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Operations Management-14

Process layout

IBS Campus Case

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Layout Planning Decisions about the physical arrangement of economic

activity centres within a facility. An economic activity centre can be anything that takes up

space a person or group of persons, an admissionswindow, a workstation, a cafeteria, a stairway or an elevatorshaft, a storage room, a department, a classroom, the desks

and chairs or whiteboards in a classroom and so on. Layout determines the way in which materials and other

inputs (like people and information) flow through theoperation.

Relatively small changes in the position of a machine in a

factory can affect the flow of materials considerably. Gettingit wrong can lead to inefficiency, inflexibility, large volumesof inventory and work in progress, high costs and unhappycustomers.

Changing a layout can be expensive and difficult, so it is best

to get it right first time.

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Layout Planning: Questions

What centres should the layout include?

The tasks that will be undertaken by each work centre.

How much space and capacity does each centrerequire?

How should each centres space be configured?

Where should each centre be located? Relative location placement of a centre relative to other

centres

Absolute location the particular space that the centreoccupies within the campus.

The degree and direction of flow between each workcentre (for example number of journeys, number ofloads, cost of flow per distance travelled).

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General objectives

Inherent safety. Dangerous processes should not beaccessible without authorisation. Fire exits should beclearly marked with uninhibited access. Pathways shouldbe clearly defined and not cluttered.

Length of flow. The flow of materials and informationshould be channelled by the layout to fit best the objectivesof the operation. This generally means minimising thedistance travelled by materials.

Clarity of flow. All flow of materials should be clearly

signposted, for example using clearly marked routes. Staff comfort. The layout should provide for a well

ventilated, well lit and, where possible, pleasant workingenvironment.

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General objectives

Management coordination. Supervision andcommunication should be assisted by the location ofstaff and communication equipment.

Accessibility. All machines, plant and equipment should

be easily accessible for cleaning and maintenance. Use of space. All layouts should make best use of the

total space available (including height as well as floorspace). This usually means minimising the space for aparticular process.

Long-term flexibility. Layouts need to be changedperiodically. Future needs (such as expansion) shouldbe taken into account when designing the layout.

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Systematic layout planning (SLP)1. Develop a relationship chart (Muther grid) showing the degree of

importance of having each department located adjacent to everyother department.

2. From this chart, an activity relationship diagram depicting materialhandling between departments, is developed.

3. Draw up a schematic layout showing the work centres and the

flow between them, putting the work centres with the greatestflow closest to each other.

4. Adjust the schematic layout to take into account the constraints ofthe area into which the layout must fit.

5. Draw the layout showing the actual work centre areas anddistances that materials must travel. Calculate the effectivenessmeasure of the layout either as total distance travelled or as thecost of movement.

6. This pattern, in turn, is modified department by department tomeet building space limitations.

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80

80

40

73

320

320

160

A

E

D

C

B

Preliminary schematic layout

40

80

80

73

320

320

160

A

ED

C

B

Adjusted schematic layout

This is to be adjusted to fit the building geometry.

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Relationship chart/aeiou

matrix/(Richard) Muther grid

Faculty Chambers (1), Printer/Xerox (2),

Water Coolers (3), Student Restrooms

(4) Classrooms (5), and Library (6)

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Muther grid for Ibs

Xs

Student Rest Rooms(4) not close to Faculty

Chambers(1)

Water Coolers (3) not close to Library(6)

Water Coolers (3) not close to Student Rest

Rooms(4)

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Muther grid for Ibs

As

Faculty Chambers(1) close to Printer/Xerox(2)

Faculty Chambers (1) close to Water

Coolers(3)

Printer/Xerox(2) close to Library(6)

Water Coolers(3) close to Classrooms(5)

Student Rest rooms (4) close to Library(6)

Classrooms (5) close to Library(6)

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Muther grid for Ibs

We create a cluster of links using the

departments rated A beginning with the

department that occurs most frequently

which is 6 as follows

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Muther grid for Ibs Then we take the remaining

departments rated A andadd them to this maincluster using trial and errorto address the closenessrelationships.

If departments do not link to this main cluster we will need to

create a new cluster but in this case all the departments link to

the above cluster.

Similarly we can also graphically depict

the relationship between departments

rated X

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Muther grid for Ibs

Since the cluster of departments rated A also satisifies the

relationship between those rated X, we can assign

departments with inspection as follows. Close can mean

diagonally close too.

Note: In this case all the e,i,o and u ratings are also satisfied

though this is not always necessary.

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Load Distance Analysis

Each department is 10 feet by 10 feet,

distances are rectilinear, which of the

following two layouts is better?

Layout A Layout B

3 8

7 4

1 10

9 2

6 5

4 7

10 1

2 9

5 6

8 3

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Routing/Travel Distances

Product Department

Processing Sequence

Quantity Processed

Per Month

A 1 5 410 1,000 units

B 2 6 3 9 2,000

C 210 1 9 3,000D 1 7 810 1,000

E 2 5 6 9 2,000

F 1 7 410 4,000

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Routing/Travel Distances

Distance Between

Departments (feet)

Distance Between

Departments (feet)

Flow Layout A Layout B Flow Layout A Layout B

1 5 30 30 39 30 201 7 10 10 45 30 30

1 9 10 10 47 10 10

1 10 10 10 410 10 10

2 5 10 10 56 10 102 6 20 20 69 10 10

2 10 10 10 78 20 50

3 6 40 10 810 20 30

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Solution (1/2)

Compute the total travel for each product

through each layout alternative.

