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SCHEDULING:High-Volume Systems, Load Chart, Hungarian Method

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Production and Operations Management ­MGT613
VU
Lesson 41
SCHEDULING
Learning Objectives
After completing the introductory discussion on Scheduling, the students would be able to understand
what scheduling is and how important it is to high volume and intermediate volume systems. It would
also help them to learn how to address scheduling needs in Job shops. The students would also learn the
use and interpretation of Gantt Charts. They would also use Assignment method for loading along with
common Priority Rules. They would also learn the common and unique scheduling problems in Service
Systems.
Scheduling
Scheduling: Scheduling is an important tool for manufacturing and service industries where it can have
a major impact on the productivity of a process. In manufacturing, the purpose of scheduling is to
minimize the production time and costs, by telling a production facility what to make, when, with which
staff, and on which equipment. Similarly, scheduling in service industries, such as airlines and public
transport, aim to maximize the efficiency of the operation and reduce costs.
Scheduling
Modern computerized scheduling tools greatly outperform older manual scheduling methods. This
provides the production scheduler with powerful graphical interfaces which can be used to visually
optimize real-time work loads in various stages of the production, and pattern recognition allows the
software to automatically create scheduling opportunities which might not be apparent without this view
into the data. For example, an airline might wish to minimize the number of airport gates required for its
aircraft, in order to reduce costs, and scheduling software can allow the planners to see how this can be
done, by analyzing time tables, aircraft usage, or the flow of passengers.
Scheduling
Companies use backward and forward scheduling to plan their human and material resources. Backward
scheduling is planning the tasks from the due date to determine the start date and/or any changes in
capacity required, whereas forward scheduling is planning the tasks from the start date to determine the
shipping date or the due date.
Benefits of Scheduling
Scheduling: Establishing the timing of the use of equipment, facilities and human activities in an
organization
1. Effective scheduling can yield
2. Cost savings
3. Increases in productivity
The benefits of production scheduling include:
1. Process change-over reduction
2. Inventory reduction, leveling
3. Reduced scheduling effort
4. Increased production efficiency
5. Labor load leveling
6. Accurate delivery date quotes
7. Real time information
High-Volume Systems
1. Flow system: High-volume system with Standardized equipment and activities
2. Flow-shop scheduling: Scheduling for high-volume flow system
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Production and Operations Management ­MGT613
VU
Work Center #1
Work Center #2
Output
Scheduling Manufacturing Operations
High-volume
Intermediate-
volume
Low-volume
Service
operations
High-Volume Success Factors
Process and product design
Preventive maintenance
Rapid repair when breakdown occurs
Optimal product mixes
Minimization of quality problems
Reliability and timing of supplies
Intermediate-Volume Systems
Outputs are between standardized high-volume systems and made-to-order job shops
Run size, timing, and sequence of jobs
Economic run size:
2DS
p
Q0 =
p-u
H
Scheduling Low-Volume Systems
Loading - assignment of jobs to process centers
Sequencing - determining the order in which jobs will be processed
Job-shop scheduling
Scheduling for low-volume
systems with many
variations
in requirements
Gantt Load Chart
Gantt chart - used as a visual aid for loading and scheduling
Load Chart
Load chart ­ A type of Gantt Chart that shows the loading and idle times for a group of machines or list
of departments
Work
Mon.
Tues.
Wed.
Thurs.
Fri.
Center
1
Job 3
Job 4
2
Job 3
Job 7
3
Job 1
Job 6
Job 7
4
Job 10
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Production and Operations Management ­MGT613
VU
Schedule chart ­ A type of Gantt Chart that shows the orders or jobs in progress and whether they are
on schedule or not.
Input/Output Control Chart ­ A type of Control Chart that shows management of work flow and queues
at the work centers
Loading Types
The common types of loading include the following
1. Infinite loading
2. Finite loading
3. Vertical loading
4. Horizontal loading
5. Forward scheduling
6. Backward scheduling
7.  Schedule chart
We now briefly discuss these type of Loading
1. Infinite loading. Jobs are assigned to work centers without regard to the capacity of the work
center.
2. Finite loading Jobs are assigned to work centers with regard to the capacity of the work center
and job processing times.
