PROCESS SELECTION:Cellular Layouts, Facilities Layouts, Importance of Layout Decisions

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Production and Operations Management MGT613

Lesson 20

In our last lecture, we identified Facilities layout as the configuration of departments, sections, work

centers, equipment with focus being on movement of goods or services or works. So whether it's a

traveler making use of the railway platform, or bus station or airport, or an automobile or a product

during its production stage or a patient needing medical attention, they all would qualify as good

examples of work being moved through a facility. Often poor design of productive system can result in

poor design of the facilities layout. We discussed product, process and hybrid layouts, we now focus our

attention on cellular production. In cellular manufacturing, production work stations and equipment are

arranged in a sequence that supports a smooth flow of materials and components through the production

process with minimal transport or delay. Implementation of this lean method often represents the first

major shift in production activity, and it is the key enabler of increased production velocity and

flexibility, as well as the reduction of capital requirements. The concept of lean production and Just in

Time Production Systems would be studied in detail when we will discuss improvement of Productive

Systems.

Cellular Layouts

Cellular production techniques reflect a relatively new concept in manufacturing and have yet found

immediate acceptance in Pakistani manufacturing industry as well. Organizations which opt for cellular

manufacturing follow the lean production strategy. There are two important concepts to understand at

the moment, what cellular production is and what group technology is? We will discuss lean production

systems in detail towards the end of our semester later, for the time being we can consider lean

production systems as systems which focus on high quality process with elimination of waste and

effective use of available resources.

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 production always would represent the layout of machines while group technology would

reflect the collection of items or products which need the same manufacturing requirements. Both these

terms greatly influence the improvements of process and operations for any organization.

It is pertinent to understand the advantage of cellular layouts over the functional layouts. We already

know that functional layouts are not only conventional in nature but also require more space as well as

somewhat rigid layout plans, with increased special workforce and continuous supervision. The table

below represents the same concept.

Production and Operations Management MGT613

Primary Differences between Functional and Cellular Layouts

Dimension

Functional

Cellular

Number of moves between departments

many

few

Travel distances

longer

shorter

Travel paths

variable

fixed

Job waiting times

greater

shorter

Throughput time

higher

lower

Amount of work in process

higher

lower

Supervision difficulty

higher

lower

Scheduling complexity

higher

lower

Equipment utilization

lower

Higher

Facilities Layouts

We have so far discussed what product and process based layouts are, in between we also focused our

attention on hybrid configuration as well as cellular production layouts. We can thus safely define

facilities layout as the configuration of departments, work centers and equipment, with particular

emphasis on movement of work (customers or materials) through the system.

We come across different layouts in our daily lives especially with respect to the services side. Some

important Service Layouts, which we should know include

Warehouse and storage layouts

Retail layouts

Office layouts

People often confuse retail stores with warehouse stores, an effective way to understand the importance

of these important business channels is to identify the layouts associated with it. Retail configurations

are human friendly and allow the movement of goods through small trolleys for the customers and if

placement of goods in the aisle is to be carried out then simple forklifts or small vehicles are used,

sometimes over head cranes or hoists are also used.

Another important point of difference being the way the goods are displayed and shelved. The layouts

are properly illuminated and ventilated and mostly maintained at a human comfort temperature through

effective heating and air-conditioning. The floors too are mostly vinyled and designed to make the

customer movement less stressful. The movement of goods involves light loads and easy transportation,

as against this the warehouse and storage layouts, which require heavy loads and transportation. These

goods require heavy vehicles and loaders for movement. The stores have different illumination

arrangement then retail outlets. The security measures are different for both types of layouts, ranging

from close circuit television cameras to electric barbed wires.

Importance of Layout Decisions

Operations Managers are often questioned about the importance of a new or existing facilities layout. In

addition to the fact that operations manager work for improvement towards design and effect use of

operation systems, they should also know the importance of layout decision in terms of money. Some of

these are:-

Production and Operations Management MGT613

1. Layout decisions require substantial investments of money and effort.

2. Layout decisions involve long-term commitments.

3. Layout decisions have significant impact on cost and efficiency of short-term operations.

The Need for Layout Decisions

An operations manager should be aware of the fact that the need for a proper and effective layout

facility is always there, it is often said that if there is no facilities layout problem being faced by an

organization then it is probably unaware of its true potential. The need for layout planning arises both in

the process of designing new facilities and in

Redesigning existing facilities. Some of the common reasons faced by the organization include:-

1. In-efficient Operations (High Cost/Bottlenecks that hamper true potential).

2. Accidents or Safety Hazards.

3. Changes in design of products or services.

4. Introduction of new products or services.

5. Changes in volume of output or mix of outputs.

6. Changes in Methods or equipment.

7. Changes in Environmental and Legal requirements.

8. Morale Problems ( e.g. lack of face to face contact between supervisor and worker or even

senior management and junior management).

Design Product Layouts: Line Balancing

Line Balancing is the process of assigning tasks to workstations in such a way that the workstations

have approximately equal time requirements.

The objective of line balancing is to obtain equal time requirements at majority of the workstations. This

shortens the time of manufacturing as well as reduces the idle time. Often industry uses the term cycle

time to represent the time in which the organizations resources are engaged to complete a process and

idle time to represent the time in which the resources are left unused.

Cycle Time

Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit. If CT

represents cycle time and D represents the desired output then we can calculate cycle time as

CT = cycle time =

Maximum Output

If we know what is the cycle time required for the manufacturing of a product or offering of a service

we can calculate the maximum output. If OC is the Output capacity, OT is the operating Time and CT is

the Cycle time then

OC = Output

capacity

If an automobile manufacturer works for 8 hours and requires 4 hours to complete its cycle then the out

put capacity would be 8/4= 2 automobiles.

Minimum Number of Workstations Required

Organizations working especially service organizations side often design their work facilities in a way

that they can increase their capacity output by increasing the number of work stations. If D is the desired

output, t is the time required for a specific time and OT is the Operating Time then the number of

workstations N can be calculated as .

Production and Operations Management MGT613

(D)(∑ t)

∑ t = sum of task times

Precedence Diagram

Precedence diagram: Tool used in line balancing to display elemental tasks and sequence requirements

0.1

1.0

A Simple Precedence

Diagram

0.7

0.5 min.

0.2

Line Balancing 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.

Designing Process Layouts require certain information, which includes the following:

1. List of departments

2. Projection of work flows

3. Distance between locations

4. Amount of money to be invested

5. List of special considerations

6. Location of key utilities

Summary

Facilities layout plays an important part in an organization achieving its maximum potential. This also

indicates that facilities layout allow an organization to enjoy a competitive advantage over its

competitors. Facilities layout require more than just cost benefit analysis infact the decision requires

how much space is required by the facility and how to configure or optimize the use of this space for the

product or process. Of the different types of product, process, fixed and hybrid types of configurations,

the current trend is towards cellular manufacturing and group technology.

Capital investments, materials handling costs and flexibility are important

criteria in judging most facilities layout. Low volumes of production do allow the use of Group

Technology or cellular manufacturing. Designing a process layout requires collecting information about

acceptable block plan, and translating the block plan into a detailed layout. In product layout,

workstations are arranged in a naturally occurring, heuristic (commonsense) for high volume of

production. In line balancing the tasks are assigned to workstations so as to satisfy all precedence and

cycle time constraints while minimizing the number of work stations.

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