Layout in operations Management

8/12/2019 Layout in operations Management

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FACILITIES LAYOUT


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The Problem In this lesson, we shall discuss how a plant or

workplace should be laid out.

Consider the problem of finding suitable locations for

machines, workstations, storage areas and aisleswithin a plant.

How to find suitable locations for departments,

lounges and mail rooms and labs within a building

that houses a faculty.

The layout problem may also occur in other places

such as grocery stores, hospitals, airports, etc.


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Objectives of Facility LayoutA facility layout problem may have many objectives. In

the context of manufacturing plants, minimizing material

handling costs is the most common one.

Other objectives include efficient utilization of

space

labor

Eliminate

bottlenecks

waste or redundant movement


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Basic Types of Layouts

Process Layout

Used in a job shop for a low volume, customized

products

Product Layout

Used in a flow shop for a high volume, standard

products


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Fixed position Layout

Lathe Press Grind

Weld AssemblyPaint

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Product Layout

Drill Grind Drill

Lathe

Drill

Drill

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As

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Lathe

Bend

Lathe

Mill

Press

Drill


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Product Layout (cont.) Advantages

1. Since the layout corresponds to the sequence of operations, smooth and logical flow linesresult.

2. Since the work from one process is fed directly into the next, small in-process inventoriesresult.

3. Total production time per unit is short.

4. Since the machines are located so as to minimize distances between consecutive operations,material handling is reduced.

5. Little skill is usually required by operators at the production line; hence, training is simple,short, and inexpensive.

6. Simple production planning control systems are possible.

7. Less space is occupied by work in transit and for temporary storage.

Limitations

1. A breakdown of one machine may lead to a complete stoppage of the line that follows thatmachine.

2. Since the layout is determined by the product, a change in product design may require majoralternations in the layout.

3. The pace of production is determined by the slowest machine.

4. Supervision is general, rather than specialized.

5. Comparatively high investment is required, as identical machines (a few not fully utilized) aresometimes distributed along the line.


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Process Layout

Lathe Drill Weld

Mill

Drill

Grind

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Lathe

Lathe

Mill

Mill

Lathe

Mill

Paint

Grind

Assembly

Assembly

Paint

Weld


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Process Layout (cont.) Advantages

1. Better utilization of machines can result; consequently, fewer machines are required.

2. A high degree of flexibility exists relative to equipment or man power allocation forspecific tasks.

3. Comparatively low investment in machines is required.4. The diversity of tasks offers a more interesting and satisfying occupation for the operator.

5. Specialized supervision is possible.

Limitations

1. Since longer flow lines usually exist, material handling is more expensive.

2. Production planning and control systems are more involved.

3. Total production time is usually longer.4. Comparatively large amounts of in-process inventory result.

5. Space and capital are tied up by work in process.

6. Because of the diversity of the jobs in specialized departments, higher grades of skill arerequired.


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Product vs. Process Layouts

A process layout is a functional grouping of machines.

For example, a group of lathe machines are arranged

in one area, drill machines in another area, grinding

machines in another area and so on. Different jobjumps from one area to another differently. Hence, the

flow of jobs is difficult to perceive. This type of layout is

suitable for a make-to-order or an assemble-to-order

production environment, as in a job shop wherecustomization is high, demand fluctuates, and volume

of production low. Since a wide variety of products are

produced, general purpose equipments and workers

with varied skills are needed.


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A product layout arrangement of machines. Every job

visits the machines in the same order. This type of

layout is suitable for a make-to-stock or an assemble-

to-stock production environment, as in a flow shopwhere products are standard, demand stable, and

volume of production high. Since variety is low, special

purpose equipments and workers with a limited skill are

needed. Advantage

A process layout provides flexibility

A product layout provides efficiency.


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Inventory

A product layout has a low work-in-process

inventory and high finished goods inventory because

production is initiated by demand forecast.

On the other hand, a process layout has a high

work-in-process inventory and low finished goods

inventory.

Material handling

A product layout can use automatic guided vehicles

which travels in a fixed path. But, variable path

forklifts are suitable for a process layout.


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Scheduling

In case of a process layout, jobs arrive throughout

the planning period. A process layout requires

dynamic scheduling where a new scheduling

decisions is made whenever a new job arrives.

In case of a product layout, sequencing and timing

of product flow are standard and set when the line is

designed.


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Every cell contains a group of machines which are

dedicated to the production of a family of parts.

One of the problems is to identify a family parts that

require the same group of machines.

These layouts are also called as group technology

layouts.

Cellular Layouts


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Parts 1 2 3 4 5 6 7 8 9 10 11 12

A x x x x x

B x x x xC x x x

D x x x x x

E x x x

F x x x

G x x x x

H x x x

Machines

Cellular Layouts Example


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Parts 1 2 4 8 10 3 6 9 5 7 11 12

A x x x x x

D x x x x xF x x x

C x x x

G x x x x

B x x x x

E x x x

H x x x

Machines

Cellular Layouts Example


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Advantages of Cellular Layouts

Reduced material handling and transit time

Reduced setup time

Reduced work-in-process inventory

Better use of human resources

Better scheduling, easier to control and automate


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Group Layout

Drill Grind Assembly

Drill

Weld

Assembly

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Lathe

Assembly

Grind

Press

Mill

Lathe

Paint

Drill

Drill

Press

Grind

Assembly


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Group Layout (cont.) Advantages

1. Increased machine utilization.

2. Team attitude and job enlargement tend to occur.

3. Compromise between product layout and process layout, with associated advantages.

4. Supports the use of general purpose equipment.5. Shorter travel distances and smoother flow lines than for process layout.

