Dr. Tai-Yue Wang IIM Dept. NCKU Introduction Operations Analysis and Improvement 2010 Spring Dr. Tai-Yue Wang Industrial and Information Management Department

Dr. Tai-Yue Wang IIM Dept. NCKU

Introduction

Operations Analysis and Improvement

2010 Spring

Dr. Tai-Yue WangIndustrial and Information Management Department

National Cheng Kung University


Presentation

Throughput or lead time are directly affected by the where and how the processing and storage resources are located in the factory.

Plant layout is an activity that all companies are forced to deal with sooner or later. It is important to be familiar with the

methodologies used to carry out these tasks.


Presentation

Cellular layouts - where labor and machines are grouped in cells - will be explained in depth in the following chapter.


Production Systems Design

HIGH

VARIETY

TRANSFERLINE

SPECIAL SYSTEM FLEXIBLE

MANUFACTURINGSYSTEM

MANUFACTURINGCELLS

STD. AND GEN.MACHINERY

HIGH

LOW

VO

LU

ME

FLEXIBILITY

PRODUCTION CAPACITY


Introduction Factory layout improvements typically occur more than one

time during the factory’s life. The study of plant layouts seeks the optimal location for all of the

production resources. Tries to ensure that the economic impact of the project on the enterprise

will be as positive as possible. New plant layout must be as safe as possible and satisfactory for the

employees.

It seems obvious that the optimal solution will be unreachable or change routinely. Commitment between all the aspects is achieved.


Signs and reasons for a new layout(1/8)

Location change. Reasons to suggest a change of location of the

factory. Location has become inadequate or antiquated. Factory expansion is impossible.



Location change. Layout can be different if the company chooses a

new location by constructing a new building, versus utilizing an existing facility.

New building construction can allow for an ideal layout because building functionality is the principle focus of the building design.

Use of the factory floor space should be better utilized.



Purchase new equipment New needs as well as technology improvements

form the basis of machinery purchase Finding the best location for the purchased equipment

can become a critical issue in making a “system” perform as intended.



Purchase new equipment Newly purchased incremental equipment is

generally placed in free space available. In some cases it is necessary to move machines to create

space. In other cases the new machine is located in a place that

promotes system efficiency.



Equipment set up is typically done once, while the materials flow is a continuing process. The analysis of this material flow can in most

cases be economically formulated.



Problems with materials flow This problem is generally derived from a

problem previously solved. Placing new equipment in available space in the

plant The initial set-up costs decrease, but other problems arise. Materials flow can be adversely affected by introducing

additional equipment.



High work-in-process (WIP). A good policy or layout in a given period of time

may not always produce good results forever. A measure of change in the company is the

amount of partially completed products (work-in-process).

This should not be confused with a temporary situation caused by a momentary increase in demand or stock outages and/or surges.



Slow changes in product variability can hide the negative effects of the excessive work-in-process (WIP).


One-piece flow(1/7) Before we begin exploring

layout analysis tools, it is important to clarify the definition of production and transfer batch even though both sizes are normally the same.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Work

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Vis

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LevelingProductionKanban

Multi-functionalworkers

SMED


One-piece flow(2/7)

Production batch. Number of products included in the

customer order. Transfer batch (unit load).

Amount of units that flows from one machine to the next.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

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JUST IN TIME

Work

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SMED


One-piece flow(3/7)

Work-in-process decreases with a reduction in the transfer batch size.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Work

forc

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Vis

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SMED


One-piece flow(4/7) Advantages of reducing the transfer

batch Production feedback is faster. Lead time decreases.

A reduction in the transfer batch increases the material handling between sections.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Work

forc

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Vis

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SMED


One-piece flow(5/7) The ideal transfer lot size is called

continuous one-piece flow. Normally, a container size is considered

unit load flow. For example, a “1000-screws flow”, can be

used as “unit load flow”.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Work

forc

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Vis

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SMED


One-piece flow(6/7) One-piece-flow eliminates most of the

causes and effects outlined in the previous section. It is one of the Just-in-time tools.

To come closer to an ideal one-piece-flow, the material flow has to be minimized or eliminated. If this is not possible, then the machines

should be located as close together as possible.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

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TPM

JUST IN TIME

Work

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SMED


One-piece flow(7/7)

In order to improve the material flow, it is typically necessary to analyze and change the company’s layout.

