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66

Process Selection and Facility Layout

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Learning ObjectivesLearning Objectives

Explain the strategic importance of process selection.

Explain the influence that process selection has on an organization.

Describe the basic processing types. Discuss automated approaches to

processing. Explain the need for management of

technology.

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Learning ObjectivesLearning Objectives

List some reasons for redesign of layouts. Describe the basic layout types. List the main advantages and

disadvantages of product layouts and process layouts.

Solve simple line-balancing problems. Develop simple process layouts.

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Process selection Deciding on the way production of goods or

services will be organized

Major implications Capacity planning Layout of facilities Equipment Design of work systems

IntroductionIntroduction

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Forecasting

Product andService Design

TechnologicalChange

CapacityPlanning

ProcessSelection

Facilities andEquipment

Layout

WorkDesign

Figure 6.1

Process Selection and Process Selection and System DesignSystem Design

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• Key aspects of process strategy– Capital intensive – equipment/labor

– Process flexibility

– Technology

– Adjust to changes

– Design

– Volume

– technology

Process StrategyProcess Strategy

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TechnologyTechnology

Technology: The application of scientific discoveries to the development and improvement of products and services and operations processes.

Technology innovation: The discovery and development of new or improved products, services, or processes for producing or providing them.

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Kinds of TechnologyKinds of Technology

Operations management is primarily concerned with three kinds of technology: Product and service technology Process technology Information technology

All three have a major impact on: Costs Productivity Competitiveness

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Technology Competitive Technology Competitive AdvantageAdvantage

Innovations in Products and services

Cell phones PDAs Wireless computing

Processing technology Increasing productivity Increasing quality Lowering costs

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Technology AcquisitionTechnology Acquisition

Technology can have benefits but … Technology risks include:

What technology will and will not do Technical issues Economic issues

Initial costs, space, cash flow, maintenance Consultants and/or skilled employees Integration cost, time resources Training, safety, job loss

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Variety How much

Flexibility What degree

Volume Expected output

Job Shop

Batch

Repetitive

Continuous

Process SelectionProcess Selection

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Job shop Small scale

Batch Moderate volume

Repetitive/assembly line High volumes of standardized goods or

services

Continuous Very high volumes of non-discrete goods

Process TypesProcess Types

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Process Type

Job Shop Appliance repairEmergency

room

Ineffective

Batch Commercialbaking

ClassroomLecture

Repetitive Automotiveassembly

Automaticcarwash

Continuous(flow)

Ineffective Steel ProductionWater purification

Figure 6.2

Product and Service Product and Service ProcessesProcesses

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Dimension

Job variety Very High Moderate Low Very low

Process flexibility

Very High Moderate Low Very low

Unit cost Very High Moderate Low Very low

Volume of output

Very High Low High Very low

Figure 6.2 (cont’d)Product – Process MatrixProduct – Process Matrix

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Product and Process ProfilingProduct and Process Profiling Process selection can involve substantial

investment in Equipment Layout of facilities

Product profiling: Linking key product or service requirements to process capabilities

Key dimensions Range of products or services Expected order sizes Pricing strategies Expected schedule changes Order winning requirements

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Automation: Machinery that has sensing and control devices that enables it to operate Fixed automation Programmable automation

AutomationAutomation

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• Computer-aided design and manufacturing systems (CAD/CAM)

• Numerically controlled (NC) machines

• Robot

• Manufacturing cell

• Flexible manufacturing systems(FMS)

• Computer-integrated manufacturing (CIM)

AutomationAutomation

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Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system

Product layouts

Process layouts

Fixed-Position layout

Combination layouts

Facilities LayoutFacilities Layout

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Objective of Layout DesignObjective of Layout Design

1. Facilitate attainment of product or service quality

2. Use workers and space efficiently3. Avoid bottlenecks4. Minimize unnecessary material handling

costs5. Eliminate unnecessary movement of workers

or materials6. Minimize production time or customer service

time7. Design for safety

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Requires substantial investments of money and effort

