APPLICATION OF LEAN

MANUFACTURING IN

AEROSPACE INDUSTRY

Sreejith S (2014H142141P)

Guided by: Dr. R.P.Mishra

ABSTRACT

Lean manufacturing has shaped

automotive sector’s success in

improving performance along with

reducing costs. Global aerospace

manufacturing has resulted in a

direct need for the development of

new manufacturing techniques and

machines. These emerging

technologies require a specific

approach to technology, supplier and

enterprise communication

development. The aim of this project

is to bring lean principles and apply

lean tools to aerospace

manufacturing sector. The objectives

that are meant to be achieved by this

study are: 1) Study the features of

lean manufacturing and identify the

current state of art in implementing

the same in aerospace sector. 2)

Identify the current requirements

needed in becoming lean. 3)

Develop a model for applying lean

into an aerospace company. For this

a lean model is developed for a

company producing jet engines.

The aerospace companies are

different from automobile

companies and are lagging behind

the latter in implementation of lean

manufacturing. But their distinct

characteristics may become fruitful

for the easier application of lean

tools. In this project it will also be

analysed that if the structure of the

company has got any advantage or

disadvantage over the

implementation.

INTRODUCTION

According to Womack et al. (1990),

the car industry is often referred to

as the `industry of industries’

because of its economic importance

and high levels of innovation. Lean

manufacturing originated in the

automotive sector and the pursuit of

Lean is still common within it.

Aerospace industry is a value-added

and technology integrated industry.

The aerospace manufacturing

suppliers have to coordinate the

demand of quality, delivery, cost

and flexibility of aircraft to achieve

customer satisfaction. Since "The

Machine That Changed the World"

was released, the concept of lean has

attracted attention of a growing

number of experts and scholars from

all over the world. Many researches

were done in different areas.

Aerospace companies too have

recognized that it is an opportunity

to eliminate a lot of waste, and

improve the competitiveness of

companies.

Aerospace industry and automotive

industries are related in some

manner. There are many differences

too. But the transfer of lean

technology is possible to aerospace

also. Womack himself has described

the inter-industrial transfer of lean

production as:

“....the adoption of Lean production,

as it inevitably spreads beyond the

auto industry, will change

everything in almost every

industry—choices for consumers,

the nature of work, the fortune of

companies, and, ultimately, the fate

of nations (Womack et al., 1990:p.

12)”

and

“...we believe, Lean production

will supplant both mass production

and the remaining outposts of craft

production in all areas of industrial

endeavour to become the standard

global production system of the

twenty-first century (Womack et al.,

1990, p. 278).”

The Lean Advancement Initiative

(LAI) at MIT (Massachusetts

Institute of Technology) has studied

Lean for many years with its

participator. They focus on

transforming the company or

enterprise to become Lean by

applying lean thinking and tools

(Lean Advancement Initiative,

2010). The goal of lean is to

eliminate waste from the production

cycle and add customer value.

The examples of Lean

implementation were obvious in the

United States and UK. In the United

States, implementation of lean

programs were first done in

F – 16, F – 22 fighter development

under the support of Lean Aerospace

Initiative (Ronald, 2003). In the UK,

BAE Systems military aircraft

factory had also been actively

involved in Lean activities in the

past (Tyson & Ralph, 2009).

Mainstream manufacturers like

Boeing, Airbus etc are shifting from

their conventional production

system to lean manufacturing.

Though most of the trials like those

of F-22 were not so successful,

Boeing has already advanced ahead

of others and has successfully

transformed their traditional

‘parking lot’ like factory into a

moving line.

GENERAL STRUCTURE| OF

AEROSPACE INDUSTRY

The aircraft industry covers the

scope of civil aircraft, military

aircraft and aircraft

maintenance…etc. It follows a

pyramidal structure. The main

aerospace manufacturing

companies (Tier-1) keep the high

value-added and technical-

intensive activities in house, such

as design, final assembly, flying

tests and marketing…etc. and

offload the low value-added and

labor-intensive production

activities to aerospace

manufacturing suppliers (Tier-2,

Tier-3…), such as detail part

fabrication and aero-structure

assembly…etc. The global

supply chain is then constructed

and organized.

