-
Virtual verification of an aircraft Final Assembly Line
industrialization: an industrial case
Jos Luis Menndez1,a, Fernando Mas1,b, Javier Servn1,c, Jos
Ros2,d 1AIRBUS Military, Av. Garca Morato s/n, 41011, Sevilla,
Spain
2Universidad Politcnica de Madrid, Jos Gutirrez Abascal 2, 28006
Madrid, Spain, [email protected],
[email protected],
[email protected],
[email protected]
Keywords: Digital Factory and Manufacturing, Assembly Line,
industrial Digital Mock Up (iDMU)
Abstract. This communication describes the experience gained
when implementing a Digital
Manufacturing methodology to validate the industrial design of
the AIRBUS A400M Final
Assembly Line using commercial Product Lifecycle Management
tools. The implementation project
generated a remarkable innovation in the industrialization
methods and tools used in AIRBUS
Military, contributing to the A400M program success. The
document presents: the background and
reasons motivating the project, the context, the main barriers
identified and the definition of a Final
Assembly Line (FAL). An innovative concept of industrial Digital
Mock-Up (iDMU) was coined,
representing the interoperable grouping of product, processes
and manufacturing resources data.
Introduction
The design of the Final Assembly Line (FAL) for an aircraft is a
large and complex project that
involves different companies and departments. The work
environment is characterized by team
work and concurrency and it involves both Product Design and
Industrial Design. Digital
Manufacturing, supported by Product Lifecycle Management (PLM)
software tools, helps to
succeed in designing a FAL. Literature shows some of the
possible general benefits obtained when
implementing Digital Manufacturing concepts [1, 2]. The
simulation of manufacturing systems
using tools based on discrete events is well documented in
literature. References related to aircraft
manufacturing simulation can be found [3, 4]. However, the
concept of Digital Manufacturing by
using PLM tools goes beyond discrete event simulation and
embraces the use of a set of tools,
allowing interoperability and concurrency between product design
and industrial design, to design
products, processes and resources. Few references are found
dealing with the industrial
implementation of Digital Manufacturing in the aerospace
industry [5-7].
In addition to the technical challenges of deploying Digital
Manufacturing tools in a large project
involving several companies and departments, the implementation
of Digital Manufacturing affects
working methods and personnel. A new aircraft project provides
the perfect opportunity to improve
current work methods and tools. This document describes the
experience of applying Digital
Manufacturing in the Industrial Design of the AIRBUS A400M
FAL.
Digital Manufacturing deployment context
The A400M final assembly requirements were quite different from
any prior project. The main
factors were: aircraft size, assembly line rate and FAL concept.
The A400M was quite larger than
all the military transport planes manufactured before. The A400M
production rate of 3 aircraft per
month doubled any prior rate. The FAL concept was also new. For
smaller military transports, the
usual FAL concept integrates the aircraft structure and then
installs the systems. In the A400M
FAL, the main assemblies delivered to the FAL have most of the
systems installed. This implies
that the A400M FAL stations must integrate the structure and
interface and complete the systems.
The Digital Manufacturing project was limited to the FAL
Industrial Design. The FAL Industrial
Design is conducted in concurrency with Product Design. The
process comprises three main stages:
Conceptual Phase, Development Phase and Deployment Phase [8].
The project focused on the
-
Development Phase. The main reason for this decision resided in
the state of the Digital
Manufacturing software tools. The Conceptual Phase deals mainly
with the assembly line layout
and the technologies to be used. Such phase relies mostly in
engineers skill and judgment and the development of Knowledge Based
Engineering tools is subject of research [8, 9]. The Deployment
Phase deals mainly with documenting the processes in detail and
delivering the information needed
to execute the assembly tasks. The shop floor documentation is
the subject of research in applying
augmented reality techniques [10].
Another important factor was on the product design side.
Concurrent Engineering methodology
and practices were implemented in AIRBUS [11], where designs
were issued by a single
organization. In the case of the A400M, designs were made by
several teams from different
organizations and this made the whole concurrency process more
demanding.
Regarding the personnel, AIRBUS Military had already a vast
experience on the design and
deployment of aircraft FALs. However, regarding the use of PLM
tools, there was an imbalance
between product design personnel and industrial design
personnel.
Digital Manufacturing project barriers
The identification of possible barriers to the Digital
Manufacturing deployment allowed anticipating
possible issues and the definition of actions to avoid them.
The first issue arose in the software tools, both PLM and CAD
tools used by the A400M
industrial partners were different. The integration of different
software applications is an industrial
and research issue well document in literature. Interoperability
entangled the aircraft design and it
was an obstacle to implement Digital Manufacturing. The solution
adopted was to promote the
harmonization of a common set of PLM and CAD tools among all the
partners.
