6B Scheduling
6B Scheduling
6B Scheduling
INDEX
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Operations Management Scheduling
1 Scheduling
Types of scheduling. 1-2
How scheduling fits in operations mgmt.
2 Scheduling customer demand. 3
6 Purpose of scheduling. 8
7 Scheduling method. 9
8 Scheduling activities. 10
9 Job dispatching. 11
10 Performance measures. 12
12 Johnson’s rule. 15
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Operations Management Scheduling
Scheduling
Types of Scheduling:
Scheduling:
Scheduling is allocation of resources over time to accomplish specific
tasks. It involves developing and assigning specific dates for the start and
completion of the necessary task or operations in a production shop floor. The
output plans indicated in master production schedules must be implemented on
a shop floor on a day to day basis.
Demand scheduling:
Demand scheduling is a type of scheduling whereby customers are
assigned to a definite time for order fulfillment. Customers are assigned to a
definite time for order fulfillment. It provides the capability to receive and
manage customer requirements as a time phased schedule of demand rather
then a series of separate sales order. This helps enterprise to track the activities
of the customers and thereby increase its own efficiency.
Workforce scheduling:
A type of scheduling that determines when employees work. It is the process
of balancing work to be completed with the resources available to compute the
work. It is very important to know the expected work load and resources to be
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Operations Management Scheduling
allocated accordingly. The amount of work may vary from day to day or minute
to minute.
Operations scheduling:
Operations As a Competitive
Weapon
Operations Strategy
Project Management
Process Strategy
Process Analysis
Process Performance and Quality
Constraint Management
Process Layout
Lean Systems
(1) Appointments:
Assign specific times for service to customers. A customer is asked to
come at a specific time.
E.G..: A medical clinic typically determines the employees work schedule
and then uses an appointment system to control the arrivals of patients in
accordance with the availability of employees.
(2) Reservations :
Reservations are used when the customer actually occupies or uses
facilities associated with the service. It is basically scheduling the time and date
in advanced for customers convenient.
E.G: Reservation done for airlines so that a customer can fly on the
scheduled time rather then last minute chaos or reservations of room scheduled
in a hotel in advance to avoid last minute search.
(3) Backlogs:
• The customer is given a due date for the fulfillment a product order, or
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Operations Management Scheduling
Scheduling Employees
Rotating schedule:
Rotating schedule is a schedule that rotates employees through a series
of workdays or hours.
E.G: on a shop floor workers who work on machines a kept to work on rotation
basis so that they don’t get stressed out. People working in textile miles or any
other industry general work on shift basis.
Fixed schedule:
Fixed schedule is the one that calls for each employee to work the same
days and hours each week.
E.G: in a office employees usually work on a fixed hours basis i.e. they usually
work on 8 to 8 time basis.
Constraints:
The technical constraints imposed on the workforce schedule are the
resources provided by the staffing plan and the requirements placed on the
operating system.
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Operations Management Scheduling
cancelled, etc.
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Operations Management Scheduling
Obtain quick feedback from shops regarding delays and interruptions which
Inputs of Scheduling
a) Performance Standard:
Performance standard is the first & foremost requirement of good
scheduling. Performance standard enables the scheduler to determine the
machine capacity in order to assign required machine hours for the various
operations. Good scheduling is always possible if the time study or
industrial engineering dept exist in the plant. The approx time estimate can
be prepared by breaking the task into elements & then estimating time for
each manual & machine element.
b) Unit of Measurement:
Unit of measurement refers to the unit in which loading &
scheduling is to be extended. This unit of measurement is usually different
for different industries. Industries such as sugar, cement, fertilizers, steel
general use weight (kg/tons) as unit of measurement while in textile mills, it
is in length (meters). The most common unit of measurement in engineering
firms is “man-hour” & “machine-hours”.
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Operations Management Scheduling
e) Overlapping of Operations:
Overlapping of operations is yet another useful consideration
in scheduling. Overlapping of operations refers to running of a job
simultaneously on more than one machine & it occurs in jobs which involves
two or more operation. It helps to reduce manufacturing time & hence the
delivery period of customers.
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Operations Management Scheduling
WHY SCHEDULING?
Every order whether it is from customer or from the assembly benches
must be completed on or before the contracted date. To ensure that the
delivery date is met, each component entering the assembly should be made
available on time. Determines start and completion data of each operations
Scheduling is the process of fitting a shop order into committed time
available for machine or group of machines required for the manufacture of
time and within the total time which is no greater than the promised delivery
period.
PURPOSE OF SCHEDULING
Scheduling of operations is essential for all firms as it helps them
maximize customer satisfaction and minimize service delays. Proper
scheduling enables firms allocate their production capacity to meet their
customer requirements on time. If a firm schedules too much capacity, the
facilities may remain idle, resulting in wastage of resources. Likewise,
scheduling low capacity may result in incomplete jobs at the specified time
resulting in poor service to customers. So firms should develop their
schedules in such a way that the optimum amount of resources is allocated
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Operations Management Scheduling
SCHEDULING METHODS
Forward scheduling
Forward scheduling is a scheduling method in which actual
production activities start when a job order is received. In this method, the
operations manager schedules each operation forward in time starting from
the date of production. Using forward scheduling, the operations manager
determines the start and finish times for jobs to be done by assigning them to
the earliest available time slots at the work center. As the jobs start at the
earliest possible time, they are completed before they are required at
subsequent work centres.Therefore; the work-in-process inventory level is
high in the forward scheduling method.