Product

Department

Processing

Sequence

Distance per

Product (feet)

Layout A

Distance per

Product (feet)

Layout B (feet)

A 1 5 410 30+30+10= 70 30+30+10= 70

B 2 6 3 9 20+40+30= 90 20+10+10= 50

C 210 1 9 10+10+10= 30 10+10+10= 30

D 1 7 81010+20+20= 50 10+50+30= 90

E 2 5 6 9 10+10+10= 30 10+10+10= 30

F 1 7 410 10+10+10= 30 10+10+10= 30

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Solution (2/2)

Compute total distance traveled per month by

each product through each layout alternative.

Units per Distance per Product Distance per Month

Product Month Layout A Layout B Layout A Layout B

A 1000 70 70 70,000 70,000

B 2000 90 50 180,000 100,000

C 3000 30 30 90,000 90,000

D 1000 50 90 50,000 90,000E 2000 30 30 60,000 60,000

F 4000 30 30 120,000 120,000

Totals 570,000 530,000*

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Registration process: initial layout

Since 900 students have to be processed between 9am 6pm which is 9 hours or 8 hours excluding an hour for lunch

Cycle time = Time Available/Number to be processed = 0.6

(no lunch) or 0.53 minutes Throughput Time = Since every student has to be processed

at each of the stages on average he/she spends 22.4minutes

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Load matrix for current registration

Process

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Distance Matrix

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Cost Matrix

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Load*Distance*Cost Matrix

To A B C D

From

A - 450*30*1 350*60*2 50*90*2

B 350*30*1 - 200*30*1 0

C 0 0 - 750*30*1D 0 0 0 -

To A B C D Total

From

A - 13500 66000 9000 88500

B 10500 - 6000 0 16500

C 0 0 - 22500 22500

D 0 0 0 - 0

Total 127500

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Improving the layout

A more optimal layout would therefore resultfrom moving in the priority order apparent fromthe descending order of travel costs observedabove

i. Departments A and C closer without disturbingthe relative proximity of A and B nor disturbingthe relative proximity of C and D since themovement costs between these departments is

large. ii. Attempting to move departments A and D and

then B and C closer than currently.

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Alternative layout 1

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Alternate Layout-2

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Suppose diagonal movements are to

be treated as non adjacent

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Process or functional Layout Process layouts are sometimes called functional

layouts because the transforming resources with thesame, or similar, function are grouped together.Products with different requirements move betweenthe clusters of transforming resources in differentways.

This makes this kind of layout particularly flexible. Itcan usually cope with a wide variety of differentprocessing requirements.

However, it is complex to manage with flows crossing

each other and moving on irregular and intermittentpaths.

The same is true in office environments. Eachfunctional group sits together in a work area, andsupports multiple product teams.

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Cell layout

Primarily this type of layout is an attempt to

reduce the complexity of process layouts.

It divides transforming resource up into small

clusters which can be used to act upon

different products or product groups.

Within each cell layout can be almost identical

to product layout

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Detailed design of cell layouts

The detailed design of cell layouts is difficult, because cellsare a compromise between process and product layout.

One method is to find which processes naturally grouptogether. This involves examining each process and askingwhich other processes might also be needed for a typical

product. For example, when making furniture, if all partsthat need holes drilling in them also need those holes to becountersunk, then it makes sense to locate drilling andcountersinking machines in the same cell.

Another method is to design the cells around product

families. The families indicate the characteristics of similarproducts, such as size, shape and material that determinetheir processing requirements. Cells can then be designedto co-locate the necessary processes for different productfamilies.

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Production flow analysis

Product families

Machines

1 2 3 4 5 6 7 81 X X2 X X X3 X X X4 X X X5 X X X6 X X7 X X8 X X X

Basic product family and machine data

hi d d f ili

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Machines and product families

reorganised into cellsProduct families

Machines

3 6 8 5 2 4 1 74 X X X

Cell A1 X X6 X X3 X X X

Cell B8 X X2 X X X5

Cell CX X X

7 X XThis analysis rarely results in a totally clean division between cells. In

this case, product family 8 (allocated to cell A) needs processing by

machine 3, which has been allocated to cell B.

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Ways to solve the problem

1. Purchase another machine the same as machine 3 andput it in cell A. This solves the problem but requiresinvesting capital in a new machine that might be underutilised.

2. Send products in family 8 to cell B after they have beenprocessed in cell A. This avoids the need to purchaseanother machine but it results in more complex materialsflow.

3. If there are several product families that have thisproblem, devise a special cell for them including allnecessary machines to tackle their processing needs. Thisinvolves extra capital expenditure, but removes theproblem product families from the rest of the operation,leaving it with a more predictable and ordered flow.

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A u shaped cell is a specific form of work cell designed to

eliminate walking. The operator finishes where he starts, so

there is no time wasted walking back to the first process.