3. Vertical loading: Loading jobs at a work center, job by job, usually according to some priority
criterion, using infinite loading i.e. Jobs are assigned to work centers without regard to the
capacity of the work center.
4. Horizontal loading: Loading each job on all work centers it will require, then the next job on all
work centers, according to some priority, using finite loading i.e. Jobs are assigned to work
centers with regard to the capacity of the work center and job processing times.
5. Forward scheduling: Scheduling ahead, from some point in time
6. Backward scheduling: Scheduling by working backwards from the due date
7. Schedule chart A Gantt chart that shows the orders or jobs in progress and whether they are on
schedule or not.
Assignment Method of Linear Programming
Assignment Model is a type of linear programming model for optimal assignment of tasks and resources
Hungarian method is the method of assigning jobs by a one for one matching to identify the lowest cost
solution
Let's take a step by step approach to understand and make use of Hungarian Method
Hungarian Method
First of all, acquire the relevant cost information and arrange it in tabular form
Second, obtain the Row Reduction; this is obtained by subtracting the smallest number in each row
from every number in the row. Enter the results in a new table.
Third, Obtain the Column Reduction by subtracting the smallest number in each column of the new
table from every number in the column.
Fourth, test whether an optimum assignment can be made. You do this by determining the minimum
number of lines needed to cover ( i.e.) cross out all zeros. If the number of lines equal the numbers
of row, an optimum assignment is possible. IN that case move to final step.
Fifth, if the numbers of lines is less than the number of rows, modify the table in the following
manner
o  Subtract the smallest uncovered number from every uncovered number in the table.
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Production and Operations Management ­MGT613
VU
Add the smallest uncovered number to the numbers at the intersections of covering
o
lines
Numbers crossed out but not at intersections of cross out lines carry over unchanged to
o
the next table.
Sixth, Repeat steps fourth and fifth unless an Optimal table is obtained
Seventh, make the assignments. Begin with rows or columns with only one zero. Match items that
have zeros, using only one match for each row and each column. Cross out both the row and column
for each row.
Hungarian Method Example
Please refer to the matrix which shows Jobs 1,2,3 and 4 with Machines A, B, C and D.
JOBS
A
B
C
D
1
8
6
2
4
2
6
7
11
10
3
3
5
7
6
4
5
10
12
9
Please apply the Hungarian Method to make appropriate assignments.
Select the Row Minimum
MACHINE
JOBS
A
B
C
D
ROW MIN
1
8
6
2
4
2
2
6
7
11
10
6
3
3
5
7
6
3
4
5
10
12
9
5
Subtract the smallest number in reach row
To form a new table and select column minimum
MACHINE
JOBS
A
B
C
D
1
6
4
0
2
2
0
1
5
4
3
0
2
4
3
4
0
5
7
4
COL MIN
0
1
0
2
Subtract the smallest number in reach column & Enter the results to form a new table
MACHINE
JOBS
A
B
C
D
1
6
3
0
0
2
0
0
5
2
3
0
1
4
1
4
0
4
7
2
Determine the minimum number of lines needed to cross Out all zeros. Here we have three lines only
and rows are 4, so the solution is not optimal
Hungarian Method Example
Subtract the smallest value that has not been crossed out from every number that has not been crossed
out (1 here) and add this to numbers that are at intersections of covering lines
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Production and Operations Management ­MGT613
VU
MACHINE
JOBS
A
B
C
D
1
6
3
0
0
2
0
0
5
2
3
0
1
4
1
4
0
4
7
2
MACHINE
JOBS
A
B
C
D
1
6+1=7
3
0
0
2
0+1=1
0
5
2
3
0
0
3
0
4
0
3
6
1
Determine the minimum number of lines needed to cross Out all 0 ( 4), since this equals the number of
rows , we obtain the optimum assignment.
MACHINE
JOBS
A
B
C
D
1
7
3
0
0
2
1
0
5
2
3
0
0
3
0
4
0
3
6
1
Make the assignments, start with rows and columns with Only one 0. Match jobs with machines that
have 0 costs.
MACHINE
JOBS
A
B
C
D
1
7
3
0
0
2
1
0
5
2
3
0
0
3
0
4
0
3
6
1
The assignment according to Hungarian Method is therefore
A4, 2B,1C AND 3D
Sequencing
Sequencing: Determine the order in which jobs at a work center will be processed.
