centers without regard to the Jobs are assigned to work centers without regard to the capacity of the work center. It is called capacity of the work center. It is called Infinite LoadingInfinite Loading

Jobs are assigned to work centers taking into account the Jobs are assigned to work centers taking into account the work center capacity and job processing times. It is called work center capacity and job processing times. It is called Finite LoadingFinite Loading

Determining the order in which jobs at work center will be Determining the order in which jobs at work center will be processed is called Sequencingprocessed is called Sequencing

SEQUENCINGSEQUENCING

SequencingSequencing is determining the order in which jobs at a is determining the order in which jobs at a work center will be processedwork center will be processed

An area where one or a few workers and / or machines An area where one or a few workers and / or machines perform similar work is called perform similar work is called WorkstationWorkstation

Simple heuristics used to select the order in which jobs will Simple heuristics used to select the order in which jobs will be processed is called be processed is called Priority RulesPriority Rules

FCFS - First Come, First ServedFCFS - First Come, First Served

SPT - Shortest Processing TimeSPT - Shortest Processing Time

EDD - Earliest Due DateEDD - Earliest Due Date

CR - Critical RatioCR - Critical Ratio

S/O - Slack per OperationS/O - Slack per Operation

Rush - EmergencyRush - Emergency

7

PRIORITY RULESPRIORITY RULES

Everything is# 1 Priority

PERFORMANCE MEASURES OF SEQUENCEPERFORMANCE MEASURES OF SEQUENCE Job Flow TimeJob Flow Time - This is the length of time a job remains at - This is the length of time a job remains at

a particular work station. It includes processing time, waiting a particular work station. It includes processing time, waiting time, transportation time between operations and other time, transportation time between operations and other unexpected delay. The average flow time for a group of jobs unexpected delay. The average flow time for a group of jobs is equal to the total flow time (total cumulative) divided by is equal to the total flow time (total cumulative) divided by the number of jobs.the number of jobs.

Job LatenessJob Lateness – This is the length of time the job completion – This is the length of time the job completion date is expected to exceed the date the job was promised to date is expected to exceed the date the job was promised to a customer. If we only record differences for jobs with a customer. If we only record differences for jobs with completion times that exceed due dates, and assign zeros completion times that exceed due dates, and assign zeros to jobs that are early, the term we use to refer to that is to jobs that are early, the term we use to refer to that is Job Job TardinessTardiness. .

Makespan Makespan – Makespan is the total time needed to complete – Makespan is the total time needed to complete a group of jobs. It is the length of time between the start of a group of jobs. It is the length of time between the start of the first job in the group and the completion of the last job in the first job in the group and the completion of the last job in the group.the group.

Average number of jobs = Total flow time / Makespan

WHY SCHEDULING CAN BE DIFFICULTWHY SCHEDULING CAN BE DIFFICULT

An operation must deal with variability in setup times, An operation must deal with variability in setup times,

processing times, interruptions, and changes in the set of processing times, interruptions, and changes in the set of

jobs.jobs.

There is no method for identifying the optimal schedule, There is no method for identifying the optimal schedule,

and it would be virtually impossible to sort through the vast and it would be virtually impossible to sort through the vast

number of possible alternatives to obtain the best number of possible alternatives to obtain the best

schedule. It is a on going task for a manager.schedule. It is a on going task for a manager.

MINIMIZING SCHEDULING DIFFICULTIESMINIMIZING SCHEDULING DIFFICULTIES

Setting realistic due datesSetting realistic due dates

Forecasting on bottleneck operationsForecasting on bottleneck operations

Considering lot splitting for large jobsConsidering lot splitting for large jobs

MATHMATH

11