Facilities Layout

FACILITIES LAYOUT•Basic Layout Types

•Designing product Layouts

FACILITIES LAYOUT

– refers to the configuration of departments, work centers, and equipment, with particular emphasis on movement of work through the system.

Common reasons for redesigning layouts are:

• Inefficient operations• Accidents or safety hazards• Changes in the design of products or services• The introduction of new products or services• Changes in the volume of output or of mix outputs• Changes in methods or equipment• Changes in environmental or legal requirements• Morale problems

Factors in Determining Layout

Ease of future expansion or flow of movement

Materials handling Output needs Space utilization Ease of communication and support Impact on employee morale and job

satisfaction Promotional value Safety

Objectives of a Good Layout

- To provide enough production capacity- To reduce the cost of material handling- To minimize the accidents and hazards to

personnel- To reduce the congestion and to utilize the

space efficiently and effectively

Objectives of a Good Layout

- To utilize labor efficiently and to improve the morale of the employees

- To achieve easy supervision- To make maintenance process easier - To achieve high degree of

machine/equipment utilization- To improve productivity.

Basic Layout Types

•Product Layout•Process Layout

•Fixed-Position Layout

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

Job is divided into a series of standardized tasks, permitting specialization of both labor and equipment.

1. Product Layouts

Achieve a high degree of labor and equipment utilization which tends to offset their high equipment cost

Only one or few very similar items are involved.

1. Product Layouts

Production Lines – Standardized layout arranged according to a fixed sequence of production tasks.

Assembly Lines – Standardized layout arranged to a fixed sequence of assembly tasks.

Assumptions:

Volume is adequate for high equipment utilization.

Product demand is stable enough to justify high investment in specialized equipment.

Assumptions: Product is standardized or

approaching a phase of its life cycle that justifies investment in specialized equipment.

Supplies or raw materials and components are adequate and of uniform quality to ensure that they will work with the specialized equipment.

Advantages of Product Layouts

a) High rate of outputb) Low unit cost due to high volume; high

cost of specialized equipment is spread over many units.

c) Labor specialization that reduces training costs and time, and results in a wide span of supervision.


c) Low material-handling cost per unit; material handling is simplified because units follow the same sequence of operations.

d) A high utilization of labor and equipment


e) Routing and Scheduling encompassed in the initial design of the system; they do not require much attention once system is operating.

f) Accounting, purchasing, and inventory control is fairly routine.

Disadvantages of Product Layouts

a) The intensive division of labor usually creates dull, repetitive jobs that provide little opportunity for advancement and may lead to morale problems

b) Poorly skilled workers may exhibit little interest in maintaining equipment or in the quality of output.


c) The system is fairly inflexible in response to changes in the volume of output or changes in product or process design.

d) The system is highly susceptible to shutdown caused by equipment breakdowns or excessive absenteeism.


e) Preventive maintenance, the capacity for quick repairs, and spare-parts inventories are necessary expenses.

f) Incentive plans tied to individual output are impractical since they would tend to cause variations among outputs of individual workers.

U-Shaped Layouts

More compact than straight production line; requires approximately half the length of straight production line.

Permits increased communication among workers on the line because workers are clustered

U-Shaped Layouts

Flexibility in work assignments is increased because workers can handle not only adjacent stations but also opposite sides of the line

Minimizes material handling because materials enter the plant at the same point that finished products leave it.

U-Shaped Layouts

Process Layouts

Layouts that can handle varied processing requirements

Common in non-manufacturing environments; e.g. hospitals, colleges and universities, banks, repair shops, airlines.

Process Layouts

Arrange equipments by type rather than by processing sequence

General-purpose machines provide flexibility necessary to handle a wide range of processing requirements which are operated by skilled workers.

Process Layouts Feature departments or other functional

groupings in which similar activities are performed; e.g. machine shop process layout which has separate departments for milling, grinding, drilling, and so on.

Advantages of Process Layouts

a) System can handle a variety of processing requirements.

b) The system is not particularly vulnerable to equipment failures.

Advantages of Process Layouts

c) General-purpose equipment is often less costly than the specialized equipment used in product layouts and is easier and less costly to maintain.

d) It is possible to use individual incentive systems.

Disadvantages of Process Layouts

a) In-process inventory costs can be high if batch processing is used in manufacturing systems.

b) Routing and scheduling pose continual challenges.

c) Equipment utilization rates are low.


d) Material handling cost is slow and inefficient, and more costly per unit than under product layouts.

e) Job complexities often reduce the span of supervision and result in higher supervisory cost than with product layouts.


f) Special attention necessary for each product or customer and low volumes result in higher unit costs than with product layouts.

g) Accounting, inventory control, and purchasing are much more involved than under product layouts.