Another issue was the application of the Concurrent Engineering
practices. Harmonizing Product
Design and Industrial Design, having different departments and
companies involved, required a new
approach. A validation process for the Industrial Design was
defined and synchronized with Product
Design. A feedback procedure from Industrial Design to Product
Design was defined to incorporate
industrialization considerations into the aircraft design and
optimize its industrialization.
The different level of PLM and CAD tools implementation between
AIRBUS Military and
providers was also an issue. The aircraft design was carried out
in-house using PLM and CAD
tools. The design of Jigs and Tools (J&T), which is part of
the industrial design, was executed by
external providers. Digital Manufacturing implementation
demanded having a Digital Mock-Up
(DMU) of every J&T. A new procurement policy was developed.
The J&T purchase specification
was modified to include a DMU and the simulations to demonstrate
its performance.
Another barrier was the skills of the industrialization
engineers in using PLM tools. The solution
adopted was to set up a multidisciplinary working team model,
where industrial engineers focused
on the industrial design tasks and PLM experts created the
requested DMUs and simulations. New
working procedures were defined to steer and assist such
collaboration. Industrial engineers were
trained to understand how PLM tools help in the
industrialization design process. PLM experts were
very productive in creating the DMUs and the simulations.
A400M FAL definition and characteristics
The conceptual design solution for the A400M FAL comprises eight
main stations: five structural,
two for ground test, one for interior furbishing and another one
for flight tests. The structural
stations are: one for fuselage join up, one for empennage join
up and another one for wing join up
followed by a second station for wing equipping. The fuselage,
the empennage and the wing are
joined up in parallel. Afterwards, the three main components are
joined up in the aircraft integration
and equipping station. When the aircraft goes out from this
station, it is completed regarding
structure and systems except engines and interior furbishing.
Ground tests for testing that the
aircraft systems work properly are done in two steps. The first
step in the indoors ground test
station, and the second one for test needing to be done in
open-air in the outdoors ground test
-
stations. Afterwards, interior furbishing and engines are
mounted. Finally, the aircraft enters the
flight line station, where engines first start is checked,
engine running systems are tested and flight
tests are made (Fig. 1). The FAL design rate was 3 aircraft per
month. Stations were duplicated to
process two aircrafts in parallel when having a longer cycle
time.
Figure 1. The A400M FAL stations schema.
Regarding assembly technologies, stations include precision CNC
positioning devices, and
automatic drilling and riveting machines for fuselage and wing
join up. They also include specific
tools for moving and positioning the parts to be assembled. The
FAL has also industrial means
shared between stations, such as cranes and transport
equipment.
In every station, hundreds of assembly operations are carried
out for each aircraft. Operations are
constrained by precedence relations imposed by technical
reasons. Operations are of different types:
mechanical, electrical, hydraulic, testing, sealing, etc.
Operations are executed by assembly workers
with different skills depending on the operation type. The
number of workers in every station is
high, aircraft assembly is labor-intensive. Each worker has a
specialty and is qualified for executing
all the specialty corresponding operations. Several
sophisticated J&T are needed in each station.
Therefore, aeronautical assembly stations have to be managed as
large projects. Most of the
assembly operations are very complex and must fulfill strict
procedures and standards. For that
reason, assembly operations involve a huge amount of information
that has to be provided to the
assembly worker. The creation of such information is the subject
of the Deployment Phase [8, 10].
The Digital Manufacturing A400M FAL Project: targets and
actions
The Industrial Design of the A400M FAL was a very complex
process. It was very prone to errors
of every kind, and errors are very costly if go unnoticed until
real production. PLM tools were the
answer to improve the Industrial Design process in several ways:
a) to cope with complexity; b) to
detect Product Design errors; c) to verify the Industrial Design
and to detect possible errors early; d)
to allow checking many industrialization scenarios at an
affordable cost.
The three main targets of the project were:
To build coordinated product and J&T DMUs and assembly
simulations, allowing:
The definition and validation of assembly processes.
Detection of product and J&T design errors and concurrent
engineering issues analysis.
To define process and lead times and optimize station assembly
sequences.
-
To provide a repository of all the process metadata resulting
from the Industrial Design that could be used to feed the
Enterprise Resource Planning (ERP) system downstream.
To achieve such targets a set of actions were undertaken,
comprising both personnel and
software. The capabilities to build DMUs and simulations were
provided by creating a small team
of DELMIA experts and configuring a specific technological
environment. An Industrial Reality
room, showing DMUs in stereoscopic mode, was installed, where
teams could carry out DMU
reviews. Industrialization engineers were trained to define the
process validation requirements and
to review the resulting DMUs and simulations. The DELMIA experts
created the DMUs and the
simulations. DMUs and simulations allowed validating assembly
processes and J&T, detecting
product design errors and supporting design proposals in the
Concurrent Engineering process.
