Plant layout

Facility Layout Planning

Introduction.

Objectives of Plant Layout.

Factors affecting Plant Layout.

Types of Plant Layout.

Plant Layout for a Service business.

Plant Layout for a Warehouse.

Facility Layout Planning

Introduction Objectives Factors Affecting Layout Selection and

Design Types of Plant Layout

Product Layout Process Layout Cell Layout

Layout for Services

Introduction Plant layout planning includes decisions regarding the physical

allocation of the economic activity centers in a facility. An economic activity center is any entity occupying space. The objective of plant layout planning is a more effective

work flow at the facility, allowing workers and equipment being more productive.

Facility layout techniques apply to the case where several physical means have to be located in a certain area, either industrial processes or services.

The objective of the chapter is not only Plant layout but re-layout also (most common situation for a company).

To carry out an appropriate plant layout, it’s important to take into account the business strategic and tactical objectives Example: space requirements/cost per m2 in Malls;

accessibility/privacy in offices.

Introduction To make a decision about layout planning, 4 different

questions must have an answer: Which centers do we have to consider? How much space and capacity is required for each center?

If there is not enough space, productivity may be reduced. Too much space is expensive and may also reduce

productivity. How must the space be configured at each center?

Space quantity, shape and the elements of the work center are related to each other.

Where should each center be located at within the facility? The allocation of the different centers may affect productivity.

Introduction The plant layout process starts at an aggregate level, taking into

account the different departments. As soon as we get into the details, the different issues arise, and the original configuration may be changed through a feedback process.

Most (if not all of them) layouts are designed properly for the initial conditions of the business, although as long as the company grows and has to be adapted to internal and external changes, a re-layout is necessary.

Introduction The reasons for a re-layout are based on 3 types of

changes: Changes in production volumes. Changes in processes and technology. Changes in the product.

The frequency of the re-layout will depend on the requirements of the process.

Introduction Symptoms that allow us to detect the need for a re-layout:

Congestion and bad utilization of space. Excessive stock in process at the facility. Long distances in the work flow process. Simultaneous bottle necks and workstations with idle time. Qualified workers carrying out too many simple operations. Labor anxiety and discomfort. Accidents at the facility. Difficulty in controlling operations and personnel.

Lay Out



Product Layout Process Layout

Layout for Services

Facility Layout Definition A facility layout is an arrangement of everything

needed for production of goods or delivery of services. A facility is an entity that facilitates the performance of any job. It may be a machine tool, a work centre, a manufacturing cell, a machine shop, a department, a warehouse, etc. (Heragu, 1997).

ProductLayouts

FixedPositionLayouts

Mixed Layouts Process Layouts

QuantityQuantity

Number of Different ProductsNumber of Different Products

The layout design generally depends on the products variety and the production volumes. Four types of organization are referred to, namely fixed product layout, process layout, product layout and cellular layout (Dilworth, 1996).

Objectives of Plant Layout The main objective consists of organizing equipment

and working areas in the most efficient way, and at the same time satisfactory and safe for the personnel doing the work. Sense of Unity

The feeling of being a unit pursuing the same objective. Minimum Movement of people, material and

resources. Safety

In the movement of materials and personnel work flow. Flexibility

In designing the plant layout taking into account the changes over short and medium terms in the production process and manufacturing volumes.

Objectives of Plant Layout These main objectives are reached through the attainment of the

following facts: Congestion reduction. Elimination of unnecessary occupied areas. Reduction of administrative and indirect work. Improvement on control and supervision. Better adjustment to changing conditions. Better utilization of the workforce, equipment and services. Reduction of material handling activities and stock in process. Reduction on parts and quality risks. Reduction on health risks and increase on workers safety. Moral and workers satisfaction increase. Reduction on delays and manufacturing time, as well as increase

in production capacity. All these factors will not be reached simultaneosly, so the best

solution will be a balance among them.

Factors affecting Plant Layout The final solution for a Plant Layout has to take into account a

balance among the characteristics and considerations of all factors affecting plant layout, in order to get the maximum advantages.

The factors affecting plant layout can be grouped into 8 categories: Materials Machinery Labor Material Handling Waiting Time Auxiliary Services The building Future Changes

Factors affecting Plant Layout The factors affecting plant layout can be grouped into

8 categories: Materials

The layout of the productive equipment will depend on the characteristics of the product to be managed at the facility, as well as the different parts and materials to work on.

