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A materials process engineer at Renault, Nathalie Barrois, recently shared with Afera Marseille Conference attendees how Renault applies hundreds of square centimetres of tapes in each of its vehicles and the opportunities for further development in this field. The Tapes Project Manager described the state of the art of adhesive tapes in car assembly, the increased utilisation of tape at Renault since 1972, the auto maker’s system for integrating tapes into its processes, and what Renault would like to see in tape development and co-action with tape manufacturers.
The bottom line: Adhesive tapes are used everywhere in the manufacture of a car, on average several hundred square centimetres per Renault vehicle. Tape use, especially in multi-material joining applications, will only increase with the upward trend in lightweighting vehicles. Tape manufacturers and suppliers should develop adhesive tape solutions in close co-operation with car manufacturers and their strategic partners, building and maintaining extensive knowhow and understanding of the needs of automakers.
Understanding the scope of the market for adhesive tapes: Renault
Established more than a century ago, Renault is a French multinational automobile manufacturer and one of the biggest automakers in the world by production volume. The Renault Group, which consists of Renault Samsung Motors, Dacia and Renault, sold nearly 2.6 million vehicles in 2014. The Renault-Nissan Alliance is the fourth largest automotive group. The Alliance’s eight brands include Renault, Dacia, Renault Samsung Motors, Nissan, Infinity, Datsun and AvtoVAZ. These together made up 8.5 million auto sales in 2014.
Renault is a generalist manufacturer of more than 26 models of cars and SUVs, from Twingo to Espace, for private and professional use, and from combustion engines to electric motors. Operating in more than 128 countries, the Renault Group has five engineering centres across the world in France, Brazil, Romania, Russia and South Korea. The company has a customer-centric business approach focusing on well-being, affordable costs and reduction of CO₂ emissions.
The state of the art of auto adhesive technology: Where does Renault use tapes in its cars?
Because of the large number of parts, various materials and joining situations, there is a broad variety of applications for adhesive tapes in an automobile: in and on doors, pillars, seats, arm rests, consoles, sun roofs, parking sensors and emblems, and for outside accessories and stripping, airbags for harness fixation, balancing weights on wheels, and soundproofing parts for inside applications, etc. Some applications for tapes are perhaps not evident at first glance.
The main applications for cars at Renault are summarised in the table above. The most common materials used in these bonding instances are mentioned in the grey and blue columns. Adhesive tapes fulfil the need to bond a wide variety of material combinations including painted surfaces in many of Renault’s production plants.
Adhesive tapes for parts fixation: Double-sided tapes
Renault currently uses on average several hundred square centimetres of tapes in a car. This figure includes configurations in which joining with tapes is not solely holding parts together, as Renault often uses tapes in combination with other standard methods of mechanical fixation. Sometimes the areas concerning tapes are very small, but this does not mean the sealing and assembly provided by tapes is not crucial.
Renault’s specifications for tapes are primarily directly related to the tape products themselves, but there are also instances in which auto parts containing tapes are delivered to the company’s plants. Hence tape specifications are also given in parts specifications.
Adhesive tapes for joining
The field of joining techniques in the automotive industry is wide. The three competing technologies for joining with adhesive tapes:
1. The automotive industry uses many welding technologies such as resistance spot welding, laser/MAG welding, remote laser welding (in steel assembly) and ultrasonic welding for thermoplastics or thin metals.
2. Then, mechanical joining technologies such as the self-piercing rivet, friction welded rivet, flow drill screw and tack rivet (mainly used for metals), are becoming more common in the industry. They are more expensive but are used to bind different materials together when welding is not possible. Renault also has a large range of clipping solutions for multi-materials parts assembly.
3. Finally, glue bonding technologies are used for structural and semi-structural applications for the well-known gluing and fitting of windscreens and for the hemming and bonding of doors.
Adhesive tapes offer unique advantages however. Renault has appreciated these since 1972, the year of its first standard dedicated to double-sided tapes. New tape applications have gradually come on the market, and Renault has modified its specifications according to the new technologies in demand. In 1994, for example, Renault’s specifications were not as specific as they are now, and applications rarely consisted solely of tapes.
The subject of tapes is not new at Renault, but the car maker is constantly meeting new challenges in this area. Renault’s standards include specifications for all phases of vehicle life from production to end-of-life. Auto production is an important phase in utilising adhesive tapes. Renault requires good adhesion from the get-go when parts are already subjected to relative stress possibly due to the speed of production and high temperatures. Cars are also increasingly subjected to new markets where they are exposed to very low and high temperatures. Renault’s standard specifications take mechanical properties, chemical concerns about odours, and REACH requirements into account.
Because of the evolution of car manufacturing which tends toward faster, more globally accessible vehicles, Renault is constantly updating and adding to its requirements. These include guaranteeing capacity of adhesion even in the case of paintwork and less optimal (clean) surfaces and other conditions of pressure application.
