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Process Selection and Facility Layout

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Learning ObjectivesLearning Objectives Explain the strategic importance of process

selection. Describe the basic processing types. 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

Process Selection and Process Selection and System DesignSystem Design

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• Key aspects of process strategy– Capital intensive – equipment/labor– Process flexibility/Adjust to changes

– Design– Volume– Technology

Process StrategyProcess Strategy

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Variety How much

Flexibility What degree

Volume Expected output

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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Product – Process MatrixProduct – Process Matrix

Process TypesProcess Types Job Shop:  It is used when a low volume of high-

variety goods or services will be needed. Processing is intermittent; work includes small jobs, each with somewhat different processing requirements. High flexibility using general-purpose equipment and skilled workers are important characteristics of a job shop. A manufacturing example of a job shop is a tool and die shop that is able to produce one-of-a-kind tools. A service example is a Doctor’s office.

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Process TypesProcess Types Batch:   used when a moderate volume of goods or

services is desired, and it can handle a moderate variety in products or services. The equipment need not be as flexible as in a job shop, but processing is still intermittent.

Manufacturing examples: cakes. Service examples: airline flight, classroom

lectures.

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Process TypesProcess Types Repetitive: used when higher volumes of more

standardized goods or services are needed. The standardized output means only slight flexibility of equipment is needed. Skill of workers is generally low.

Examples of this type of system include production lines and assembly lines. Familiar products made by these systems include automobiles, television sets.

An example of a service system is an automatic carwash. You are likely to see only minor variations in the product or

service being produced using the same process and equipment

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Process TypesProcess Types Continuous.    Used for a very high volume of non-discrete,

highly standardized output. These systems have almost no variety in output and, hence,

no need for equipment flexibility. Workers' skill requirements can range from low to high, depending on the complexity of the system and the expertise workers need. Generally, if equipment is highly specialized, worker skills can be lower.

Examples of non-discrete products made in continuous systems include petroleum products and steel. Continuous services include supplying electricity and water.

Key difference between Repetitive and Continuous is that in Repetitive systems you may experience minor variations in product or service, whereas in Continuous system you will see not almost no variation.

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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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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 Design1. Facilitate attainment of product or service quality2. 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 3

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

Product LayoutProduct Layout

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1 2 3 4

5

6

78910

In

Out

Workers

A U-Shaped Product LineA U-Shaped Product Line

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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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Dept. A

Dept. B Dept. D

Dept. C

Dept. F

Dept. E

Used for Intermittent processingJob Shop or Batch Processes

Process Layout(functional)

Process LayoutProcess 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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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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Service layouts can often be categorized as product, process, or fixed-position layouts.

In a fixed-position service layout (e.g., appliance repair, roofing, home remodeling, copier service), materials, labor, and equipment are brought to the customer's residence or office).

Service LayoutsService Layouts

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Process layouts are common in services due mainly to the high degree of variety in customer processing requirements. Examples include hospitals, supermarkets and department stores, vehicle repair centers, and banks.

Product layout can be used if the service is organized sequentially, with all customers or work following the same or similar sequence, as it is in a car wash.

Service LayoutsService Layouts

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Important factors in service layout design include: Target customer and desired customer experience Customer attitude and image Frequency of orders High level of customer contact The mixture of the physical items, sensual benefits,

and psychological benefits.

Interesting point: service layout design is not generally focused on cost minimization and product flow.

Service Layout DesignService Layout Design

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Line Balancing is the task of deciding how to assign work to specific workstations to achieve maximum utilization of labor and equipment

Design Product Layouts: Line Design Product Layouts: Line BalancingBalancing

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

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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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DOT = timecycle = CT

rateoutput Desired= D

dayper timeoperating OT

CTOT = rateOutput

Determine Maximum OutputDetermine Maximum Output

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• As a general rule, the Cycle Time is determined by the desired output.

• A desired output rate is selected, and the Cycle time is computed.

Cycle TimeCycle Time

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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.

Precedence DiagramPrecedence Diagram

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Example 1: Assembly Line BalancingExample 1: Assembly Line Balancing

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Example 1: Assembly Line BalancingExample 1: Assembly Line Balancing

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Workstation

TimeRemaining Eligible

AssignTask

RevisedTime Remaining

StationIdle Time

1 1.00.90.2

a, ccnone

ac-

0.90.2

0.22 1.0 b b 0.0 0.03 1.0

0.50.3

de-

de-

0.50.3 0.3

Example 1 SolutionExample 1 Solution

Total idle time = 0.2+0.0+0.3 = 0.5

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Percent idle time = Idle time per cycle(N)(CT)

Efficiency = 1 – Percent idle time

Calculate Percent Idle Time & Calculate Percent Idle Time & EfficiencyEfficiency

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Example 2Example 2

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Example 2Example 21. Draw a precedence diagram

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Example 2Example 2

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Example 2Example 2

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Station 1 Station 2 Station 3 Station 4

a b ef

d

g h

c

Example 2Example 2

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Example 2Example 2

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1 min.2 min.1 min.1 min. 60/hr. 60/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

Next session: Quiz # 2 on Next session: Quiz # 2 on Stevenson Ch. 6Stevenson Ch. 6

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