Fig 1. Structure of aerospace industry

Aerospace industry and automotive

industry are related in some manner

which can be noted down as

• Both industries have similar

structure including prime

contractors, sub contractors etc.

• Some companies work in both

areas like Rolls Royce.

• Both industries face similar

challenges towards saturation.

• There is an enormous amount of

technology transfer between

these two industries.

The differences between these

industries can be

• Automotive industry has high

volume setting and the aerospace

industry has a low volume

environment.

• Unit price and life span are

higher for aircrafts.

• Customers for aircraft industries

are generally airliners or

Government.

• Acquisition decisions.

• Contracts are tighter and time

bound.

Both products, aircraft and

automobiles, are becoming more

expensive to produce, more

technologically advanced, and

increasingly complex to

manufacture. At the same time these

products cost more, customers

believe they can afford to pay less.

Both employ highly trained

engineers, traditionally organized

along functional lines such as

landing gear or hydraulic systems in

an aerospace company (or brakes

and drive train in the automobile

industry), who are responsible for

the design in their particular

specialty.

But these differences can be strength

to implement lean in this sector.

• The lower volumes - closer to the

lean idea of single piece flow.

• Already ‘builds to order’ - only

producing aircraft that are

required by their commercial and

military customers.

Lean manufacturing techniques and

procedures which have already

demonstrated improved quality,

increased flexibility and reduced

costs in the automotive industry

could be a source of similar benefits

if implemented in the aerospace

industry.

Changing the role of the

subcontractors and major suppliers

should yield the same results in

aerospace companies as in lean

manufacturing automobile

companies. By incorporating

concerns of the subcontractors early

in the design process, the major

airframers will not only have better

defined specifications and interface

control documents, but when

changes are required they will have

a much better understanding of their

cost, schedule, and performance

impact. This in turn will lead to a

less expenses and higher quality

product. Just-In-Time delivery

techniques, impossible with

traditional supplier relationships,

could be implemented if

subcontractors and airframers work

more closely together, further

cutting costs by reducing expensive

inventory.

A JET ENGINE ASSEMBLY FIRM

A jet engine assembly firm which

falls into tier 2 supplier of main

industry is selected for lean

implementation. The present process

at the industry is understood first.

Then scope for application of lean

was searched. The present system

utilises vertical assembly of a parts

which utilises an elevated platform. It involves manually combining

various sub assemblies built in a

vertical position from the aft end

forward. Various sub assemblies are

brought together to a single place

and joined together. Technicians

move to the place where work is

done.

The main problems associated with

this were identified as:

• Excess inventory.

• Time loss due to unnecessary

motion, delay, transportation etc.

• Flow time not correlated to

customer demand.

• Production status of factory not

visible.

• Poor ergonomics .

• Poor traceability.

• Centre of gravity aspect.

• Detecting errors like irregular

torque values after assembly.

Fig 2. Iris like platform for

assembly in vertical direction.

Fig 3. Assembly operation.

Fig 4. Assembly

A Value Stream Mapping of current

state and analysis is done initially.

From the analysis different wastes

and areas for improvement was

found out. An innovative idea of

horizontal assembly of jet engine is

created. It was found that such a

transfer would allow us to efficiently

use various lean tools like 5s,

Kanban, Poka-Yoke etc. to the line.

Fig 5. Current state VSM

The current state value stream shows

that there is a lot amount of mudas

like motion, conveyance, delay,

inventory etc. that can eliminated.

For this a JIT system is proposed.

Avoiding a central store in the

assembly area, use of line side stores

is suggested. Kanban is used for

withdrawal of parts and tools. This

would reduce the excess inventory

stored and also conveyance. Since

the suppliers to the assembly area

are located well nearer this would be

a logical suggestion. The

conversion into horizontal line

would reduce unnecessary motion

and conveyance mudas and would

introduce better ergonomics. Poka-

Yoke system for fool proofing while

turbine assembly is necessary as it

accounts for most of the disassembly

processes. Now torque is set by

human workers only. Continuous

workload and fatigue may cause

errors. Hence an automated system

for setting the torque and checking

the placement of bolts are proposed.

