OPERATIONS PLANNING AND SCHEDULING
Master scheduling
Material requirements planning
Order schedulingWeekly workforce andcustomer scheduling
Daily workforce
Process planning
Strategic capacity planning
Sales and operations (aggregate) planning
Longrange
Intermediaterange
Shortrange
ManufacturingServices
Sales plan Aggregate operations plan
Forecasting & demand management
Required Inputs to the Production Planning System
Planning for
production
External capacity
Competitors’behavior
Raw material availability
Market demand
Economic conditions
Currentphysical capacity
Current workforce
Inventory levels
Activities required for production
External to firm
Internal to firm
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A Basic Frame Work
Customer Orders Demand Management
Aggregate Production Plannig
Master Production Schedule
Material Requirement Planning
Detailed Capacity Planning
Purchasing
Vendors
Engineering Design
Engineering Changes
Bill of Materials
Process Planning
Rough-Cut CapacityPlanning
Inventory Management
Shop-FloorControl
Finished Products
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AGGREGATE PRODUCTION PLANNING:
In a high-variety, discrete manufacturing environment, demand for product may fluctuate considerably.
On the other end, the resources of the company (number of machines, number of workers, etc.) remain constant during the planning horizon (normally 12 months).
The best approach to obtain feasible solutions is to aggregate the information being processed.
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MASTER PRODUCTION SCHEDULE:
The primary use of an aggregate production plan is to level the production schedule so that the production costs are minimized.
However, the output of an aggregate plan does not indicate individual product. This means that the aggregated plan must be disaggregated into individual product. The result of such a disaggregation methodologies is what is known as master production schedule.
Overview of the MRP System
Product Structure File
Master Production Schedule
Inventory Master File
Material Requirements
Planning
Manufacturing Orders
Purchase Orders
Various Reports
What is MRP?Computerized Inventory Control
Production Planning System
Management Information System
Manufacturing Control System
When to use MRPJob Shop ProductionComplex ProductsAssemble-to-Order Environments
Discrete and Dependent Demand Items
What can MRP do?Reduce Inventory
LevelsReduce Component
ShortagesImprove Delivery
PerformanceImprove Customer
ServiceImprove ProductivitySimplified and
Accurate Scheduling
Reduce Purchasing Cost
Improve Production Schedules
Reduce Manufacturing Cost
Reduce Lead TimesLess Scrap and
ReworkHigher Production
Quality
What can MRP do?Improve
CommunicationImprove Plant
EfficiencyReduce Freight
CostReduction in
Excess Inventory
Reduce OvertimeImprove Supply
SchedulesImprove
Calculation of Material Requirements
Improve Competitive Position
Three Basic Steps of MRPIdentifying Requirements
Running MRP – Creating the Suggestions
Firming the Suggestions
Inventory Master FileOn-Hand QuantitiesOn-Order QuantitiesLot SizesSafety StockLead TimePast-Usage Figures
An ExampleResource Planning:Assume that a jewelry manufacturing
company decided to open three manufacturing sites (US, Ireland and Singapore).
Each plant is going to run one shift
except plating area which will be run 2 shifts due to high investment requirement.
Example Cont’dDemand Management: Demand is forecasted for different product families and different plants as follows: US plant Ireland plant Singapore
plant Earrings 300000units/yr 200000units/yr 150000units/yr Pendants 350000 225000 200000 Rings 150000 100000 75000
Example Cont’dProduction Plans: US Plant Months 1 2 3 4 5 6 7 8 9 10 11 12 Earring 20K 20K 20K 20K 20K 20K 30K 30K 30K 30K 30K 30K Pendant 20K 20K 20K 20K 20K 20K 30K 40K 40K 40K 40K 40K Ring 10K 10K 10K 10K 10K 10K 15K 15K 15K 15K 15K 15K PRODUCTION PLAN IS PREPARED FOR IRELAND AND SINGAPORE PLANTS AS WELL.
Example Cont’dDemand Management: Following manpower and resources requirements are estimated for each plant:
US plant Ireland plant Singapore plant
Manpower 300 200 150 Machine Type X
50
40
30
Machine Type Y
100
120
50
Machine Type Z
150
40
70
Example Cont’dMaster Production Schedule: US Plant – Earring Family – 1ST Month
Weeks 1 2 3 4 Gold Earring 1K 1K 1K 2K Gold Earring with red stone
1K 1K 2K 1K
Silver Earring 1K 2K 1K 1K Silver Earring with red stone
2K 1K 1K 1K
TOTAL 5K 5K 5K 5K MASTER SCHEDULE IS PREPARED FOR EACH MONTH (POSSIBLY FOR THE 1ST COUPLE OF MONTHS, NOT FOR THE ENTIRE YEAR) AND PRODUCT FAMILY.