Limitations

1. General supervision required.

2. Higher skill levels required of employees than for product layout.

3. Compromise between product layout and process layout, with associated limitations.

4. Depends on balanced material flow through the cell; otherwise, buffers and work-in-process storage are required.

5. Lower machine utilization than for process layout.


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Factors that Affect the Flow Pattern

Number of parts in each product

Number of operations on each part

Sequence of operations in each part

Number of subassemblies Number of units to be produced

Desired flexibility


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Flow Pat.: Flow between Departments Flow between departments is a criterion often used to evaluate

flow within a facility.

Flow typically is a combination of the basic horizontal flowpatterns shown below. An important consideration in combiningthe flow patterns is the location of the entrance (receiving

department) and exit (shipping department).

Straight

U flow

Serpentine

L flow

S flow

Circularflow

Simplest. Separate

receiving/shipping

crews

Very popular.

Combine receiving/shipping. Simple to

administer

When line is too long

Similar to straight.

It is not as long.

Terminate flow.Near point of origin


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Flow within a facility considering the locations of

entrance and exit

At the same location

On adjacent sides


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Flow within a facility considering the locations of

entrance and exit (cont.)

On the same side but

at opposite ends

On opposite sides


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Vertical Flow Pattern

Flow between buildings exists

and the connection between

buildings is elevated

Ground level ingress (entry)

and egress (exit) are required

Ground level ingress (entry)

and egress (exit) occur on the

same side of the building

Travel between floors occurs on

the same side of the building

Some bucket and belt

conveyors and escalators result

in inclined flow

Backtracking occurs due to the

return to the top floor


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Flow Planning Planning effective flow involves combining the above patterns with adequate

isles to obtain progressive movements from origin to destination.

An effective flow can be achieved by maximizing directed flow paths, reducingflow, and minimizing the costs of flow.

A directed flow path is an uninterrupted flow path progressing directlyfrom origin to destination: the Figure below illustrates the congestion andundesirable intersections that may occur when flow paths are interrupted .

Uninterrupted flow paths

Interrupted flow paths


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Measuring Flow

1. Flow among departments is one of the most important factors in the arrangement of

departments within a facility.

2. Flows may be specified in a quantitative manner or a qualitative manner.

Quantitative measures may include pieces per hour, moves per day, pounds per week.

Qualitative measures may range from an absolute necessity that two departments show be

close to each other to a preference that two departments not being close to each other.3. In facilities having large volumes of materials, information, a number of people

moving between departments, a quantitative measure of f low will typically be the basis for

the arrangement of departments. On the contrary, in facilities having very little actual

movement of materials, information, and people f lowing between departments, but having

significant communication and organizational interrelation, a qualitative measure of flowwill typically serve as the basis for the arrangement of departments.

4. Most often, a facility will have a need for both quantitative and qualitative measures

of f low and both measures should be used.

5. Quantitative flow measure: From-to Chart

Qualitative flow measure: Relationship (REL) Chart


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Activity Relationship Chart

An activity relationship chart is a graphical tool usedto represent importance of locating pairs ofoperations near each other.

Importance is described using letter codes defined

below:A - absolutely necessary

E - especially important

I - important

O - ordinarily important

U - unimportantX - undesirable


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Production area

Office rooms

Storage

Dock area

Locker room

Tool room

A A

A

O

O

U

O O

U

U

U

U

EX

I

Activity Relationship ChartExample: Its ordinarily

important to locate

office rooms near

loading/unloading area


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Activity Relationship Chart

Sample interpretation of the diagram on theprevious slide:

To find how important it is to locate office

rooms near loading/unloading area, find thediamond shaped block at the intersection ofoffice rooms and loading/unloading area. Theblock contains O meaning ordinarilyimportant. Therefore, its ordinarily important to

locate office rooms near loading/unloadingarea.


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From-To Chart

Punch

Saws Milling Press DrillsSaws 18 40 30

Milling 18 38 75

Punch Press 40 38 22

Drills 30 75 22

A from-to chart is used to analyze flow ofmaterials between departments. The examplebelow shows distances in feet. So, the distance

between Saws and Drills is 30 feet. The chartmay also show material handling trips or costper period.


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Flow Patterns

Store

Turning

Milling

Press

Plate

Assembly

Warehouse

Stores Turning Milling

Warehouse Assembly Plate

Press

Stores Press Plate Assembly

Turning Milling Warehouse

Stores Milling Warehouse

Turning Press Plate Assembly

Straight-line flow U-shaped flow

W-shaped flowS-shaped flow


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Layout in operations Management

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