What is Renault’s process for utilising adhesive tapes?
Renault specifies tapes in most relevant applications and at least defines standards to be fulfilled by tapes. Firstly, Renault indicates assembly needs and the plant process for using adhesive tapes. The supplier then proposes new products with better performance. Renault also outlines procedures for new assembly needs.
Tape suppliers are then responsible for presenting their new products according to Renault specifications. The production part approval file they produce is used by Renault to specify the tapes that will be used in the assembly of a particular part. At the same time and during the life of the project, suppliers are expected to provide assistance to Renault and parts suppliers.
Opportunities for further developments of adhesives tapes in Renault’s industry
As there is an international commitment to decrease CO₂ emissions drastically, this issue is growing in importance in regulatory arenas. Chinese government targets will converge with European ones in the coming years. This major trend has a direct impact on the auto industry and many of its suppliers: One way to reduce automotive CO₂ emissions is to reduce fuel consumption, and a way to do this is to reduce vehicle weight by focusing on materials breakdown and part design.
The current materials breakdown in a car: 75% metal, of which about 60% is steel; 20% polymers, of which about 45% are polypropylene. The tendency in automotive weight reduction is to decrease part thickness (and consequently specify greater mechanical properties), to decrease materials density (by changing materials), and to decrease surface size by redesigning parts and architecture. These activities lead to higher and very high-strength complex steels, aluminium alloys, magnesium castings, polymer matrix composites (glass, carbon and natural fibres reinforcers), thermoplastic and thermoset plastics.
Renault’s EOLAB project is the ultra-light-structured car imagined by the automaker. Steel is replaced by magnesium, aluminium and thermoplastics, providing new challenges for joining technologies in this multi-material vehicle. Choosing the right material for the right location and application without drawbacks such as costly, heavy or bulky solutions is the global trend in the automobile industry. Adhesive tapes have great opportunities here. New challenges for the use of tapes at Renault most likely lie in joining applications.
What does Renault expect from tape technology?
1. Increased performance, e.g. sealing and tolerance coverage, damping with constant force distribution, and compensation for thermal elongation in multilateral joining.
2. Materials that can undergo extensive wear in the vehicle production process, which is not easy to modify. The utilisation of tape must be compatible with current vehicle manufacturing processes which are fast-moving, subject to high temperatures and labour-intensive.
3. Light-weight fixation of multiple materials.
4. Cost-effective, easy-to-produce assembly solutions.
5. Customisation with easy assembly, e.g. without specialised body in white (no holes in sheets for outside accessories).
6. Time savings in projects with easily set up assembly and in process.
7. International engineering and production, i.e. global availability of products in all process and use conditions.
What does Renault expect from tape manufacturers?
Ms. Barrois explained that although already working in this direction with tapes suppliers, Renault needs assistance in the following areas in relation to its current development challenges:
1. Build Renault’s confidence in robust and affordable tapes.
• Adapt your proposed product to Renault’s requirements and propose standardised solutions for versatile tapes (i.e. tapes that could be used globally for any application process on any materials for any type of fixation/stress).
• Propose tapes and applications that Renault has not thought of yet.
• Help Renault to specify tapes by testing them.
• Help Renault to progress with its tapes.
2. Assist Renault and its suppliers with production part approval processes.
• Prove the validity of your products.
• Develop your knowledge of adhesive tapes in the automotive sector.
• Share product and process design rules.
3. Help Renault to capitalise on using tapes in its processes by sharing best practices.
4. Help Renault to anticipate results through mechanical behaviour simulations, because actual trials and experiments are expensive and time-consuming in the ever faster-paced project development cycles of new vehicles.
• Share knowledge about mechanisms (ageing, adherence, mechanical behaviour, etc.).
• Share knowledge about surfaces.
5. Work together with all departments involved in car development, from innovation and design to engineering expertise, purchasing, materials engineering, quality and trends, etc.
6. Co-operate with strategic partners.
About Nathalie Barrois
Nathalie Barrois is in charge of developing applications for tapes in the Materials Engineering Department of Renault. After obtaining a degree from INSA in materials science and engineering in 1989, she joined Renault, where she has worked ever since. Ms. Barrois initially handled quality assurance for the first plastic fenders on the Clio and then moved on to become project leader of research in polymer ageing, chemical analysis, polymer blend and odour research. She has also managed teams for inorganic analysis and scanning electron microscope, metrology, and electric materials and has served as an engineering leader of quality during project development for opening panels.
Questions and comments?
Tapes project manager
DEATC Materials Engineering Department - DEATCM
API : FR TCR LAB 0 35
1, avenue du Golf - 78084 - Guyancourt Cedex
Tel. : +33 1 76 85 04 69
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