Forward scheduling is used in fabrication operations where the products
are so customized that customers specify the product specifications.
Backward Scheduling
The backward scheduling method schedules orders according to their due
dates. The operations manager obtains the due dates for the job orders and
develops the schedule backwards, thereby determining the latest point when
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Operations Management Scheduling
the production activity can be started in order to complete the order on time.
In this scheduling, the start and finish times of the jobs are assigned
according to the latest available time slot. For example, the Annual General
Meeting of a firm is scheduled to be held on 30th December. So the
operations manager can schedule the required operations backward in such
a way that they will be completed by the due date. This scheduling can also
be done in service organizations when the demand for services can be
anticipated earlier.
Scheduling Activities
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Operations Management Scheduling
The rules that specify the job processing sequence when several jobs
are waiting in line at a workstation.
Total Shop Time = Setup, processing, move, and expected waiting times of
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Operations Management Scheduling
Performance Measures
Make span:
The total amount of time required to complete a group of jobs.
The amount of time by which a job missed its due date or the percentage
of total jobs processed over some period of time that missed their due dates.
Work in progress is any job that is waiting in line, moving from one
operation to the next, being delayed, being processed, or residing in a semi-
finished state.
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Operations Management Scheduling
Total inventory:
Utilization:
Gantt Charts
Gantt chart:
Gantt Charts are simple bar charts that can be used to schedule any type of
operation
The chart takes two basic forms: (1) the job or activity progress chart, and
(2) the workstation chart.
The Gantt progress chart graphically displays the current status of each job
or activity relative to its scheduled completion date.
The Gantt workstation chart shows the load on the workstations and the
nonproductive time.
Gantt Progress Chart:
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Operations Management Scheduling
Johnson’s Rule
Johnson’s rule:
A procedure that minimizes makes span when scheduling a group of
jobs on two workstations.
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Step 1.
Find the shortest processing time among the jobs not yet scheduled.
If two or more jobs are tied, choose one job arbitrarily.
Step 2.
If the shortest processing time is on workstation 1, schedule the
corresponding job as early as possible. If the shortest processing time is
on workstation 2, schedule the corresponding job as late as possible.
Step 3.
Eliminate the last job scheduled from further consideration. Repeat
steps 1 and 2 until all jobs have been scheduled.
Time (hr)
Motor Workstation 1 Workstation
2 M1 12 22
M2 4 5
M3 5 3
M4 15 16
M5 10 8
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Operations Management Scheduling
Job Operation
Job operations refer to the manufacturing of products or services on
the basis of orders. They are scheduled as per requirements of customers.
These operations involve the production of products and services in low
volume. There is considerable variation in the materials used. Gantt charts,
job sequencing methods and critical ratio are some methods used.
Repetitive Operations
Repetitive operations are also called as continuous operation; normally
involve mass production of a product or services. Therefore there is little
variation in the production process, in this operation the labor is trained
and the equipment is designed for a narrow range of application. It
minimizes idle time and maximizes the flow of inventory. Therefore the
scheduling for these activities focuses on synchronization between customers
demand and production activities. JIT and queuing analysis are used.
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Operations Management Scheduling
Flextime:
In this approach the employees are given the option of choosing their work
timings, provided that specified no. of hours is completed in a week.
Flex tour:
In this approach, employees are given some freedom in choosing their start
time, but they must work each day for eight hours.
Staggered times:
Here employees are given a option to select their work timing from a list of
shifts.
Compressed workweek:
In this approach employees have an option of working ten hours a day for
four days a week.
And
Part time
Service Operation
The scheduling of services operation is different from manufacturing
operations for two reasons
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Firms normally meet the peak demand by engaging part time workers.
Therefore different managers use different methods to deal with constraints.
For example an airline service provider my reduce the travel fare in the off
– season to create more demand.
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Operations Management Scheduling
When a workstation becomes idle, the priority rule is applied to the jobs
waiting for that operation, and the job with the highest priority is selected.
When that operation is finished, the job is moved to the next operation in
its routing, where it waits until it again has the highest priority.
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Operations Management Scheduling
Single-dimension rules:
A set of rules such as FCFS, EDD, and SPT, that bases the priority
of a job on a single aspect of the job, such as arrival time at the workstation,
the due date, or the processing time.
Multiple-dimension rules:
It is a set of rules that apply to more than one aspect of a job.
Labor-limited Environments
The limiting resource thus far has been the number of machines or
workstations available. A more typical constraint is the amount of labor
available.
Labor-limited environment:
It is an environment in which the resource constraint is the amount of
labor available, not the number of machines or workstations.
1. Assign personnel to the workstation with the job that has been in the
system longest.
2. Assign personnel to the workstation with the most jobs waiting for
processing.
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Operations Management Scheduling
Bibliography
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Reference Book:
Websites search:
www.yahoo.co.in
www.google.com
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