Fixed-position Layouts

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


The nature of the product dictates this kind of arrangement: weight, size, bulk, or some other factor makes it undesirable or extremely difficult to move the product.


Used in large construction projects (buildings, power plants, dams), shipbuilding, and production of large aircraft or space mission rockets.


Focused on timing of material and equipment deliveries so as not to clog up the work site; to avoid relocating materials and equipment around the work site.


Due to many diverse activities carried out on the project, wide range of skills is required, special efforts are needed to coordinate workers, and the span of control can be quite narrow thus administrative burden is much higher.

Other Layout Types

OFFICE LAYOUT:

Its main distinction of office layouts is the importance placed on the flow of information.

RETAIL LAYOUT:

Main objective is to maximize profit through product exposure.

It allocates shelf space and responds to customer behavior.

Five useful ideas for determining the overall arrangement of many stores:1. Locate the high-draw items around

the periphery of the store.

2. Use prominent locations for high-impulse and high-margin items such as house wares, beauty aids, and shampoos.

Five useful ideas for determining the overall arrangement of many stores:3. Distribute what are known in the

trade as “power items”4. Use end-aisle locations because they

have a very high exposure rate.5. Convey a mission of the store by

carefully selecting the position of the lead-off department.

Three elements to provide good service layout

Ambient conditions Spatial layout and functionality Signs, symbols, and artifacts

WAREHOUSING AND STORAGE LAYOUT Addresses trade-offs between space and

material handling. Management’s task is to maximize the

utilization of the total “cube” of the warehouse to utilize its full volume while maintaining low material handling costs and all the costs related to the transaction.

Random stocking

Used in warehousing to locate stock wherever there is an open location.

-Random stocking systems can increase facility utilization and decrease labor cost, but require accurate records.

Automated Identification systems (IASs)

-Usually in the form of barcodes, allow accurate and rapid item identification, operations manager know the quantity and location of every unit.

Computerized random stocking system includes the following tasks:

Maintaining a list of “open” locations. Maintaining accurate records of

existing inventory and its locations. Sequencing items on orders to

minimize the travel time required to “pick” orders.

Computerized random stocking system includes the following tasks:

Combining orders to reduce picking time.

Assigning certain items or classes of items, such as high-usage items, to particular warehouse areas so that the total distance traveled within the warehouse is minimized.

WORK-CELL LAYOUT

Arranges machinery and equipment to focus on production of a single product or group of related products.

WORK-CELL LAYOUT

Machines are grouped into what is referred to as a cell which is determined by the operations needed to perform work for a set of similar items that require similar processes.

WORK-CELL LAYOUT

Machines are arranged to handle all of the operations necessary for a group of similar parts thus all parts follow the same route although minor variations are possible.

Advantages of work cells:

Reduced work-in-process inventory Less floor space Reduced raw material and finished

goods inventories Reduced direct labor cost

Advantages of work cells:

Heightened sense of employee participation

Increased use of equipment and machinery

Reduced investment in machinery and equipment

Requirements of Work Cells

Identification of families of products, often through the use of group technology codes or equivalents.

A high level of training and flexibility Either staff support or flexible, imaginative

employees to establish work cells initially. Test at each station into the cell.

Designing Product Layouts

(Line Balancing)

Line Balancing

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

Line Balancing

The goal of line balancing is to obtain task groupings that represent approximately equal time requirements which minimizes the idle time along the line and results in a high utilization of labor and equipment.

Process of Line Balancing1) Identify the cycle time and determine the

minimum number of workstations.

Cycle Time (CT) – The maximum time allowed at each workstation to complete its set of tasks on a unit. It also establishes the output rate of a particular line.

Where: OT = Operating Time per dayCT = Cycle Time

Cycle Time may be determined by dividing the Operating Time per day (OT) by the Desired output rate (D):

The minimum number of workstations (Nmin) may be computed as follows.

Where:Nmin = Theoretical minimum number of

stationsD = Desired output rateOT = Operating time per workstation

= Sum of task times

2) Make assignments to workstations in order; beginning with station 1. Tasks are assigned to workstations moving from left to right through the precedence diagram.

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.

Precedence Diagram – A tool used in line balancing to display element task and system requirements. It is read from left to right wherein the initial tasks are on the left and the final task is on the right.