Involves long-term commitments Has significant impact on cost and

efficiency of short-term operations

Importance of Layout Importance of Layout DecisionsDecisions

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Inefficient operations

For Example:

High CostBottlenecks

Changes in the designof products or services

The introduction of newproducts or services

Accidents

Safety hazards

The Need for Layout DecisionsThe Need for Layout Decisions

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Changes inenvironmentalor other legalrequirements

Changes in volume ofoutput or mix of

products

Changes in methodsand equipment

Morale problems

The Need for Layout Design The Need for Layout Design (Cont’d)(Cont’d)

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Product layouts

Process layouts

Fixed-Position layout

Combination layouts

Basic Layout TypesBasic Layout Types

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Product layout Layout that uses standardized processing

operations to achieve smooth, rapid, high-volume flow

Process layout Layout that can handle varied processing

requirements Fixed Position layout

Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed

Basic Layout TypesBasic Layout Types

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Raw materialsor customer

Finished item

Station 2

Station 2

Station 3

Station 3

Station 4

Station 4

Material and/or labor

Station 1

Material and/or labor

Material and/or labor

Material and/or labor

Used for Repetitive or Continuous Processing

Figure 6.4Product LayoutProduct Layout

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High rate of output Low unit cost Labor specialization Low material handling cost High utilization of labor and equipment Established routing and scheduling Routing accounting and purchasing

Advantages of Product LayoutAdvantages of Product Layout

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Creates dull, repetitive jobs Poorly skilled workers may not maintain

equipment or quality of output Fairly inflexible to changes in volume Highly susceptible to shutdowns Needs preventive maintenance Individual incentive plans are

impractical

Disadvantages of Product LayoutDisadvantages of Product Layout

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1 2 3 4

5

6

78910

In

Out

Workers

Figure 6.6A U-Shaped Production LineA U-Shaped Production Line

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Dept. A

Dept. B Dept. D

Dept. C

Dept. F

Dept. E

Used for Intermittent processingJob Shop or Batch Processes

Process Layout(functional)

Figure 6.7Process LayoutProcess Layout

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Work Station 1

Work Station 2

Work Station 3

Figure 6.7 (cont’d)

Product Layout(sequential)

Used for Repetitive ProcessingRepetitive or Continuous Processes

Product LayoutProduct Layout

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Can handle a variety of processing requirements

Not particularly vulnerable to equipment failures

Equipment used is less costly Possible to use individual incentive

plans

Advantages of Process LayoutsAdvantages of Process Layouts

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In-process inventory costs can be high Challenging routing and scheduling Equipment utilization rates are low Material handling slow and inefficient Complexities often reduce span of supervision Special attention for each product or customer Accounting and purchasing are more involved

Disadvantages of Process Disadvantages of Process LayoutsLayouts

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Fixed Position LayoutsFixed Position Layouts

Fixed Position Layout: Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed.

Nature of the product dictates this type of layout Weight Size Bulk

Large construction projects

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Cellular Production Layout in which machines are grouped into

a cell that can process items that have similar processing requirements

Group Technology The grouping into part families of items with

similar design or manufacturing characteristics

Cellular LayoutsCellular Layouts

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Dimension Functional CellularNumber of moves between departments

many few

Travel distances longer shorter

Travel paths variable fixed

Job waiting times greater shorter

Throughput time higher lower

Amount of work in process

higher lower

Supervision difficulty higher lower

Scheduling complexity higher lower

Equipment utilization lower higher

Table 6.3Functional vs. Cellular LayoutsFunctional vs. Cellular Layouts

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Warehouse and storage layouts Retail layouts Office layouts Service layouts must be aesthetically

pleasing as well as functional

Service LayoutsService Layouts

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Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements.

Design Product Layouts: Line Design Product Layouts: Line BalancingBalancing

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Cycle time is the maximum time allowed at each workstation tocomplete its set of tasks on a unit.