Main factors to be considered: size, shape, volume, weight, and the physical-chemical characteristics, since they influence the manufacturing methods and storage and material handling processes.

The sequence and order of the operations will affect plant layout as well, taking into account the variety and quantity to produce.


8 categories: Machinery

Having information about the processes, machinery, tools and necessary equipment, as well as their use and requirements is essential to design a correct layout.

The methods and time studies to improve the processes are closely linked to the plant layout.

Regarding machinery, we have to consider the type, total available for each type, as well as type and quantity of tools and equipment.

It’s essential as well to know about space required, shape, height, weight, quantity and type of workers required, risks for the personnel, requirements of auxiliary services, etc.


8 categories: Labor

Labor has to be organized in the production process (direct labor, supervision and auxiliary services).

Environment considerations: employees’ safety, light conditions, ventilation, temperature, noise, etc.

Process considerations: personnel qualifications, flexibility, number of workers required at a given time as well as the type of work to be performed by them.

Material Handling Material handling does not add value to the product; it’s just

waste. Objective: Minimize material handling as well as combining with

other operations when possible, eliminating unnecessary and costly movements.


8 categories: Labor

Labor has to be organized in the production process (direct labor, supervision and auxiliary services).

Environment considerations: employees’ safety, light conditions, ventilation, temperature, noise, etc.

Process considerations: personnel qualifications, flexibility, number of workers required at a given time as well as the type of work to be performed by them.

Material Handling Material handling does not add value to the product; it’s just

waste. Objective: Minimize material handling as well as combining with

other operations when possible, eliminating unnecessary and costly movements.


8 categories: Waiting time - Stock

Objective: Continuous Material Flow through the facility, avoiding the cost of waiting time and demurrages that happen when the flow stops.

On the other hand, the material waiting to flow through the facility not always represents a cost to avoid. As stock sometimes provides safety to protect production, improving customer service, allowing more economic batches, etc. It’s necessary then to consider space for the required stock at the

facility when designing the layout. Resting time to cool down or heating up…


8 categories: Auxiliary Services

Support the main production activities at the plant: Related to labor: Accessibility paths, fire protection installations,

supervision, safety, etc. Related to material: quality control. Related to machinery: maintenance and electrical and water lines.

The auxiliary services represent around 30% of the space at a facility.

The space dedicated to auxiliary services is usually considered as waste. It’s important to have efficient services to insure that their indirect

costs have been minimized.


8 categories: The building

If it has been already selected, its characteristics will be a constraint at the moment of designing the layout, which is different if the building has to be built.

Future changes One of the main objectives of plant layout is flexibility. It’s important to forecast the future changes to avoid having an

inefficient plant layout in a short term. Flexibility can be reached keeping the original layout as free as

possible regarding fixed characteristics, allowing the adjustment to emergencies and variations of the normal process activities.

Possible future extensions of the facility must be taken into account, as well as the feasibility of production during re-layout.

Types of Plant Layout The production process normally determines the type

of plant layout to be applied to the facility: Fixed position plant layout

Product stays and resources move to it. Product oriented plant layout

Machinery and Materials are placed following the product path.

Process oriented plant layout (Functional Layout). Machinery is placed according to what they do and

materials go to them. Cell Layout

Hybrid Layout that tries to take advantage of different layouts types.

Product Oriented LayOut

CamionesCamiones

Espuela de Ferrocarril

Types of Plant Layout Product oriented plant layout

This type of plant layout is useful when the production process is organized in a continuous or repetitive way. Continuous flow: The correct operations flow is reached through

the layout design and the equipment and machinery specifications.

Repetitive flow (assembly line): The correct operations flow will be based in a line balancing exercise, in order to avoid problems generated by bottle necks.

The plant layout will be based in allocating a machine as close as possible to the next one in line, in the correct sequence to manufacture the product.

Types of Plant Layout Product oriented plant layout

Advantages: Reduced material handling activities. Work In Process almost eliminated. Minimum manufacturing time. Simplification of the production planning and control systems. Tasks simplification.

Disadvantages: No flexibility in the production process. Low flexibility in the manufacturing times. High capital investment. Every workstation is critical to the process.- The lack of

personnel or shut down of a machine stops the whole process. Monotonous work.

a) Flujo en línea recta

b) Flujo en “U”

c) Flujo en serpentín

d) Flujo en “L”

d) Flujo circular ó en “O”

e) Flujo en “S”

Process layout

Espuela de Ferrocarril

CamionesCamiones

RecepciónFresadoras

Almacén Materia Prima

Planeación

MaquinariaAutomática

Tornos

Esmeriladoras

Inspección

Ensamble

Almacén ProductoAcabado

Em

barque

Types of Plant Layout Process oriented plant layout (Functional Layout)

This type of plant layout is useful when the production process is organized in batches.

