Is PLM (Product Life-cycle Management) a tool, a method, a concept?
Each actor, each user of the PLM presents a different point of view on the subject. Thus, the objective of this resource is not to «make a course» on the PLM but rather to present the views of PLM actors (industrialists and teachers) and many pieces of information and reflection on this theme to enable teachers to better decipher what each can put behind these three letters according to their profession and position in the company, and to understand the possibilities and operation of a PLM platform for use in design offices.
A glossary of commonly reported existing acronyms related to the MLP is presented at the end of the resource.
1 - Introduction
The PLM (Product Life-cycle Management) is a topical topic in the majority of large industrial companies. In the automotive industry, in all manufacturers and high-ranking suppliers, in the aerospace industry, PLM platforms are used. As the PLM has only been deployed for a few years, feedback is still limited. However, while the effects of using PLM on improving business performance are still difficult to determine, it is already possible to analyse the changes induced by the implementation of the PLM on the working methods and on the structuring of the project approach.
We will note that the structuring of the PLM approach is more suited to routine product design (redesign) than to the design of innovative products. In particular, it is necessary that the PLM is based on a robust design approach specific to each company. The PLM will therefore be presented as a tool for the most effective application of the design method chosen by the company.
2 - The industrial context
In a globalised economic context, companies developing industrial products in large series (automotive for example) or highly complex industrial products (aeronautics) are obliged to survive and develop to achieve ever more ambitious quality goals, costs and deadlines.
In order to meet this challenge, new development concepts are needed and innovative methods and tools are developed to achieve the objectives. Among the notable developments of recent years, we have noted the following points.
2.1 - Generalization of numerical simulation
The widespread use of simulation to predict the behaviour of systems prior to their physical implementation has led to considerable reductions in costs and delays.
One of the consequences of this evolution is that a large number of numerical data (CAD data, simulation results, material data, test results) are available to the actors of the project. These data relate to the product being produced but also, in the context of the redesign, the solutions renewed (thanks to capitalization). The archiving, versioning and accessibility of these data (an optimal exploitation of the available data in short) are one of the motivations for the development of PLM platforms.
Figure 1: Available data
2.2 - Acceleration of design cycles and multiplication of versions
The competitiveness of industries depends on their ability to renew and expand their product range according to the needs expressed. The lifespan of a product range is becoming shorter, restyling is becoming more frequent... and, as a result, design cycles are becoming shorter to ensure greater responsiveness to customer needs.
This applies to all industrial sectors. As an example, we compare below the number of versions available for a large series vehicle of the 1980s and an equivalent model in 2007.
• From 1985 to 1993: Peugeot offers the Peugeot 309. This model is offered in two bodywork (3 and 5 doors), 5 different engines after restyling (4 engines initially) for 22 different versions. In 1985, the design time for an automobile model was about 6 years.
• 10-15 years later, Peugeot offers the 307, 6 bodywork in the world (3, 4, 5 doors, station wagon, SW, convertible coupe), 7 different powertrains... Without including in this list the choice of options, approximately 120 different versions are offered for sale if one includes the choice of bodywork, engine and finish.
2.3 - The multiplication of stakeholders
The geographical breakdown of project groups and the development of subcontracting at national or international levels require:
• An operation by industrial projects allowing companies and their suppliers of different ranks to work according to objectives, an organization, a common schedule,
• The transfer of business skills and the capitalization of knowledge and know-how of the company,
• Data accessibility and management of information rights.
2.4 - Consequences
To support these developments, the concept of the PLM is therefore to provide the company with a structure and a tool allowing each actor of the project to obtain the right data at the right time.
In our analysis of the PLM, we will separate the following two aspects:
• The information system allowing each actor to have access to the key data of the product at every moment,
• The definition of the unique product for all actors in each phase of the design, “integrated” into a chain of digital tools.
The “information system” aspect represents the main contribution of the PLM and implies major changes in the way businesses operate. The “data” aspect, through the quality of the data and the problems of data transfers produced between different applications, is also an important issue, but mainly depends on the work of software publishers.
3 - The information system at the heart of the PLM
3.1 - The system configuration
The heart of the PLM is the information system. It is essential to note that the PLM does not define the sequencing of the project, the product validation criteria or criteria at its different phases, the different product models, the set of business data or their structuring: PLM is not a design method per se and it is up to the company to define these parameters and then integrate them into the PLM system. By analogy with the operation of a relational database (i.e. like SQL, which is used on many sites), the PLM system corresponds to the software managing the implementation of the database and the requests that are addressed to it, while the system configuration corresponds to the structure of the database and the relationships between the different fields of the database, which are specific to each company and each application.
This view of the PLM is, however, rather theoretical in the sense that, in the current offer of some software, the configuration is strongly linked to the choice of software and the design is strongly centralized around the CAD (geometric model) of the product.
3.2 - The life phases of the PLM
The life-cycle concept of the PLM is not the life-cycle concept of the use of the product presented in Functional Need Analysis (see resource « Functional Need Analysis»): the life-phases of the PLM are the life-phases of the product data. Of course, the nature of this data will change as the project progresses. For example, if the design method used by the company is Predictive Control of Services (see resource " Predictive Mastery of Services: Concepts", the product will exist in the form of a specification of the services to which will be added a functional specification, a specification of the operating conditions... then the data of the simulations and tests used for the dimensioning and validation.
The phases of life that interest us in the PLM are those that allow us to characterize the evolution of numerical data. The following life phases are generally retained: creation, modification (versioning), validation, dissemination, capitalisation, reuse.