Creation of a pulse system is

proposed so that the product is

pulled downstream. Also

redistribution of workers along the

line is proposed in view of

horizontal system. This would

stabilize the process and cycle time.

At current state the lead time for

assembly process is found to be 36

hours. Support areas next to each

individual assembly areas are

proposed for introducing Andon

system. With the proposed

improvements the lead time is

expected to reduce to 24 hours.

Improvement in lead time reduction

=

The future state value stream is

plotted as in figure 6.

Fig 6. Future state VSM

The improvements found in future

state VSM can be summed up as:

• Upto 30-40 % flow time

reduction.

• Introduction of JIT reduces the

storage space required.

• Reduced mudas in the form of

transportation, motion and delay.

• No built up WIP inventory.

• Improved flexibility.

• Improved ergonomics.

• Improved Mistake proofing and

Traceability.

• Able to consider and correct

centre of gravity aspects.

This analysis shows the potential of

lean application in jet engine

assembly. Because of the inherent

differences between the industries it

may not be possible to follow all the

lean practices in automotive industry

as itself. But improvisations in

current processes open up a lot of

opportunity for the application of

several lean tools.

CONCLUSION

The lean manufacturing techniques

can be successfully implemented in

aerospace sector. In the aerospace

industry shrinking orders and intense

competition can be successfully met

by lean production to some extent.

Because of the extreme complexity

of aircraft, the interdependence of

the many subsystems, and the higher

skill and education levels of the

aerospace worker, the benefits may

be even greater.

An important issue lying behind is

the control of government and the

laws and policies that directly affect

this area which is time dependent.

The contracts are more time bound

with heavy losses incurred if not met

in proper time. Shifting to lean

production gives more control over

production time and can adjust with

varying demands and norms with

time.

In the proposed model jet engine

assembly all the details like time for

various processes and some

processing steps are not readily

available due to the nature of the

industry itself. With detailed datas

obtained directly from the industry

the improvements might be more

than those in the proposed model.

REFERENCES

• Hsien-Ming Chang, Chikong

Huang, and Chau-Chen Torng,

“Lean Production Implement

Model for Aerospace

Manufacturing Suppliers,”

International Journal of

Innovation, Management and

Technology, Vol. 4, No. 2, 248-

252, April 2013.

• Penny-Anne Cullen1, Bob

Butcher2, Richard Hickman3,

John Keast4, Miguel Valadez,

“The Application Of Lean

Principles To In-Service Support:

A Comparison Between

Construction And The Aerospace

And Defence Sectors”, Lean

Construction Journal, Vol. 2,

No.1,87-104, April 2005.

• Cheryl Adamscheck and Robin

Mcbride, “Road map to the

future”, Boeing Frontiers Online,

Volume 04, Issue 7, November

2005 .

• Jeffrey Amos, “ Transformation

to Agility”, Garland Publishing,

Inc.

• Cynthia L. Segersten, Lieutenant

Colonel, USAF, “CAN LEAN

MANUFACTURING CHANGE

THE AEROSPACE DEFENSE

INDUSTRY ?” MAXWELL AIR

FORCE BASE, ALABAMA

,April 1994.

• A Gunasekarana, E Tirtiroglua, V

Wolstencroft, “An investigation

into the application of agile

manufacturing in an aerospace

company” ,Technovation,

Volume 22, Issue 7, July 2002,

Pages 405–415.

• A.P. Puvanasvaran, C.Z. Mei,

V.A. Alagendran ,”Overall

Equipment Efficiency

Improvement Using Time Study

in an Aerospace Industry”,

Procedia Engineering 68 ( 2013 )

271 – 277.

• Websites of Boeing, Rolls Royce

,Pratt & Whitney, Lean Flight

Initiative etc.