Personnel and equipment to perform the same function are allocated in the same area.

The different items have to move from one area to another one, according to the sequence of operations previously established.

The variety of products to produce will lead to a diversity of flows through the facility.

The variations in the production volumes from one period to the next one (short periods of time) may lead to modifications in the manufactured quantities as well as the types of products to be produced.

Product Flow

P-Q Analysis

Diagram activity relationships

Chart relationship (flow, functional)

Establish space requirements Space Availability

Diagram space relationships

Practical LimitationsMaintenance

QCMat. Handling

Space Availability

Project Project ProjectA B C

Evaluate alternative arrangements

Detail selected layout, install

INSTALACION

Definition

Analysis

Synthesis

Evaluation

Selection

Implementation

Adjustment

SLP MethodMuther (1973)

Cellular Layout

Process (Functional) Layout

Process (Functional) Layout Group (Cellular) LayoutGroup (Cellular) Layout

Similar resources placed together

Resources to produce similar products placed together

T T T

MM M T

M

SG CG CG

SG

D D D

D

T T T CG CG

T T T SG SG

M M D D D

M M D D D

A cluster or cell

Types of Plant Layout Work cells

Definition: Group of equipment and workers that perform a sequence of

operations over multiple units of an item or family of items. Looks for the advantages of product and process

layouts: Product oriented layout: Efficiency Process oriented layout: Flexibility

Group Technology Grouping outputs with the same characteristics to families, and

assigning groups of machines and workers for the production of each family.

Lay Out




Layout for Services

Plant Layout for a Service Business Most of the concepts and techniques explained here

can be applied to any plant layout, including services. Examples: Line Balancing for Restaurant self-services;

Process oriented layout for Hospitals. Service Businesses have a more direct customer

focus: Sometimes, the customer is required at the facility for the

company to be able to perform the service. Frequently, the layout is focused on the customer satisfaction

than on the operation itself. Some of the objectives include comfortability during the

performance of the service, as well as making attractive those areas in direct contact with the customer.

Plant Layout for a Service Business Service Businesses have a more direct customer

focus: The customer, with his/her presence, creates the work flow.

The workload forecast and the activities planning is not as accurate as it is in a manufacturing environment.

Queues: Seasonal and heterogeneous demand: execution time can be

variable. Services are intangible: adjustment between demand and production

can not be done through inventory management. Queues are formed by people: higher implications for the layout.

Plant Layout for a Service Business Plant layout for an office:

The material that flows among departments and workstations is basically information. This can be done through: Individual conversations face to face. Individual conversations through telephone or computer. Mail and other physical documents. Electronic mail. Meetings and discussion groups. Interphones.

The layout solution is dictated by workers and physical documentation movements.

Plant Layout for a Service Business Plant layout for a commerce:

Objective: Maximize the net benefit per m2 of shelves. If sales are directly related to the exposition of products to the

customer, the objective will consist of exposing as many products as possible to the customers in the available space. This has to take into account to leave enough space for the

movement among shelves, not making the layout uncomfortable for the customer.

Aspects: Allocation of daily consumption products at the periphery.-

Allocation of impulsive purchase and high profit margin products in prominent places.

Eliminate aisles that allow the customers to go from one row to other without going through them completely.

Plant Layout for a Service Business Plant layout for a commerce:

Aspects: Global organization of the available space:

Allocation of attraction products on both sides of a row, and dispersion of them to increase the exposition of adjacent products.

Use the end of a row as a place for exposition. Creation of the business image through a careful selection of the first

section where the customers are getting into the facility.

Allocation of products in the exposition areas: This aspect remains within the commercial function. It is called

merchandising.

Cafetería

Cafetería

Three Retail Layout Patterns Grid

Rectangular with parallel aisles; formal; controls traffic flow; uses selling space efficiently.

Free-Form Free-flowing; informal;

creates "friendly" environment; flexible.

Boutique Divides store into a series

of individual shopping areas, each with its own theme; unique shopping environment.

Plant Layout for a Warehouse Objective: Optimal relationship between space and material handling costs.

