2 M.A.EL HANI, L.RIVEST, C.FORTIN
efficiently support the work of propagating a change from an element of information that
defines a product, to other elements of information that define the Manufacturing Work
Instruction (MWI) of this product.
Ideally, the process planner would want the following to be true: «Greatly improved
knowledge management occurs because all types of product definition information
become associatively linked to the manufacturing processes and tooling designs when
Digital Manufacturing is used within a broad-based PLM initiative. This preserves, in
fact increases, the value of data. The result is that, as the product design changes, process
and resource plans can be more quickly and accurately updated». [CIMdata Inc.]
However, what is observed in practice differs from this ideal. Managing and
propagating an engineering change from the design definition to the process plan remains
basically a manual operation. Here, we distinguish Change Management and Change
«Engineering Change Management (ECM) is an important component of PLM.
ECM modules in current PLM solutions conform to the industry-standard CMII closed-
loop change model. They provide customised forms and pre-defined work-flows for
creating and processing change requests, change orders, etc. » . Engineering Change
Propagation differs from ECM. It consists of the action of integrating an engineering
change into the impacted pieces of information. Propagating changes between
geometrical data are managed and facilitated, to some extent, by CAD systems through
constraints previously established between elements of the involved models.
In industrial practice, when an engineering change is brought to a part, for example to
a tolerance, managing and propagating its impact through the different organizations
involved in the product development to the relevant portion of the process plan, tooling,
inspection document, etc., is highly complex and basically reliant on human expertise.
This paper examines some issues involved in propagating engineering change to the
process plan and identifies limitations of current PLM solutions involved in the
engineering change propagation process.
An in-depth study of the challenge related to engineering change propagation to the
manufacturing process plan is presented first. Some results of a case study are described;
an IDEF0 model for a manufacturing process planning department is presented, as well as
an overview of a proposed dashboard solution.
Challenge and approach
During the development of complex products such as those found in aeronautics, the
Manufacturing Work Instruction (MWI) development constitutes a complex process that
uses a significant number of stakeholders, documents, and applications. The task of the
manufacturing process planners is initiated from engineering drawings to lead to the
MWI. A large portion of this work is based on the process planner’s know-how. The
development process of the MWI could be schematized as shown in figure 1, where Fi F’i
and Oi are defined as follows.
Fi: Feature of the engineering drawing: it can be a dimension, a surface quality, a
tolerance, a special treatment, etc.
4 M.A.EL HANI, L.RIVEST, C.FORTIN
informational objects of complex MWI documents are impacted by an engineering
change and in which way.
The lack of an information structure to support the propagation of an engineering
change seems to be the principal reason for this problem. This structure of information is
composed by informational objects and their links. However, if the granularity of the
considered informational objects is established at the feature level, the multiple links that
relate an engineering feature to a MWI feature are from being completely documented
An interesting approach to solve the engineering change propagation problem consists in
managing the various links between technical objects (Maurino ) involved in the MWI
development process. Giguère  successfully used this approach to propagate changes
within geometric models belonging to the engineering domain. Michaud  used it to
cross the Engineering domain boundary, and propagated changes up to the tooling but
considered only the geometrical aspects. In both cases, the approach was used to solve
some well circumscribed and formalized problems (a limited number of less complex
links were controlled and formalized1
), but was not generalized.
In a general context involving multiple domains, where the level of abstraction is high
and the process is more complex, it is difficult to identify all the informational objects
involved and their links, as is the case with the MWI development process. In order to
help solve this problem, taking as a starting point the principal ideas of the approach
based on links management (Michaud  and Giguère ) and that proposed by
Eversheim , an approach with two components was proposed within the context of this
Component A) Documentation of the MWI development processes: This
component aims at studying in great detail the MWI development processes and the
Engineering-to-MWI change propagation process. This component’s objective is to
identify the principal informational objects involved and their links. The links between
the informational objects are based on the activities model and methods model co-
ordinately with the reference model suggested by Eversheim . The IDEF (Integrated
DEFinition) was used to apply this approach, mainly IDEF0 (activities model). Before
building the IDEF0 model, two business maps describing the MWI development and the
MWI modification processes were elaborated.
Component B) Gathering and analysis of business requirements for change
impact analysis: This component aims at identifying the business requirements of the
manufacturing process planners related to the study of the engineering change impact.
Based on interviews, this component also aims at proposing the ideal solution that
facilitates the engineering change impact study and its integration.
The approach described above was applied and validated with the manufacturing
process planning department of an aeronautic company. The results are presented below.
The informational objects are known and the task-specific knowledge conveyed by each link is
6 M.A.EL HANI, L.RIVEST, C.FORTIN
manufacturing process planner during the MWI development process (the reference
process and the change propagation process).
The model begins on the level "A0" (Develop the MWI of a part), which is the
principal activity (figure 2). Then, this activity is broken up into three activities (figure
3): A1) Elaborate the MWI folder (equivalent to the reference process of the MWI
development); A2) Modify the MWI folder (equivalent to the change propagation process
of the MWI development); A3) Validate the MWI (to start part production).