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Work

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SMED


Main types of industrial companies

In an open-market, there exists a multitude of different products. food, cars, computers, bricks, cement, ships,...

Each product has a specific manufacturing process.

Analysis is conducted based on similarities Cars and washing machines? yogurt and soap?


Main types of industrial companies

The grouping is based on the type of production facilities that the companies uses. Industrial companies can be grouped into four

sectors. Primary, Secondary, Tertiary and Service Sector.

Secondary Sector (Process Industry and Consumption Industry).

Tertiary Sector (Production and Assembly factories).


Process industry(1/4)

Process focused industries The manufacture of the

product dictates the equipment and product flow.

Paper, wood, cement, painting and fabrics manufacturers,...


Process industry(2/4)

Consumer goods will also be grouped into this type Quality or purity measures will

be much higher. Yogurts, ice creams, drinks,… Pharmaceutical and cleaning

products.


Process industry(3/4) Four main steps

Raw materials preparation Received in bulk and storage in large

warehouses or silos. Product mixing is carried out in

hoppers or in smaller drums. Treatment

filter, dry, separate,...


Process industry(4/4) Finishing

Restore some properties (Metals).

Superficial treatments. Polishing or painting.

Bottling or packaging Bottling or packing lines.


Assembly companies Companies that exclusively

assemble final products. Cars, televisions, microwaves.

Their components are purchased from external companies.


Assembly companies Some processing operations are also

carried out internal to the factory. They are not profitable to subcontract.

Sheet cutting. Welding. Plastic injection molding. Painting.


Manufacturing companies Companies that manufacture

component parts do not belong to any of the previous groups Forges Plastic injection machines Presses CNC machines.


Manufacturing companies Factory layout depends on

the product type and volume to be manufactured Later this will be analyzed in

more detail


Layout types

There are numerous classifications of industry according to their layout.

We will use four basic layout groupings or classifications. The grouping is primarily the result of the material flow in the

production plant Fixed position layout Process layout Product layout Cellular or combination layout


Fixed position layout The product does not move

throughout the production process, the needed resources do. Ships, buildings, trains,… Products with short or immediate needs

Milling center, presses,...

Historically this layout was also used for custom car production


Process layout Machines are grouped into

departments or stations according to the operation that they perform. Presses -> pressing department Lathes -> lathes department


Process layout Used in companies that

manufacture by orders. Specialty parts or components.

A small job shop that makes unique dies or fixtures

Products that are made in very small batches


Process layout. Advantages The flexibility of products (almost

any part that fits within the volumetric boundaries of the machines) is possible.

An in depth understanding of a specific process can be obtained.

Some tooling and fixtures can be shared.


Process layout. Disadvantages The spaghetti flow is

difficult to manage and control.

There is usually a lot of inventory in front of each machine.


Process layout. Disadvantages Set up is usually expensive

and time consuming. Material handling times are

large. It is difficult to automate

these types of systems.


Product layout Machines are grouped according to

the product manufacturing sequence.

These layouts are called manufacturing or assembly lines. High volume component parts are

normally produced using a product layout.


Product layout Assembly companies

normally use this type of layout, especially in the automotive sector.


Product layout The layout change carried out

by Henry Ford drastically reduced the car production lead time. Some companies are able to

manufacture an automobile every 40 seconds.


Product layout. Advantages Large batches can be

produced inexpensively Material handling is minimal In-process materials are

minimized It is easy to control these

systems Automation is more

achievable and justifiable


Product layout. Disadvantages They are inflexible, in that only one or

very few products can be produced on them.

Set-up time for these systems is very large.

Duplicate tooling is required to replace worn tooling so that maintenance can be minimized.


Cellular or combination layouts Some companies can not be

classified exclusively by one of the previous layout types.

Large product manufacturing industries (airplanes or presses) have opted for modularization. Different modules are produced in

different lines and assembled as subsets.


Cellular or combination layouts Dismantling sections and creating

manufacturing cells to accommodate demand. Special screws manufactures. Cellular layout.

Share the critical resource. High cost of the resources.

Combination layout between product and process layouts.


Cellular or combination layouts Common first phase and

different assembly lines to elaborate the final product. Appliances manufactures.

