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Chapter 6. Process Selection and Facility Layout. Learning Objectives. You should be able to: Explain the strategic importance of process selection Describe the influence that process selection has on the organization Compare the basic processing types

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Chapter 6

Chapter 6

Process Selection

and Facility Layout


Learning objectives

Learning Objectives

  • You should be able to:

    • Explain the strategic importance of process selection

    • Describe the influence that process selection has on the organization

    • Compare the basic processing types

    • Describe the basic layout types, and the main advantages and disadvantages of each

    • Solve simple line-balancing problems

    • Develop simple process layouts

Instructor Slides


Process selection

Process Selection


Process selection1

Process Selection

  • Process selection

    • Deciding on the way production of goods or services will be organized

    • Occurs when:

      • Planning of new products or services

      • Technological changes in product or equipment

      • Competitive pressure

6-4


Process selection2

Process Selection

Process choice is demand driven:

  • Variety

    • How much?

  • Equipment flexibility

    • To what degree?

  • Volume

    • Expected output?

6-5


Process selection3

Process Selection

  • Goal:

    • Have process capabilities match product/service requirements.

  • Major implications:

    • Capacity planning

    • Layout of facilities

    • Equipment

    • Design of work systems

6-6


Process selection and system design

Facilities andEquipment

CapacityPlanning

Forecasting

Layout

Product andService Design

ProcessSelection

WorkDesign

TechnologicalChange

Process Selection and System Design

6-7


Process types

Process Types

  • Job shop

    • Small scale, intermittent

    • e.g., doctor, tailor, veterinarian

  • Batch

    • Moderate volume

    • e.g., bakery, cinema, airline

  • Repetitive/assembly line

    • High volumes of standardized goods or services

    • e.g., automobiles

  • Continuous

    • Very high volumes of non-discrete goods

    • e.g., petroleum products, steel, sugar, salt, electricity, Internet

  • Project (leave it to later chapter)

    • Non-routine, with a unique set of objectives to be accomplished in a limited time frame

    • e.g., consulting, launching a new product, publishing a book, building a bridge


Types of processing

Types of Processing

  • Goal:

    • Have process capabilities match product/service requirements.

6-9


Product process matrix

Product-Process Matrix

Variety

Volume

  • The diagonal represents the “ideal” match

  • Hybrid process are possible (e.g., job-shop & batch)

  • Process choice may change as products goes through its life-cycles

6-10


Process choice effects

Process Choice Effects

6-11


Product and service profiling

Product and Service Profiling

  • Product or service profiling

    • Linking key product or service requirements to process capabilities

    • Key dimensions relate to

      • Range of products or services that will be processed

      • Expected order sizes

      • Pricing strategies

      • Expected frequency of schedule changes

      • Order-winning requirements

6-12


Product and service profiling1

Product and Service Profiling


Facilities layout

Facilities Layout


Facilities layout1

Facilities Layout

  • Layout

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

    • Facilities layout decisions arise when:

      • Designing new facilities

      • Re-designing existing facilities

6-15


The need for layout planning

The Need for Layout Planning

  • Inefficient operations

    • High cost

    • Bottlenecks

  • Accidents or safety hazards

  • Changes in product or service design

  • Introduction of new products or services

  • Changes in output volume or product mix

  • Changes in methods or equipment

  • Changes in environmental or other legal requirements

  • Morale problems

6-16


Layout design objectives

Layout Design Objectives

  • Basic Objective

    • Facilitate a smooth flow of work, material, and information through the system

  • Supporting objectives:

    • Facilitate product or service quality

    • Use workers and space efficiently

    • Avoid bottlenecks

    • Minimize material handling costs

    • Eliminate unnecessary movement of workers or material

    • Minimize production time or customer service time

    • Safety

6-17


Importance of layout decisions

Importance of Layout Decisions

  • Requires substantial investments of money and effort

  • Involves long-term commitments

  • Has significant impact on cost and efficiency of short-term operations


Basic layout types

Basic Layout Types

  • 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

  • Combination layouts


Repetitive processing product layout repetitive and continuous processes

Repetitive Processing: Product Layout (repetitive and continuous processes)


Product layouts

Product Layouts

  • Product layout

    • Layout that uses standardized processing operations to achieve smooth, rapid, high-volume flow

    • http://www.youtube.com/watch?v=uVoQJrz0sH8

Raw materials

or customer

Station

2

Station

3

Station

4

Finished item

Station

1

Material

and/or labor

Material

and/or labor

Material

and/or labor

Material

and/or labor

Used for Repetitive Processing

Repetitive or Continuous

6-21


A u shaped production line

1

2

3

4

In

5

Workers

6

Out

10

9

8

7

A U-Shaped Production Line


Bottleneck operation

Bottleneck Operation

An operation in a sequence of operations whose capacity is lower than that of the other operations