Example Cont’dRough-cut Capacity Planning: Manpower and machine requirements are revised.
US plant Manpower 330 Machine Type X
55
Machine Type Y
95
Machine Type Z
190
Example Cont’dMaterials Planning: Detailed material plans are prepared for subassemblies and parts to be manufactured; components and raw materials to be purchased. Weeks 1 2 3 4 5 6 7 8 9 10 11 12 Gold 3kg 3kg 2.5kg 2.5kg … Silver 5kg 5kg 4kg 4kg … Red Stone
3K 2K 3K 2K …
Plated parts
5K 5K 5K 5K …
Example Cont’dCapacity Requirements Planning: Weeks 1 2 3 4 5 6 7 8 9 10 11 12 Manpower 320 310 330 322 … Machine X
52 55 60 57 …
Machine Y
90 92 98 95 …
Machine Z
178 163 172 170 …
Example Cont’dPurchasing: Contact vendors, evaluate quotes and cut purchase orders. Shop Floor Control: Assign parts to be plated to different plating lines Load manufacturing cells with products and determine start and completion times Cell1 Job1 Job 3 Job 7 Cell2 Job 2 Job 4 Cell3 Job 5 Job 8 Job 6 0 5hr 7 10 22 25 34 38
Planning vs. Control
planning no control yes
Plans
OK?
Stop
Revise
Repetitive
Matching PPC with the Needs of the Firm
Number ofSubparts
Seconds Minutes Days Weeks Months
Time between successive units Examples: Oil, food, drugs, watches, TV, trucks, planes,
houses, ships
Flow
Just-in-TimeMRP CPM/PERT
Matching PPC with the Needs of the Firm1. Flow-Oriented Manufacturing
SystemsVery short time between successive unitsA few components neededFlow rate is the measureEx: Chemical, food, petroleum
Matching PPC with the Needs of the Firm (Cont’d)2. Repetitive-Nature Manufacturing
SystemsShort time between successive unitsAssemble similar productsFlow Rate or Assembly Rate is the measureEx: Televisions, Radios, Watches, Cars
Matching PPC with the Needs of the Firm (Cont’d)3. Just-in-Time
High production volumeLow Product VarietyReduced Inventory and LeadtimeEx: Cars, Computers, Jewelry, Copy Machines
Matching PPC with the Needs of the Firm (Cont’d)4. Materials Requirements Planning
(MRP)Batch production High product varietyLow production quantity Ex: Electric Motors, Fans
Matching PPC with the Needs of the Firm (Cont’d)5. CPM/PERT
Long leadtimes Low production quantity Ex: Airplanes, ships
PPC Functions Material : Procurement, storage, inventory
control and issue Methods : Processes , operations and their
sequences. Machines and equipments : Selection of m/cs,
maintenance policies, loading of jobs and proper utilization.
Manpower : Manpower planning Routing : Sequence of operations to be
performed. (Route sheet – It defines each step of the production and lays down precise path or route through which product will flow during the conversion process)
Contd.. Estimating : Estimation of processing time
both set up time and operations times and establishing performance standards.
Loading and scheduling : Time table of production, priority sequencing and machine loading.
Dispatching : Execution of plan – production orders and instructions are released.
Expediting and progressing : Follow up or keeping track of progress providing feedback to the PPC manager to prompt review of targets and schedules
Contd..
Inspection : Checking quality in production and of evaluating the efficiency of the processes, methods and workers so that improvements can be to achieve the desired level of quality.
Evaluating and controlling : To improve the performance
Gantt Chart
Operations Scheduling
Work CenterA work center is an area in a business
in which productive resources are organized and work is completed
Can be a single machine, a group of machines, or an area where a particular type of work is done
Capacity and Scheduling
Infinite loadingFinite loadingForward schedulingBackward scheduling
Typical Scheduling and Control Functions
Allocating orders, equipment, and personnel
Determining the sequence of order performance
Initiating performance of the scheduled work
Shop-floor control
Work-Center Scheduling Objectives
Meet due dates
Minimize lead time
Minimize setup time or cost
Minimize work-in-process inventory
Maximize machine utilization
Priority Rules for Job Sequencing 1. First-come, first-served
(FCFS)
2. Shortest operating time (SOT)
3. Earliest due date first (EDD)
Example of Job Sequencing: First-Come First-Served
Jobs (in order Processing Due Date Flow Timeof arrival) Time (days) (days hence) (days)
A 4 5 4B 7 10 11C 3 6 14D 1 4 15
Answer: FCFS Schedule
Jobs (in order Processing Due Dateof arrival) Time (days) (days hence)
A 4 5B 7 10C 3 6D 1 4
Suppose you have the four jobs to the right arrive for processing on one machine
What is the FCFS schedule?