Due to the IDEF0 model size (201 activities) the activity "A21" describing the
engineering change impact study was selected to be described below. This activity was
decomposed into two levels and three diagrams are shown below (figures 4, 5 and 6).
The IDEF0 model shows that the manufacturing process planner has to take many
decisions to propagate engineering change on the MWI. These decisions could be to
cancel a request for tooling, which involves notifying a specific stakeholder involved in
the MWI development process. Actually, the PLM and workflow solutions offer many
capabilities to easily send information, to follow up deliverables and to notify
stakeholders but they can’t help manufacturing process planners to take decision in case
of propagating engineering change. The lack is essentially due to the fact that a great part
of the knowledge and information involved in the MWI development process is still non-
captured by PLM systems.
Analysis of the business maps reveals that the MPP, which leads to the development of
an MWI folder, is a very complex process that heavily relies on the process planner‘s
expertise, who needs to act on multiple pieces of information provided by various
sources. This complexity, coupled with the vast amount of engineering and
manufacturing features involved in MWI development, leads us to consider that capturing
the links that associate these features was not within our reach. However, understanding
the organization of the activities involved in MWI development, as per the IDEF model,
also leads to another important conclusion: due to this complexity, the process planners
must have a clear vision of all the ongoing and coming tasks performed by all the actors
involved in order to better carry out the change’s impact study. Thus, even without being
able to capture and manipulate the links that exist between the involved pieces of
information, there is still a need for a solution that offers a centralized vision of all the
process planning tasks and deliverables. This target appears as a viable alternative that
would still bring improvements to the change impact study and integration to the MWI.
The various actors involved in the process have validated this conclusion.
A quantitative analysis of the ‘informational objects’ contained in the IDEF0 model
demonstrates that a significant part of the informational objects of the MPP is contained
on paper (mark-ups on the drawings, check-lists of deliverables, approval sheets, etc.),
which leads to conclude that an important portion of the MWI development process is
still not covered by a software application. An analysis of the information included on the
IDEF0 model revealed that at least 35 % of the ‘informational objects’ manipulated by
the manufacturing process planners are not located in PLM software . Hence, the
importance of paper, the significant number of software tools, the large number of tasks
and actors involved in the MWI development process, are multiple factors that confirm
the process planners’ needs towards a solution enabling visibility into the process. The
10 M.A.EL HANI, L.RIVEST, C.FORTIN
• Manufacturing process planner’s deliverables list and status.
• Manufacturing process planner’s tasks list: it contains a list of the main tasks to be
performed by the process planner and is linked to the status of the deliverables. When
a deliverable is released, the associated task is displayed as completed.
• Project deliverables overview: For each actor involved in the MWI development
process, it gives an overview of his deliverables status. It also allows the
manufacturing process planners to dig through them using direct links to others
systems (CAD, ERP, MES, …).
• Communication window: it allows the manufacturing process planners to chat with
the different actors involved in a project. Moreover, it captures all the
communications related to a specific project.
The dashboard solution requirements are illustrated in , it provides a global idea of
the proposed interface and functionalities. It will be used as a guide for a future
development of the solution or for the acquisition of an off-the shelf solution.
From a scientific point of view, the maps and the IDEF0 model enabled us to make an
inventory of the informational objects involved in the MWI development process. This
allows us to progress towards the control of change propagation, by the identification of
these informational objects as well as some associations between them. The maps and the
IDEF0 model also made it possible to document, in detail, the activities of manufacturing
process planning to improve the understanding of the study of a change impact; such a
study often relies on the process planners' expertise.
Although many editors of PLM software promise to offer a global canvas of the
product development domain, a long journey remains ahead by the PLM systems. The
study presented in this paper confirms that there is a major area of the product
development process that requires more attention in order to achieve the PLM goals; it is
the manufacturing process planning for complex products.
1 Nlkhil, Farhad & Debasish (2005) ‘Systematic decision support for engineering change
management in PLM’, Proc. of the ASME, DETC2005: 25th Computers and Information in
Engineering Conf., p 827-838.
2 M.Maurino (1993) La gestion des données techniques, Masson, Paris, ISBN: 2-225-84518-2.
3 F.Giguère (2002) ’Application des liens multi-modèles à la conception mécanique’, Master
thesis, Sherbrooke University, Quebec, Canada.
4 M.Michaud (2004) ‘Méthodologie de modélisation unifiée pièce-outillage en CAO
aéronautique : Application aux tôles et gabarits de découpe’, Master thesis, École de
technologie supérieure, Quebec, Canada, N. 18279412.
5 Eversheim, W.; Bochtler, W.; Graessler, R.; Koelscheid, W. (1997) ‘Simultaneous
engineering approach to an integrated design and process planning’, European Journal of
Operational Research, v 100, n 2, Jul 16, p 327-337.
6 M.A.El Hani, L.Rivest, C.Fortin (2006) ‘On specifying an information management tool to
support manufacturing process planning in aerospace: A case study’, Proc. of the ASME,
26th Computers and Information in Engineering Conf., 2006, DETC2006-99231.