Bottleneck

10/hr

(6 min/unit)

Operation 120/hr

(3 min/unit)

Operation 210/hr

(6 min/unit)

Operation 315/hr

(4 min/unit)

Maximum output ratelimited by bottleneck

5-23


Line balancing

Line Balancing

  • Line balancing

    • The process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements

    • Goal:

      • Obtain task grouping that represent approximately equal time requirements:

        • minimizes idle time along the line

        • results in a high utilization of equipment and labor

    • Input

      • Tasks sequencing (precedence diagram)

      • Tasks time

      • Operating time

6-24


Real world case

Real-World Case

Instructor Slides


Precedence diagram

Precedence Diagram

  • Precedence diagram

    • A diagram that shows elemental tasks and their precedence requirements

6-26


Cycle time

Cycle Time

  • Cycle time

    • The maximum time allowed at each workstation to complete its set of tasks on a unit

      • Minimum Cycle Time = longest task time = 1.0 min

      • Maximum Cycle Time = Σt = sum of task time = 2.5 min

6-27


Desired output rate

Desired Output Rate

  • Establishing the desired output rate of a line:

6-28


How many workstations are needed

How Many Workstations are Needed?

  • The required number of workstations is a function of:

    • Desired output rate

    • The ability to combine tasks into a workstation

  • (theoretical) Minimum number of stations

6-29


Assigning tasks to workstations

Assigning Tasks to Workstations

  • Some Heuristic (Intuitive) Rules:

    • 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.

6-30


Example 1 assembly line balancing

Example 1: Assembly Line Balancing

  • Arrange tasks shown the figure into workstations.

    - Assign tasks in order of the most number of followers


Determine the minimum number of workstations required

Determine the Minimum Number of Workstations Required

Assume:

OT (Operations Time per Day)=8 hours=8*60=480 minutes

D (Desired output rate)=480 units

CT (Cycle Time)=OT/D=480/480=1.0 minutes per unit


Example 1 solution

Example 1 Solution

Assign tasks in order of the most number of followers


Example 1 solution1

Example 1 Solution

Assign tasks in order of the most number of followers


Example 1 solution2

Example 1 Solution


Example 1 solution3

Example 1 Solution


Example 1 solution4

Example 1 Solution


Example 1 solution5

Example 1 Solution


Example 1 solution6

Example 1 Solution


Example 1 solution7

Example 1 Solution


Example 1 solution8

Example 1 Solution


Example 1 solution9

Example 1 Solution


Example 1 solution10

Example 1 Solution

Idle time per cycle=0.5


Example layout

Example - Layout

a & c

(0.1+0.7)

b

(1.0)

d & e

(0.5+0.2)


Measuring effectiveness

Measuring Effectiveness

  • Balance delay (percentage of idle time)

    • Percentage of idle time of a line

  • Efficiency

    • Percentage of busy time of a line

6-45


Example measuring effectiveness

Example - Measuring Effectiveness

Efficiency = (1– 0.167)x100=83.3%

6-46


Product layouts1

Product Layouts

Advantages

  • High rate of output

  • Low unit cost

  • Labor specialization

  • Low material handling cost per unit

  • High utilization of labor and equipment

  • Established routing and scheduling

  • Routine accounting, purchasing, and inventory control

Disadvantages

  • Creates dull, repetitive jobs

  • Poorly skilled workers may not maintain equipment or quality of output

  • Fairly inflexible to changes in volume or product or process design

  • Highly susceptible to shutdowns

  • Preventive maintenance, capacity for quick repair and spare-parts inventories are necessary expenses

  • Individual incentive plans are impractical

6-47


Non repetitive processing process layout job shop and batch processes

Non-repetitive Processing: Process Layout (Job Shop and Batch Processes)


Process layouts

Process Layouts

  • Process layouts (Non-repetitive Processing)

    • Layouts that can handle varied processing requirements

Dept. A

Dept. C

Dept. E

Dept. B

Dept. D

Dept. F

Used for Intermittent processing

Job Shop or Batch

6-49


Information requirements

Information Requirements

  • In designing process layouts, the following information is required:

    • A list of departments to be arranged and their dimensions

    • A projection of future work flows between the pairs of work centers

    • The distance between locations and the cost per unit of distance to move loads between them

    • The amount of money to be invested in the layout

    • A list of any special considerations

    • The location of key utilities, access and exit points, etc.

6-50


Designing process layouts

Designing Process Layouts

  • The main issue in designing process layouts concerns the relative placement of the departments

  • Measuring effectiveness

    • A major objective in designing process layouts is (trying) to minimize:

      • Transportation cost

      • Distance

      • Time

6-51


Designing process layouts minimize transportation costs

A

B

C

Designing Process LayoutsMinimize Transportation Costs

  • Heuristic:

    • Assign departments with the greatest interdepartmental work flow first to locations that are closet to each other.