Aspects to be considered: cubic space utilization, storing equipment and methods, material protection, allocation of different parts, etc.

A warehouse layout is more complicated when: The different customer orders take into account a high number of references. There are frequent orders of low number of units for the same product.

In this cases, the material handling costs for each roundtrip move would be excessively high.

Solutions for this problem: Aggregation of units for several orders, or establishment of optimal routes for each order.

Click to add titleZones Zones Control

station Shipping doors

Tractor trailer

Tractor trailer

Overflow

Feeder lines

Feeder lines

Lay Out




Layout for Services

Systematic Layout Planning

Product Flow

P-Q Analysis

Diagram activity relationships

Chart relationship (flow, functional)

Establish space requirements Space Availability

Diagram space relationships

Practical LimitationsMaintenance

QCMat. Handling

Space Availability

Project Project ProjectA B C

Evaluate alternative arrangements

Detail selected layout, install

INSTALACION

Definition

Analysis

Synthesis

Evaluation

Selection

Implementation

Adjustment

SLP MethodMuther (1973)

Types of Plant Layout Process oriented plant layout

It’s essential to design a flexible plant layout, taking into account as well the need of flexibility for the material handling equipment to be used.

Main disadvantage of this layout: Low operations and material handling efficiency when

comparing to a plant layout oriented to the product. On the other hand, technology development is facilitating

getting over this disadvantage (i.e.- CNC Equipment). Analysis

Decision to be made: Relative location of the different working areas (same type of equipment).

Criteria: reduction of distance and material handling costs: Increase of operations efficiency.


Analysis If it exists a clear material flow that carries out more volume

than anyone else, the layout could be similar to a Product oriented plant layout.

The main factor for the analysis is the material handling and transportation costs among the different working areas.

Sometimes, quantitative information relative to material handling flows is not available, or it’s not the main factor to be considered, being the qualitative factors the most important ones in this case.


Analysis Process:

Information gathering. Plan development. Quantitative criteria: transportation costs. Qualitative criteria: closeness priorities.

Information gathering We have to know the space requirements by working area.

Demand forecast – production plan – working hours – number of workers and equipment.

Consider demand and production fluctuations.


Analysis Information gathering

Working area space. Static area (Se): Physical space for equipment and

workstations. Gravitation area (Sg): Allocation of tools and materials.

Area where operators develop their work. Evolution area (Sv): Space to allow operators and

material movements.

St=Se+Sg+Sv

Sg=Se*n Sv=(Se+Sg)*k

n=number of accessible sides k=industry coefficient (0,05-3)



Available space. Total available area at the plant. Divide the area at a first approach to estimate each

section. When performing the detailed layout, it’s required to have

more accurate shapes adjusted to the reality. When the objective is the reduction of material handling

costs, we can solve the problem in quantitative terms: It’s required to know the material flow among departments

or areas, distances among them and means of transportation.



When the objective is the reduction of material handling costs, we can solve the problem in quantitative terms: Traffic intensity matrix: Number of material handling

moves among departments (information provided by historical data, route sheets and production plans).

Distance matrix: Distances among areas at the plant and places where the different working areas could be allocated.

Cost matrix: Cost of material transportation.- It depends on the type of equipment to be used.



Sometimes, quantitative information is not available, or the importance of distance among areas depends on qualitative factors (i.e.- a hospital X-ray room may be close to the trauma medicine room).

Plan development Once the size of the different areas have been determined,

the next step is to organize the different areas within the existent facility, or to determine the desired shape for the facility construction.

There are multiple possible solutions, so the selected one will be the a good one that complies with the max. number of constraints.

P-Q Analysis

ProductLayouts

FixedPositionLayouts Mixed Layouts Process Layouts

QuantityQuantity

Number of Different ProductsNumber of Different Products

WAREHOUSE

DIRTY EMPTY BOTTLES

UNCASER

WASHER

QC

EBI MANUAL SIGHTING

FILLER/ CROWNER

PASTEURIZER

COMPLEMENTARY ACTIVITIES

BI-DIRCTIONAL TABLE

FGI MANUAL SIGHTING

COMPLEMENARY ACTIVITIES

LABELLER

LABELLER

PACKER

PACKER

PALLETIZER

MANUAL PACKING

WAREHOUSE DISTRIBUTOR CUSTOMERS


Analysis Quantitative criteria: Transportation costs.

With the information gathered in the previous 3 matrixes, the objective is to minimize the transportation costs.