3) Before each assignment, use the following criteria to determine which tasks are eligible to be assigned to workstation.

a. All preceding tasks in the sequence have been assigned.

b. The task time does not exceed the time remaining at the workstation.

4) After each task assignment, determine the time remaining at the current workstation by subtracting the sum of times for task already assigned to it from the cycle time.

5) Break ties that occur using one of the rules.

a. Assign the task with the longest task time.

b. Assign the task with the greatest number of followers

If there is still a tie, choose one task arbitrary.

6) Continue until all tasks have been assigned to workstations.

7) Compute appropriate measures (e.g., percent idle time, efficiency) for the set of assignments.

ExampleA manager wants to assign workstations in such

a manner that hourly output is 4 units. Working time is 56 minutes per hour. What is the cycle time?

What is the positional weight for each task?A= 3+2+4+9+5 = 23 E = 4+9+5 = 18B= 2+4+9+5 = 20 F = 5+6+4+9+5 = 29C= 9+5 + 4 =18 G= 6 + 4 + 9 + 5 = 24D= 7+4+9+5 = 25 H = 9+5 = 14

Numbers above the circles indicate task times (minutes)

Cycle time = operating time/output rate= 14 mins.

Nmin = (4 units per hour X 45mins) / 56 minutes per hour= 3.21 (round to 4)

Assign the tasks above to workstations in the order of greatest positional weight.

TaskPositio

nal Weight

F 29

D 25

G 24

A 23

B 20

C 18

E 18

H 14

I 5

19.64%100%*(4)(14)

11 = time idle Percent

Idle Time per Cycle = 2 + 3+ 6= 11 minutes

Efficiency = 100% - 19.64%= 80.36 %

Activity:A shop wants an hourly output of 33.5

units per hour. The working time is 60 minutes per hour. Assign the tasks using the rules:a) In the order of greatest positional

weight.

Activity:

unitper minutes hourper units

hourper minutes

output Desired

time Operating80.1

5.33

60CT

Task Number of following tasks

Positional Weight

A 7 6B 6 4.6C 2 1.6D 2 2.2E 2 2.3F 1 1.0G 1 1.5H 0 0.5

Nmin = (33.5 units per hour X 6 mins) / 60 mins per hour= 3.35 (round to 4)

Work Station

Task Task Time Time Remaining

Feasible tasks

RemainingI A 1.4 0.4 –II B 0.5 1.3 C, D, E

E 0.8 0.5 –III D 0.7 1.1 C

C 0.6 0.5 FF 0.5 0 –

IV G 1.0 0.8 HH 0.5 0.3 –

Efficiency = 100% - 16.67%= 83.33 %

16.67%100%*(4)(1.8)

1.2 = Time Idle Percent

Marks of a Good Layout for Manufacturing and Back-Office Operations

Straight line flow pattern Backtracking kept to a minimum Production time predictable Little inter stage storage of materials Open plant floors so everyone can see

what’s happening

Marks of a Good Layout for Manufacturing and Back-Office Operations

Bottleneck operations under control Workstations close together Orderly handling and storage of materials No unnecessary re-handling of materials Easily adjustable to changing conditions

Marks of a Good Layout for Face to Face Services

Easily understood service flow pattern Adequate waiting facilities Easy communication with customers Easily maintained customer surveillance Clear exit and entry points with adequate

checkout capabilities

Marks of a Good Layout for Face to Face Services Department and processes arranged so that

customers see only what you want them to see

Balance between waiting areas and service areas

Minimum walking and material movement Lack of clutter High sales volume per square foot of facility

References / Credits:

Production / Operations Management (Fifth Edition)

By William J. Stevenson

MGMT302Chapter_06.ppt

By Sarah Hough

7699063-Introduction-of-Line-Balancing.doc

By ro’an

http://www.optimaldesign.com/Download/OptiLine/FalkenauerPLM05.pdf

http://www.acsco.com/LineBalancing.htm http://www.manufacturinginstitute.co.uk/text.asp?PageId=83 http://www.simcore.fr/Pages/en/en_soft_pplb.php?Langue=en

&IndexMnu=6




http://www.acsco.com/LineBalancing.htm



http://www.manufacturinginstitute.co.uk/text.asp?PageId=83

http://www.simcore.fr/Pages/en/en_soft_pplb.php?Langue=en&IndexMnu=6

http://www.simcore.fr/Pages/en/en_soft_pplb.php?Langue=en&IndexMnu=6

Facilities Layout

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