  • Goal:

    • Assign departments 1, 2, 3 to locations A, B, C in a way that minimizes transportation costs.

6-52


Example minimize transportation costs

C

A

B

Example: Minimize Transportation Costs

40

Distance

30

closest

20

Place dept. 1&3

in A&B

Work flow

Highest work flow

6-53


Chapter 6

30

170

100

1

2

3

C

A

A

B

B

C

Example: Minimize Transportation Costs

40

  • Place departments 1&3 in A&B

  • 2&3 have higher work flow than 1&2 (100>30)

    • 2&3 should be located closer than 1&2

    • B closer to C than to A (30<40)

  • Solution:

30

20

6-54


Closeness ratings relationship diagramming

Closeness Ratings(Relationship Diagramming)

  • Allows the considerations of multiple qualitative criteria.

  • Input from management or subjective analysis.

  • Indicates the relative importance of each combination of department pairs.

Muther’s grid


Closeness ratings

Production

Offices

Stockroom

Shipping and receiving

Locker room

Toolroom

Closeness Ratings

A Absolutely necessary

E Very important

I Important

O Ordinary importance

U Unimportant

X Undesirable

O

A

U

I

E

O

A

A

X

U

U

U

O

O

O


Closeness ratings example

Dept. 1

Dept 2.

Dept 3.

Dept 4.

Dept. 5

Dept 6.

Closeness Ratings : Example

A

A

E

X

U

U

X

O

I

A

A

O

X

A

A

Assign department using the heuristic:

Assign critical departments first (they are most important)


Closeness ratings example1

Dept. 1

Dept 2.

Dept 3.

Dept 4.

Dept. 5

Dept 6.

Closeness Ratings : Example

1. List critical departments (either A or X):

A

A

E

X

U

U

X

O

I

A

A

O

X

A

A


Closeness ratings example2

Dept. 1

Dept 2.

Dept 3.

Dept 4.

Dept. 5

Dept 6.

Closeness Ratings : Example

2. Form a cluster of A links (beginning with the department that appears most frequently)

A

A

E

X

4

U

U

2

6

X

O

I

A

A

5

O

X

A

3. Take the remaining A links in order and add them to this cluster where possible (rearranging as necessary)

Form separate clusters for departments that do not link with the main cluster.

A

4

2

6

1

5

3


Closeness ratings example3

Dept. 1

Dept 2.

Dept 3.

Dept 4.

Dept. 5

Dept 6.

Closeness Ratings : Example

4. Graphically portray the X links

1

A

4

A

3

E

X

6

U

U

X

O

I

A

A

5. Adjust A cluster as necessary.

O

X

A

A

4

(in this case, the A cluster also satisfies the X cluster).

2

6

1

5

3


Closeness ratings example4

Dept. 1

Dept 2.

Dept 3.

Dept 4.

Dept. 5

Dept 6.

Closeness Ratings : Example

4

2

6

1

5

A

1

3

4

A

3

E

X

6

U

U

X

O

I

  • 6. Fit cluster into arrangement (e.g., 2x3)

    may require some trial and error.

    Departments are considered close not only when they touch side to side but also when they touch corner to corner.

A

A

O

X

A

A

7. Check for possible improvements


Process layouts1

Process Layouts

Advantages

  • Can handle a variety of processing requirements

  • Not particularly vulnerable to equipment failures

  • General-purpose equipment is often less costly and easier and less costly to maintain

  • It is possible to use individual incentive systems

Disadvantages

  • In-process inventories can be high

  • Routing and scheduling pose continual challenges

  • Equipment utilization rates are low

  • Material handling is slow and inefficient

  • Complicates supervision

  • Special attention necessary for each product or customer

  • Accounting, inventory control, and purchasing are more complex

6-62


Fixed position layouts

Fixed Position Layouts

  • Fixed Position layout

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

Ship

Dam

6-63


Combination layouts

Combination Layouts

  • Some operational environments use a combination of the three basic layout types:

    • Hospitals

      • process + fixed

    • Supermarket

      • process + product

  • Some organizations are moving away from process layouts in an effort to capture the benefits of product layouts

    • Cellular manufacturing

    • Flexible manufacturing systems

6-64


Service layout

Service Layout

  • Service layouts can be categorized as:

    • product

    • process

    • fixed position

  • Other common service layouts:

    • Warehouse and storage layouts (easy access to items in high demand)

    • Retail layouts (influence sales, customer attitude, customer flow, avoid customer confusion)

    • Office layouts

6-65


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