Total Transportation Cost:

Objective: Finding the combination of dij that minimizes TTC. This formula is complicated for common cases, due to the

number of different possibilities (i.e.- for 10 sections, the alternatives would be 3,628,000).

TTC= ΣΣ tij dij cij



Use of heuristics: Algorithm of basic transposition Initial arbitrary layout: base permutation. Transportation cost calculation for this layout. Generation of all possible permutations among activities,

interchanging the ones in the initial arbitrary layout 2 to 2:

Transportation cost calculation for each of the generated permutations: If we get one with a lower cost than the base, this last one becomes the base permutation and the process starts again until there is no one with a lower cost.

Number of permutations =(n*(n-1))/2



In practice, we have to take into account certain constraints and circumstances that have to be considered, apart from the quantitative criteria of the transportation costs.

Once this information is taken into account, the next step will be to perform the spatial design of the different departments.


Analysis Qualitative criteria: Closeness priorities.

Technique: Systematic Layout Planning (SLP) Closeness priorities have a letter code:



Technique: Systematic Layout Planning (SLP): Example.




S1

S6S5S4

S3S2

Initial Diagram




S1

S4S6S5

S2S3

First iteration




S3

S5S6S2

S1S4

Second iteration (might be the optimum)


Detailed layout Equipment and machinery layout within each area or

department, getting a detailed layout of installations and all elements.

There could appear some issues like scales, elevators, columns, floor resistance, roof height, etc. not considered in previous stages, that could make necessary the review of the solution.

Cellular Layout


Definition: Group of equipment and workers that perform a sequence of

operations over multiple units of an item or family of items. Looks for the advantages of product and process

layouts: Product oriented layout: Efficiency Process oriented layout: Flexibility

Applies the principles of Groups’ Technology to Manufacturing: Grouping outputs with the same characteristics to families, and

assigning groups of machines and workers for the production of each family.


Applies the principles of Groups’ Technology to Manufacturing: Sometimes, these outputs will be final products or services;

some other times, they will need to integrate to a final product. In this case, the work cells would need to be located close to the

main production line, to facilitate the assembly of the component at the moment and place required.

Real Work Cells: the grouping of workers and equipment is a fact: At the same time as identifying family of products and grouping of

equipment, it’s essential to perform an internal layout of the cell (by product, by process or a combination of both…generally by product).


Applies the principles of Groups’ Technology to Manufacturing: Virtual Work Cells: identifying and dedicating certain equipment

to the production of certain families of outputs, but without grouping them physically within the cell: The only issue is the identification of equipment and families of

products, without performing an internal layout of the cell. Residual Work Cells: only used when there is a specific item that

has not been associated to any family, or a specialized equipment can not be included within a work cell due to its general use.

Advantages: lower production cost and better supply and customer service time.


Applies the principles of Groups’ Technology to Manufacturing: Steps to follow:

Select product families. Determine work cells. Detail the work cells’ internal organization or layout.

Regarding product grouping to be produced at the same work cell, we need to determine which is the condition that allows such grouping.

Once product families are determined, creating a work cell for each family might be the best solution, although is not always like that (sometimes it’s even impossible).


Applies the principles of Groups’ Technology to Manufacturing: Approaches used to identify families and work cells:

Classification and codification of all items to be manufactured, and comparison among them to define families. After that, it’s required to identify the cells and equipment to manufactured those families.

Creation of work cells by grouping of equipment. In this case, we still need to define the families.

Definition of families by similar manufacturing routes. Still pending the cells’ identification.

Simultaneous identification of families and cells, based on the similarity of products and their needs of equipment and vice versa.


Applies the principles of Groups’ Technology to Manufacturing: A component that does not use all machines within its work cell

can be accepted, as well as a machine that does not process all components in its group.

However, it’s essential to avoid that a component or machine interacts with other machine or component outside of its cell. If it’s not possible avoid this situation, the solution will be duplicating

the piece of equipment, or process the item in more than one cell.- Sometimes a residual cell might be needed to absorb a component like this or to include a general type of equipment that we can not duplicate.


Applies the principles of Groups’ Technology to Manufacturing: In general, the steps to follow to reorganize the layout will be:

Incompatible equipment must be located in separate cells. Each component should be produced only in 1 cell. Each type of equipment should be located only in 1 cell. Investment in duplicating equipment should be minimized. The work cell should be limited to a reasonable size.

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Plant layout