No, Jobs B, C, and D are going to be late
Do all the jobs get done on time?
Example of Job Sequencing: Shortest Operating Time
Jobs (in order Processing Due Dateof arrival) Time (days) (days hence)
A 4 5B 7 10C 3 6D 1 4
Answer: Shortest Operating Time Schedule
Jobs (in order Processing Due Date Flow Timeof arrival) Time (days) (days hence) (days)
D 1 4 1C 3 6 4A 4 5 8B 7 10 15
Suppose you have the four jobs to the right arrive for processing on one machine
What is the SOT schedule?
No, Jobs A and B are going to be late
Do all the jobs get done on time?
Example of Job Sequencing: Earliest Due Date First
Jobs (in order Processing Due Dateof arrival) Time (days) (days hence)
A 4 5B 7 10C 3 6D 1 4
Answer: Earliest Due Date FirstJobs (in order Processing Due Date Flow Time
of arrival) Time (days) (days hence) (days)D 1 4 1A 4 5 5C 3 6 8B 7 10 15
Suppose you have the four jobs to the right arrive for processing on one machine
What is the earliest due date first schedule?
No, Jobs C and B are going to be late
Do all the jobs get done on time?
Example of Job Sequencing: Johnson’s Rule (Part 1)Suppose you have the following five jobs with time requirements in two stages of production. What is the job sequence using Johnson’s Rule?
Time in HoursJobs Stage 1 Stage 2 A 1.50 1.25 B 2.00 3.00 C 2.50 2.00 D 1.00 2.00
Example of Job Sequencing: Johnson’s Rule (Part 2)First, select the job with the smallest time in either stage.
That is Job D with the smallest time in the first stage. Place that job as early as possible in the unfilled job sequence below.
Drop D out, select the next smallest time (Job A), and place it 4th in the job sequence.
Drop A out, select the next smallest time. There is a tie in two stages for two different jobs. In this case, place the job with the smallest time in the first stage as early as possible in the unfilled job sequence.
Then place the job with the smallest time in the second stage as late as possible in the unfilled sequence.
Job Sequence 1 2 3 4Job Assigned D A B C
Time in HoursJobs Stage 1 Stage 2 A 1.50 1.25 B 2.00 3.00 C 2.50 2.00 D 1.00 2.00
SCHEDULING N NUMBER ON JOBS ON N NO OF MACHINES
Assignment method – transportation method of linear programming.
SCHEDULING N NUMBER ON JOBS ON N NO OF MACHINES
Computer simulation
Shop-Floor Control:Major Functions
1. Assigning priority of each shop order
2. Maintaining work-in-process quantity information
3. Conveying shop-order status information to the office
Shop-Floor Control:Major Functions (Continued)
4. Providing actual output data for capacity control purposes
5. Providing quantity by location by shop order for WIP inventory and accounting purposes
6. Providing measurement of efficiency, utilization, and productivity of manpower and machines
Tools for Shop floor controlDaily dispatch listStatus and exception reports,
◦Anticipated delay report,◦Scrap reports◦Rework reports◦Performance summary reports◦Shortage listInput/output control report- monitor
workload capacity relationship
Input/Output Control
Planned input should never exceed planned output
Focuses attention on bottleneck work centers
Input OutputWorkCenter
Principles of Work Center Scheduling
1. There is a direct equivalence between work flow and cash flow
2. The effectiveness of any job shop should be measured by speed of flow through the shop
3. Schedule jobs as a string, with process steps back-to-back
4. A job once started should not be interrupted
Principles of Job Shop Scheduling
5. Speed of flow is most efficiently achieved by focusing on bottleneck work centers and jobs
6. Reschedule every day7. Obtain feedback each day on
jobs that are not completed at each work center
8. Match work center input information to what the worker can actually do
Principles of Job Shop Scheduling (Continued)
9. When seeking improvement in output, look for incompatibility between engineering design and process execution
10. Certainty of standards, routings, and so forth is not possible in a job shop, but always work towards achieving it
Personnel Scheduling in Services
Scheduling consecutive days off
Scheduling daily work times
Scheduling hourly work times