Workstation: An area where one person works, usually with special equipment, on a specialized job.
Summary
Scheduling is the timing and coordination of Operations. Scheduling problems differ in nature because
of the system being designed for high volume, intermediate or low volume flow. In our next lecture we
will discuss its complementary and supplementary concept of Sequencing.
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Table of Contents:
  1. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT
  2. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT:Decision Making
  3. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT:Strategy
  4. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT:Service Delivery System
  5. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT:Productivity
  6. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT:The Decision Process
  7. INTRODUCTION TO PRODUCTION AND OPERATIONS MANAGEMENT:Demand Management
  8. Roadmap to the Lecture:Fundamental Types of Forecasts, Finer Classification of Forecasts
  9. Time Series Forecasts:Techniques for Averaging, Simple Moving Average Solution
  10. The formula for the moving average is:Exponential Smoothing Model, Common Nonlinear Trends
  11. The formula for the moving average is:Major factors in design strategy
  12. The formula for the moving average is:Standardization, Mass Customization
  13. The formula for the moving average is:DESIGN STRATEGIES
  14. The formula for the moving average is:Measuring Reliability, AVAILABILITY
  15. The formula for the moving average is:Learning Objectives, Capacity Planning
  16. The formula for the moving average is:Efficiency and Utilization, Evaluating Alternatives
  17. The formula for the moving average is:Evaluating Alternatives, Financial Analysis
  18. PROCESS SELECTION:Types of Operation, Intermittent Processing
  19. PROCESS SELECTION:Basic Layout Types, Advantages of Product Layout
  20. PROCESS SELECTION:Cellular Layouts, Facilities Layouts, Importance of Layout Decisions
  21. DESIGN OF WORK SYSTEMS:Job Design, Specialization, Methods Analysis
  22. LOCATION PLANNING AND ANALYSIS:MANAGING GLOBAL OPERATIONS, Regional Factors
  23. MANAGEMENT OF QUALITY:Dimensions of Quality, Examples of Service Quality
  24. SERVICE QUALITY:Moments of Truth, Perceived Service Quality, Service Gap Analysis
  25. TOTAL QUALITY MANAGEMENT:Determinants of Quality, Responsibility for Quality
  26. TQM QUALITY:Six Sigma Team, PROCESS IMPROVEMENT
  27. QUALITY CONTROL & QUALITY ASSURANCE:INSPECTION, Control Chart
  28. ACCEPTANCE SAMPLING:CHOOSING A PLAN, CONSUMER’S AND PRODUCER’S RISK
  29. AGGREGATE PLANNING:Demand and Capacity Options
  30. AGGREGATE PLANNING:Aggregate Planning Relationships, Master Scheduling
  31. INVENTORY MANAGEMENT:Objective of Inventory Control, Inventory Counting Systems
  32. INVENTORY MANAGEMENT:ABC Classification System, Cycle Counting
  33. INVENTORY MANAGEMENT:Economic Production Quantity Assumptions
  34. INVENTORY MANAGEMENT:Independent and Dependent Demand
  35. INVENTORY MANAGEMENT:Capacity Planning, Manufacturing Resource Planning
  36. JUST IN TIME PRODUCTION SYSTEMS:Organizational and Operational Strategies
  37. JUST IN TIME PRODUCTION SYSTEMS:Operational Benefits, Kanban Formula
  38. JUST IN TIME PRODUCTION SYSTEMS:Secondary Goals, Tiered Supplier Network
  39. SUPPLY CHAIN MANAGEMENT:Logistics, Distribution Requirements Planning
  40. SUPPLY CHAIN MANAGEMENT:Supply Chain Benefits and Drawbacks
  41. SCHEDULING:High-Volume Systems, Load Chart, Hungarian Method
  42. SEQUENCING:Assumptions to Priority Rules, Scheduling Service Operations
  43. PROJECT MANAGEMENT:Project Life Cycle, Work Breakdown Structure
  44. PROJECT MANAGEMENT:Computing Algorithm, Project Crashing, Risk Management
  45. Waiting Lines:Queuing Analysis, System Characteristics, Priority Model