Plastic injection and presses sections, combined with assembly lines grouped by product families.


Fixed positioned Process layout Product layout

ProductDifficult to move or with small and specific demand

Products diversified with variable production volume

Standard products with high production volume

Material flowThe product does not move

Manufacturing particular path (standard routes do not exist)

Unidirectional and the same one for all products

MachineryGeneral machinery and common to all products

Each machine manufactures different products

Specific machinery for each operation

LaborsThe task assignment depends on the project

Specific skill in each process

Repetitive tasks although the rotation of the staff is favored

Characteristic of the traditional layouts


Layout design methodology(1/11)

These next steps are applicable to most of the possible layout problems, they are oriented mainly for a general layout analysis.

Step 1. Formulate the problem. Define what is the main objective of the study.

Including a new machine? Modifying the existing building?



Step 2. Analysis of the problem. Can be carried out in a systematic way.

Richard Muther in his now classic book " Practical Plant Layout " presented 8 factors to consider for facilities layout.

These factors will be described in the tools section.



Step 3. Search for alternatives. The analysis of the 8 Muther’s factors enables engineers to

define the problem and properly align the solution to the problem.

It is important to take into account three practical principles. First the whole and then the details. First the ideal solution and then the practical one. Brainstorming.



Step 3. Search for alternatives. First the whole and then the details.

Giving priority to the general area or total space shared and then to each one of the specific areas.

Layered planes are developed to characterize the situation.



Step 3. Search for alternatives. First the ideal solution and then the practical one.

The ideal solution is difficult to reach. The good solutions can be more easily developed.

A more particle approach is more worthwhile so as not to waste time and effort analyzing this problem in depth.



Step 3. Search for alternatives. Brainstorming.

The “creation of ideas” with not a single solution being rejected. Consider all the ideas without criticizing them.

Being critical at this point can hinder the creativity process. It would not be the first time that, from a seemingly crazy idea, brilliant

solutions are obtained.

It is also important to remember that factories have a third poorly used dimension.

The height or overhead space.



Step 4. Choose the right solution. Choose the solution that fits best among the

solutions that have been proposed in the previous step.

Each one of the solutions should be evaluated according to a specific set of criteria.

Ranking each alternative from 0 to 10 according to the established criteria.



Evaluate each alternative from an economical standpoint.

The simplest solution (between those which have received good ranking) will always be the best choice.



Step 5. Specification of the solution. The accepted solution will need to be

fully developed. Take care of safety measures in order to

avoid possible future industrial accidents.

Occupational Health and Safety Administration (OHSA) regulations and the Labor Risks Prevention Law.



Itemize all details for the plan, budgets and schedule for the implementation of the solution.

Demonstrate quantitatively that the outlined solution will provide benefits when compared to the current situation.



Step 6. Design cycle. Includes planning for modifications that arise due to

problems that appear while adopting a solution. Budget deviations, problems in the plant installations.

At the end of the design process, the plant should work more efficiently.

It is always worthwhile to check to see if the adopted solution works as expected.


Tools for layout study. Muther’s 8 factors

By analyzing the following 8 factors, it is possible to determine the main layout restrictions and requirements. Choose the best layout from a set of proposed

solutions.


Tools for layout study. Muther’s 8 factors

Muther’s 8 factors. Material factor. Machinery factor. Labor factor. Movement factor. Wait factor. Service factor. Building factor. Change factor.


Muther’s 8 factors. Material factor

This factor does not cover the study of the materials that are utilized to manufacture the product.

The purpose of this factor is to become familiar with the different production steps that are needed to manufacture the article. Analyze how the material is transformed from raw

material to a final product. Should be studied without considering the relative

location of each process in the factory.



This factor helps to understand the company technology and to know the company range of products.



The machine types and the existing number of machines on the factory floor. Their principle dimensions in case

this becomes a critical constraint.



Analyze the operating conditions so as to avoid putting incompatible machines together. Vibrations, temperature, etc.

A heavy sheet metal press and a precision coordinate measurement machine are not very compatible.


The staff related with the production department should be counted. Covering machine operators to division heads. Material handling and maintenance operator

input is important.