DELMIA Process Engineer (DPE) was customized to implement the
AIRBUS Military model of
times. DPE is based in the Product, Process, Resource (PPR)
concept, which allows managing the
corresponding three different structures and the links between
their elements. The A400M FAL was
modeled in a process structure representing stations. Under each
station, assembly operations could
be created and their specific times data introduced. The DPE
Process Graph tool allowed managing
the precedence between the assembly operations of every station
in a graphical interface, displaying
the precedence net. The lead time of the critical path in the
precedence net could be obtained on
demand, allowing checking if the planned cycle time of each
station was fulfilled.
DPE became the repository of all the assembly process
information. In addition to the
customization of DPE, particular developments were carried out.
Specific process time features had
to be developed. Of special relevance was the calculation of
Learning Curves. An application was
developed to validate assembly operations sequences, and
optimizing workers utilization. The
application uses a heuristic algorithm to look for process
sequences that maximize workers
utilization for every station [12]. An interface was developed
to feed the ERP system with the
assembly process data defined in the development phase of the
Industrialization Design.
The DELMIA application named QUEST, a discrete event simulator,
was used to develop a tool
to simulate the complete assembly line flow using the assembly
process data stored in DPE. The
tool allowed simulating the flow of a particular range of
aircrafts running through the assembly line.
The main inputs for a simulation are: aircraft delivery
schedule, range of aircrafts, corresponding
assembly operations, product components delivered to the FAL
with their schedule and resources
quantities. The tool allows defining hypothesis about product
components delays and resources
availability. Each set of inputs defines a so-called scenario.
For every scenario, the tool works as a
what if decision tool to test if the delivery schedule can be
met, to analyze the resources utilization and the influence of the
product components delivered to the FAL schedule.
The Digital Manufacturing project results and benefits
The first result was the creation of a Digital Manufacturing
environment comprising hardware,
software and a team of skilled PLM tools experts. Digital
Manufacturing culture was initiated in the Industrialization
Engineers community of the company. A Digital Manufacturing
environment
comprises also a common repository for all the assembly process
metadata built in the project. The
repository fostered the standardization of methods.
The industrial Digital Mock-Up (iDMU) concept was devised as the
platform for all the Digital
Manufacturing developments. Ideally, an iDMU gathers all the
product, processes and resources
information: geometrical and technological. This allows building
a complete DMU and simulations
customized for any specific task. A virtual A400M FAL was
modeled, comprising all the processes
and relevant resources. Customized iDMUs were built and
processes were simulated (Fig. 2).
J&T were designed with product as context and validated by
simulations. The validations
covered functionality, kinematics, accessibility and clashes.
This practice allowed detecting
assembly operations that were impossible to be executed with
standard tools. Leading to the early
request of customized tools to providers and avoiding costly
delays due to problem detections in
real production. Assembly operations were simulated to check
assembly capabilities, accessibility
-
and ergonomics. Since process simulations were done in the iDMU,
which included product and
J&T, they allowed detecting errors in the whole production
environment. The huge benefits
obtained by this virtual validation are appraised by the fact
that five A400M prototypes were
assembled without any major modification in J&T or assembly
processes.
Figure 2. Evolution of of an industrial Digital Mock-Up along
the FAL design process.
Another significant benefit was the elimination of physical
mockups. Traditionally, costly
physical mockups were used to validate the most critical
assembly operations. Virtual validations
demonstrated that are extremely less expensive and operations
can be validated as necessary.
The Digital Manufacturing environment built during the project
produces benefits in several
different ways. Increased capability to react to deviations from
planned data is a major example.
The components assembled in the A400M FAL come from many
different places and providers.
Components delays from planned arrival dates are frequent along
the prototype production. When a
main component delay makes impractical its assembly in the
planned station, a new place and
assembly process has to be defined. In these cases, the virtual
A400M FAL allows testing as many
alternatives as required, making possible to find the optimal
place and tools to solve the issue and to
define and validate the new assembly process.
The DPE process metadata repository and the associated tools
allowed validating the A400M
FAL industrial design regarding times and resources utilization.
Literature presents similar findings
[5-6]. The validation had three steps. First, the Process Graph
online feature, to calculate the critical
path lead time of the station precedence net, was used to check
that the planned cycle of every
station was not surpassed. Second, using the assembly operations
sequence validation tool to
optimize the workers utilization in each station [12]. The tool
helped to find the worker specialty
mix and the corresponding assembly operations sequence that
optimizes workers occupation for
every station. Third, using a discrete event tool, the workflow
was simulated to validate the capacity
of the assembly line to reach the planned rate and the aircraft
delivery plan.