Cycle TimeCycle Time

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D

OT = timecycle = CT

rateoutput Desired= D

dayper timeoperating OT

CT

OT = rateOutput

D

OT = timecycle = CT

rateoutput Desired= D

dayper timeoperating OT

CT

OT = rateOutput

Determine Maximum OutputDetermine Maximum Output

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task timeof sum = t

CT

t)( =N

Determine the Minimum Number Determine the Minimum Number

of Workstations Requiredof Workstations Required

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Precedence diagram: Tool used in line balancing to display elemental tasks and sequence requirements

A Simple Precedence Diagrama b

c d e

0.1 min.

0.7 min.

1.0 min.

0.5 min. 0.2 min.

Figure 6.11Precedence DiagramPrecedence Diagram

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Arrange tasks shown in Figure 6.10 into three workstations. Use a cycle time of 1.0 minute Assign tasks in order of the most number

of followers

Example 1: Assembly Line Example 1: Assembly Line BalancingBalancing

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Workstation

TimeRemaining Eligible

AssignTask

RevisedTime Remaining

StationIdle Time

1 1.0

0.9

0.2

a, c

c

none

a

c

-

0.9

0.2

0.2

2 1.0 b b 0.0 0.0

3 1.0

0.5

0.3

d

e

-

d

e

-

0.5

0.3 0.3

0.5

Example 1 SolutionExample 1 Solution

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Percent idle time = Idle time per cycle

(N)(CT)

Efficiency = 1 – Percent idle time

Calculate Percent Idle TimeCalculate Percent Idle Time

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Assign tasks in order of most following tasks. Count the number of tasks that follow

Assign tasks in order of greatest positional weight.

Positional weight is the sum of each task’s time and the times of all following tasks.

Some Heuristic (intuitive) Rules:

Line Balancing RulesLine Balancing Rules

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c d

a b e

f g h

0.2 0.2 0.3

0.8 0.6

1.0 0.4 0.3

Example 2Example 2

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Station 1 Station 2 Station 3 Station 4

a b ef

d

g h

c

Solution to Example 2Solution to Example 2

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1 min.2 min.1 min.1 min. 30/hr. 30/hr. 30/hr. 30/hr.

Bottleneck

Bottleneck WorkstationBottleneck Workstation

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Parallel WorkstationsParallel Workstations

1 min.

2 min.

1 min.1 min. 60/hr.

30/hr. 30/hr.

60/hr.

2 min.

30/hr.30/hr.

Parallel Workstations

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Information Requirements:

1. List of departments

2. Projection of work flows

3. Distance between locations

4. Amount of money to be invested

5. List of special considerations

6. Location of key utilities

Designing Process LayoutsDesigning Process Layouts

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1 3 2

30

170 100

A B C

Figure 6.13

Example 3: Interdepartmental Work Example 3: Interdepartmental Work FlowsFlows

for Assigned Departmentsfor Assigned Departments

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PowerPoint Author’s note: The following three slides are not in the 9e

text, but I like to use them for alternate examples.

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Process Layout - work travels to dedicated process centers

Milling

Assembly& Test Grinding

Drilling Plating

Process LayoutProcess Layout

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Gearcutting

Mill Drill

Lathes

Grind

Heattreat

Assembly

111

333

222

444

222111444

111 3331111 2222

222

3333

111

444111

333333333

44444

3333

3322

222

Functional LayoutFunctional Layout

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-1111 -1111

222222222 - 2222

Ass

emb

ly

3333333333 - 3333

44444444444444 - 4444

Lathe

Lathe

Mill

Mill

Mill

Mill

Drill

Drill

Drill

Heat treat

Heat treat

Heat treat

Gear cut

Gear cut

Grind

Grind

Cellular Manufacturing LayoutCellular Manufacturing Layout

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Video: Process DesignVideo: Process Design

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Video: Process ImplementationVideo: Process Implementation

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Video: Process MappingVideo: Process Mapping