4prod plan n control

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12-1 Aggregate Planning 1

Production planningand control


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12-4 Aggregate Planning

Cost control thro PPC Waiting time

Hunting time

Stalling

Interrupted workloads

Overtime

Reduce unproductive time of machines


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Timely

deliveries

Feedback

on status

Lower

capital

investment

Better

availability

Coordination

Effective

supervision

Job

satisfaction

Cost

reduction

Factors

of

production

Good

ROI

PPC


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Functions of PPC Sales enquiry

Technical feasibility

Produceability study

Cost estimates

Routing

Scheduling

Dispatch

Coordination


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Aggregate Planning


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Planning Horizon

Aggregate planning: Intermediate-rangecapacity planning, usually covering 2 to 12

months.

Short

range

Intermediate

range

Long range

Now 2 months 1 Year


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Short-range plans (Detailed plans) Machine loading

Job assignments

Intermediate plans (General levels) Employment

Output

Long-range plans

Long term capacity

Location / layout

Overview of Planning Levels


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12 11 A Pl


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Total cost of a plan Projected levels of inventory

Inventory

Output Employment

Subcontracting

Backordering

Aggregate Planning Outputs

12 12 A Pl i


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Aggregate Planning Strategies

Proactive Alter demand to match capacity

Reactive

Alter capacity to match demand

Mixed

Some of each

12 13 A Pl i


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Hire and layoff workers Overtime/slack time

Part-time workers

Inventories

Subcontracting

Capacity Options

12 14 A t Pl i


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Services occur when they are rendered

Demand for service can be difficult to predict

Capacity availability can be difficult to

predict

Labor flexibility can be an advantage in

services

Aggregate Planning in Services


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12 16 A t Pl i


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Master schedule: The result of disaggregatingan aggregate plan; shows quantity and timing

of specific end items for a scheduled horizon.

Rough-cut capacity planning: Approximatebalancing of capacity and demand to test the

feasibility of a master schedule.

Disaggregating the Aggregate Plan

12 17 Aggregate Planning


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CHAPTER

15

Scheduling

McGraw-Hill/Irwin

Operations Management, Eighth Edition, by William J. StevensonCopyright 2005 by The McGraw-Hill Companies, Inc. All rights reserved.



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Scheduling: Establishing the timing of theuse of equipment, facilities and human

activities in an organization

Effective scheduling can yield

Cost savings

Increases in productivity

Scheduling



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High-Volume Systems

Flow system: High-volume system withStandardized equipment and activities

Flow-shop scheduling: Scheduling for high-

volume flow system

WorkCenter #1 Work Center#2 Output


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Infinite loading

Finite loading

Vertical loading

Horizontal loading

Forward scheduling

Backward scheduling

Schedule chart

Loading



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Sequencing

Sequencing: Determine the order in whichjobs at a work center will be processed.

Workstation: An area where one personworks, usually with special equipment, on a

specialized job.



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Sequencing

Priority rules: Simple heuristicsused to select the order inwhich jobs will be processed.

Job time: Time needed forsetup and processing of a job.

Everything is

#1 Priority



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Johnsons Rule Conditions

Job time must be known and constant Job times must be independent of

sequence

Jobs must follow same two-step sequence

Job priorities cannot be used

All units must be completed at the firstwork center before moving to second



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Scheduling Difficulties

Variability in Setup times

Processing times

Interruptions Changes in the set of jobs

No method for identifying optimal schedule

Scheduling is not an exact science

Ongoing task for a manager


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gg g g

Master Scheduling

Master schedule Determines quantities needed to meet demand

Interfaces with

Marketing Capacity planning

Production planning

Distribution planning



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gg g g

Master Scheduler

Evaluates impact of new orders Provides delivery dates for orders

Deals with problems

Production delays Revising master schedule

Insufficient capacity


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gg g g

Types of Processes

Conversion (ex. Iron to steel)

Fabrication (ex. Cloth to clothes)

Assembly (ex. Parts to components)

Testing (ex. For quality of products)


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Capacity PlanningFor Products and Services



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Capacity Planning

Capacity is the upper limit or ceiling on theload that an operating unit can handle.

The basic questions in capacity handling are:

What kind of capacity is needed? How much is needed?

When is it needed?


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Capacity

Design capacity maximum output rate or service capacity an

operation, process, or facility is designed for

Effective capacity Design capacity minus allowances such as

personal time, maintenance, and scrap

Actual output rate of output actually achieved--cannot

exceed effective capacity.



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Efficiency and Utilization

Actual outputEfficiency =Effective capacity

Actual outputUtilization =

Design capacity

Both measures expressed as percentages



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Actual output = 36 units/day

Efficiency = = 90%Effective capacity 40 units/ day

Utilization = Actual output = 36 units/day= 72%

Design capacity 50 units/day

Efficiency/Utilization Example

Design capacity = 50 trucks/dayEffective capacity = 40 trucks/day

Actual output = 36 units/day



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Determinants of Effective Capacity

Facilities Product and service factors

Process factors

Human factors Operational factors

Supply chain factors

External factors


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Make or Buy

1. Available capacity2. Expertise

3. Quality considerations

4.Nature of demand5. Cost

6. Risk

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