Finally, the Industrial Reality Room was used for assembly
operations reviews with production
managers and workers, allowing production personnel to
contribute in the improvement of the
assembly operations definition. Specific assembly operations
reviews were done as a Virtual
Training for the workers. The objective was that assembly
workers could analyze in detail the
assembly operations prior to their execution. This allowed them
to know the parts to be mounted,
the tools to be used, to identify difficulties that could be
encountered, to get a thorough
understanding of the assembly operations and to propose
improvements to the operations.
Conclusions
The A400M FAL Digital Manufacturing Project demonstrated that
Digital Manufacturing provides
a big advantage in the Development Phase of aeronautical
assembly lines. The benefits can be
summarized as follow:
Concurrent Engineering leveraged. It makes possible to do in
parallel the Product Functional Design and the Industrial Design,
shortening the development phase lead time.
Product, J&T and industrialization design errors are
disclosed in the virtual environment, avoiding the high costs of
solving them during the manufacturing time.
Costly physical mockups are eliminated.
-
Improved product quality, cost and lead times due to better and
validated assembly processes and validated designs of jigs &
Tools more coordinated with the product design.
Assembly Line workflow validated and optimized.
Improved resources utilization.
Workers Virtual Training and Concurrence with Manufacturing.
Regarding PLM tools maturity, the results showed that 3D tools were
reasonable mature,
however the integration of 3D data and metadata was not mature
enough. Similarly can be stated
regarding the industrial Digital Mock-Up (iDMU) integration and
management.
The training cost in PLM tools is low in comparison with the
returns obtained. The expected
training time for a 3D designer to become a PLM expert was
evaluated in one month.
As a final conclusion, to implement Digital Manufacturing is
absolutely necessary to have high
management support and the definition of a change management
methodology.
Acknowledgements
The authors want to express their most sincere gratitude to the
colleagues of UPM and AIRBUS
Military, who kindly collaborated in this project.
References
[1] D.H. Brown Associates, Inc.; Proving its Worth: Digital
Manufacturings ROI, 1999.
[2] CIMdata; The Benefits of Digital Manufacturing, 2003.
[3] T. Warren Liao, et al.; A computer-aided aircraft frame
assembly planner, Computers in
Industry, vol. 27 (1995) 259-271.
[4] Roberto F. Lu , Shankar Sundaram; Manufacturing Process
Modelling of Boeing 747 Moving
Line Concepts, Proceedings of the 2002 Winter Simulation
Conference, 2002.
[5] J. Butterfield, et al.; Optimization of aircraft fuselage
assembly process using digital
manufacturing, J. of Comput. Inf. Sci. Eng., vol. 7, no. 3,
(2007) 269-275.
[6] J. Butterfield, et al.; An Integrated Approach to the
Conceptual Development of Aircraft
Structures Focusing on Manufacturing Simulation and Cost, AIAA
5th Aviation, Technology,
Integration, and Operations Conference (ATIO), 2005.
[7] M. Delpiano, M. Fabbri, C. Garda, E. Valfre, Virtual
Development and Integration of
Advanced Aerospace Systems: Alenia Aeronautics Experience.
[8] F. Mas, J. Ros, J. L. Menndez, et al.; Concurrent conceptual
design of aero-structure
assembly lines, Proc. 14th Intl. Conf. on Concurrent
Enterprising (ICE), Lisbon, 2008.
[9] F. Mas, J. Ros, J. L. Menndez, Scenario for Concurrent
Conceptual Assembly Line Design: a
case study, Proc. 4th Mnfg. Eng. Society Intl. Conf. (MESIC
2011), Cadiz (SPAIN), 2011.
[10] J. Servan, F. Mas, J. L. Menndez, J. Ros; Using Augmented
Reality in AIRBUS A400M
Shopfloor Assembly Work Instructions, Proc. 4th Mnfg. Eng.
Society Intl. Conf. (MESIC
2011), Cadiz (SPAIN), 2011.
[11] T. Pardessus; Concurrent Engineering Development and
Practices for aircraft design at
AIRBUS, Proc. of the 24th Intl. Congress of the Aeronautical
Sciences (ISCAS 2004), 2004.
[12] J. Rios, F. Mas, J. L. Menndez, A review of the A400M Final
Assembly Line Balancing
Methodology, Proc. 4th Mnfg. Eng. Society Intl. Conf. (MESIC
2011), Cadiz (SPAIN), 2011.