Muther’s 8 factors. Labor factor


It is recommended to use worker-machine diagrams (a tool that will be explained in a subsequent chapter). Discovery of the operations that the worker

carries out on the machine and the relative disposition of the elements in the working area to simplify the worker tasks.

Muther’s 8 factors. Labor factor


Muther’s 8 factors. Movement factor

Analyzes the materials flow between working centers. This flow does not add value to the product.

As much handling as possible should be eliminated. Completely eliminating movement is an Utopian.

There are mainly two tools to analyze the movement between machines. The flow process chart. Transfer matrix.


Flow process chart. Represents, in a graphic way, the

path and the actions carried out on the product.

Five standard symbols are used. It is possible to combine two or more

of these actions.



Circle -> Operation. Arrow -> Transport. Reversed triangle -> storage. Letter D -> a wait or delay. Square -> Inspection.



Flow process chart. Using these symbols as tools, movement

improvements can be envisaged and advantages quantified.


Number Time (min) Distance (m) Workers

Operation 3 80 - 4

Transport 5 13 102 5

Inspection - - - -

Storage 3 2 - 2

11 95 102 11

Number Time (min) Distance (m) Workers

Operation 4 140 10 5

Transport 7 20 167 7

Inspection - - - -

Storage 3 482 - 2

14 642 177 14

Product 1

Product 2

TOTAL

TOTAL


Transfer matrix A matrix representation of the work flow

Shows the fraction of works that flows from a section to all the others including the RM and FP warehouses.

Considers the total amount of products that enter in a work center

The fraction moving to other work centers is calculated. This is distributed fractionally between the other sections.


M1 M2 M3 M4 M5 W2 M1 M2 M3 M4 M5 W2

W1 0,7 0,2 0,1 W1 0,3 0,2 0,1 0,4M1 0,5 0,3 0,1 0,1 M1 0,3 0,1 0,4 0,2

M2 0,7 0,2 0,1 M2 0,7 0,3M3 0,6 0,2 0,2 M3 0,5 0,1 0,1 0,3M4 0,6 0,4 M4 0,2 0,2 0,6

M5 1 M5 0,1 0,1 0,1 0,6 0,1

TO

FROM

TO

FROM


Transfer matrix. Shows the volume of different products that flows

between working centers. It does not indicate how heavy they are, or the size of

the products.



It is possible to use the same matrix concept but with a different perspective. Factors such as the transferred weight or the number

of routes executed. These matrixes will help to make the decision of the

relative location of the departments in the factory plant



Muther’s 8 factors. Wait factor

This factor covers the study of the three main warehouses Raw materials, work-in-process and final product.

This factor objective is to determine the required space by each one of the warehouses.


Muther’s 8 factors. Wait factor

Due to the magnitude of the warehouse study, a specific layout project must be outlined.

Because the warehouse layout is closely related with its management (planning and control), it will not be studied in this book.


Muther’s 8 factors. Service factor Analyze two different characteristics.

The study of environmental workspace conditions Brightness, noises, smells, minimum working space.

Decide what the acceptable parameters are with respect the OHSA regulations and the Labor Risks Prevention Law.

The working conditions are analyzed, but concerning the plant service staff.

These services are mainly, quality, logistics and maintenance. Minimum maneuver space for the forklift trucks or other

special equipment used.


Muther’s 8 factors. Building and change factors

Building factor. Analyzes the actual useful surface of the building.

The plant shape, the columns, the window situation for ventilation, and areas of possible extension.

The surface area covered by gantry cranes limits the number of layout alternatives.


Muther’s 8 factors. Building and change factors

Change factor. The proposed layout will not be valid forever. The factor intends to observe, from a critical point of

view, the adopted solution. The application of this factor is without a doubt the most

difficult part of the study. Ask for future company plans.


Summary This chapter has demonstrated how material flow

can significantly be improved by means of layout analysis. In this kind of improvement projects, the study of the current situation allows to identify constraints that reduce the number of possible alternatives to be considered. The proposed improvements will reduce the material flow, allowing the company to raise the one-piece-flow proposed by the Lean Manufacturing philosophy.

Documents

Dr. Tai-Yue Wang IIM Dept. NCKU Introduction Operations Analysis and Improvement 2010 Spring Dr. Tai-Yue Wang Industrial and Information Management Department