We illustrate below these different concepts of life phases: the configuration of the PLM system adapted to the company’s design method allows the application of simultaneous engineering. All phases of product realization are taken into account in the system. Ideally, a modification made by a user of the system will be immediately impacted on the entire product and all the actors concerned by this modification will be immediately informed. These are different versions of the complete product that evolve as the project progresses.
Thanks to the system, successive iterations of the complete product are created:
- Staking serves to freeze some design choices
- Changes made by a project actor are impacted on the entire product
3.3 - Manage access rights
In addition to managing the life phases of digital data, an essential contribution of PLM is managing the access of different users to this data. The stakes are multiple in projects involving a parent company and suppliers of different ranks in the context of the realization of a project. Each player, depending on its role and company, has different needs (some have the task of implementing the product by creating or developing digital data, but have no right to modify external data at their borders study).
Confidentiality issues between different providers of the same rank are also to be managed.
In a simplified way, we will remember that the data may be accessible or inaccessible in viewing, reading and writing, and undergo operations called check-in and check-out corresponding to a data labeling (data being modified, data being modified).
See “Appendix: PLM User Vision” which illustrates a PLM user journey and the resulting status of PLM data
4 - The digital channel
4.1 - Compatibility between applications
For a PLM system to function on a project-wide basis, compatibility between CAD and business software must be ensured.
Simulation tools are developed at the product and process levels. The tools developed take into account an increasing number of physical phenomena (to integrate all the life phases of the design into the use) and the same numerical models must be able to be used for geometric studies (virtual 3D model) and simulations (product/process). These simulations are increasingly performed on a complete system, not piece by piece, and the corresponding numerical resources are shared. The great difficulty is therefore to structure and coordinate the work of analysis and to restore the results in a form (of forms?) usable by a maximum of functions in the company and to be able to integrate this information into the life cycle of the product.
During the first phase of simulation explosion, many business simulation tools were developed, which did not necessarily have links between them. It was difficult to talk about the virtual model of the product since we were dealing instead with a set of models not necessarily compatible with each other.
To make PLM systems efficient, it is necessary to ensure perfect communication between the different applications to lead to the creation of a single digital model. If we compare the PLM to a huge relational database, the great difficulty is to guarantee the functioning of all links. However, it is on this condition that a modification made by a project actor in the morning can be impacted on the entire product and above all validated to the final product realization criterion immediately.
4.2 - The quality of numerical models
In order to solve the problems of the quality of the numerical models, it is necessary not only that the models are compatible with each other, but also that there is no loss of quality during data transfers: for the time being, there is not a single digital model, but rather a set of digital models not necessarily 100% compatible with each other. Some data provided by one application must therefore sometimes be post-processed for use in another application.
The technical challenge is mainly to ensure field transfers (for mesh sizes and simulation results) from one stage of the product model to the next.
4.3 - Size of numerical models
Management must also take into account the increasing size of models. The volumes of data to be exchanged reach sizes expressed in terabytes ( 1 TB = 1000 GB = 1012 bytes). Exchanges between project actors should therefore be limited to what is strictly necessary.
To this end, tools for the exchange of data “in writing” and “visualization” are being developed. In particular, the «full web» visualization tools, which make it possible to visualize a model stored on a server by simply connecting to that server via an internet browser, are taking an increasing place in the systems of management of product data. These innovations combined with the development of PLM make it possible to solve the problems of loading digital models and exchanges between machines: opening large complete models in a business application could sometimes take hours, and the gain brought by the «full web» visualization of all or part of the model is in this obvious context.
5 - An educational point of view
In high schools (in BTS sections for example) and schools, PLM systems are beginning to be deployed. Obviously, the main problem is to qualify and quantify the potential contribution of these systems in terms of the acquisition of skills by students. We give here the example of a PLM project carried out in Supmeca Saint-Ouen as part of the training of engineering students in 3rd year, a few years ago;
5.1 - Description of the project by educational objectives
The educational objective of the project is to:
• Implement the digital chain (limited to CAD, FE and multi-body simulations) by integrating data obtained from tests on components of the real product,
• Embrace a collaborative engineering approach.
Logically, it was decided to test a PLM (Winchill) platform from PTC Software in order to familiarize students with the digital chain and collaborative work in an information system.
5.2 – Design approach and tools used
To use the PLM platform in a suitable field of application, the design approach is here a routine design or re-design approach
The different stages of the project are:
Iteration 0: analysis of the existing through tests and simulations. Measurement of the gap between the expected service functions in the specifications provided and the service functions performed by the product under study,
Iterations 1 to n: Redesign the system to reduce the gap between expected and actual. Each iteration corresponds here to a new version of the complete model of the product (including the skeleton of the part, the CAD of the complete product, the results of the simulations carried out to validate the performances and the answers of the tests). The advantage of using PLM in this project is that all the actors are informed of the modifications made and the impact on their work through the configuration of the system.
For example, a modification of the geometry of a part of the system will be immediately transmitted via the digital model and via the messaging system to the EF simulation manager, to the multi-simulation managerto any other actor who will have to take this change into account.
6 - Conclusion on MLP inputs
The PLM provides tools, based on an information system, to manage the intensive use of simulation, the different versions of a product, and the collaborative work in the presence of many subcontractors and suppliers. The idea is to represent all the data of the product in digital form and to share them among all the actors of the project, assigning to them rights of access and/or modification according to their roles, so that any changes to the product model (or its environment) are passed on to all concerned.
7 - Abbreviations
The main abbreviations used in the field of PLM are:
- PDM: Product Data Management
- SGDT: Technical Data Management System
- ERP: Enterprise Resource Planning
- PLM: Product Life-cycle Management
- MPdP: Predictive control of Services
- KM: Knowledge Management
- CFAO: Computer Aided Design and Manufacturing
- PPR Model: Products, Processes, Resources
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