virtual verification of an aircraft final assembly line industrialization an industrial case
TRANSCRIPT
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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],
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
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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
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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.
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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
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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.
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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.
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