Vehicle News - February 2004 (n°274)


Date : 16/02/2004 | Catégorie : Article de presse

Evolution - Fastener
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What’s the difference between a hitch pin and a wire tie? Get this wrong and it could cost your company millions in warranty bills and vehicle recalls, not to mention your job. Matthew Beecham, author of a new report from ABOUT Automotive on the automotive fastener industry, finds out how the humble fastener has evolved from a mere commodity part to a highly engineered, multi-purpose component.

There is no simple answer in fastening; no one size fits all. All technologies have to be considered. But fitting the wrong fastener for the job can lead to massive warranty costs and unlimited vehicle recalls. It can make the difference between reliability and liability. “Fasteners are not just about holding things together,” said Colin Tilzey, global product line group manager, for TRW’s automotive electronics and components business. “They can reduce vibration and seal parts, too.” The fastener market is basically divided into two camps: mechanical and chemical solutions (adhesives). While the most common techniques include mechanical fastening such as riveting, threading and welding, chemical fastening methods are increasing in importance. A major trend that affects the fastener segment is fewer part numbers per vehicle as OEMs consolidate their platforms. “It is very common to find OEMs using threaded fasteners on a vehicle that show 1, 2 or 3 millimetre differences in length. Everything else about the fastener is the same,” said Steve Wirrig, director of product marketing and strategic planning for Textron Fastening Systems. Thomas Ehrhardt, business development manager for TRW’s fasteners business in Europe added: “One of the trends in the market is to offer a universal part. In one situation, we managed to reduce 20 part numbers into one. The fewer part numbers you have, the cheaper it becomes.” Fastener manufacturers are urging the vehicle makers to ‘think outside the box’, as Steve Wirrig told us: “If you look at the primary objective of the major OEMs, they want to have a catalogue of fastener products; highly engineered, specialised and standardised products that their engineering community will use to select their fasteners. They are not allowed to go outside this catalogue which helps drive the move toward standardisation, higher volumes and therefore allow them to leverage on pricing. In some ways, that’s good for us. We certainly participate heavily in that to make sure our fasteners are considered and specified. However, it does tend to force engineers to think within a particular box. So, as we trend toward these very different types of material, we have worked with the engineering community outside of those catalogue standards to make sure that they are seeing all of the development possibilities.” The migration of creature comforts from the home to the car has prompted carmakers to re-think in-car entertainment systems as a fertile area to make profits. Demand for affordable in-car entertainment is expanding from the radio cassette player to complex integrated infotainment systems. These new technologies are also creating a blossoming niche market for some mechanical fastener businesses. Given that most electronic gadgetry needs to be wrapped in sheet metal to block frequencies from one unit to the next, this is creating more opportunity for fastener suppliers, as Steve Wirrig added: “We see the content of electronics in cars increasing significantly over the next ten years. Consequently, we see the growth of electronic fasteners rising at around 8% - 9% annually.” Another supplier predicted some knock-on affects following the introduction of drive-by-wire technologies; forecasting how fewer hydraulic pipes would result in fewer fasteners per vehicle.
Let’s stick together
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Adhesives have been used to stick automotive parts together for many years but usually in secondary applications such as hem flange bonding. In some areas of the car, however, adhesives have achieved significant design wins at the expense of mechanical fasteners and welds, based on their ability to reduce noise and vibration and to bond synthetic materials. In a recent interview with ABOUT Automotive, 3M commented: “Because adhesives and tapes allow for pleasing aesthetics and provide more design flexibility than some other alternatives, we believe the car’s interior is still the most promising area for adhesives; however, we are constantly looking for ways to make our customers more competitive and will continue to look for innovative ways to use adhesives and tapes throughout the vehicle.” As the drive towards saving weight and cost in vehicle manufacturing continues, manufacturers report an increase in the use of olefins. Bonding olefins is a challenge that all adhesives manufacturers face. Manufacturers also report a trend toward increased use of thermal formed parts. This process is used for consoles and dashes, as well as instrument and door panels. 3M added: “As always, the plants want a product that works quickly so that it will fit into their processes. They want a product that does not require ‘fixturing’ or cure times. They want to apply the adhesive and send it down the line. In addition, they would prefer the adhesive to be water based, with a heat resistance of -40oC to +105oC.” So adhesives are taking over from mechanical fastener applications, right? On the face of it, the trend certainly seems to be going that way. But it’s not that clear cut. Despite adhesive manufacturers’ claims, and with the best will in the world, adhesives and tapes cannot stick every auto component together. “You can reduce the fastener content, you can improve the robustness and the reliability of a joint, and you can do a lot of things with adhesives that you can’t do with mechanical fasteners alone, but I don’t see a trend in the future where there will be a significant decrease in mechanical fastener content due to adhesives,” said Steve Wirrig.
Coming unstuck
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So what are the limitations of adhesives? Well, not every surface is suitable for adhesives (if you don’t have an adequate surface, you can’t use adhesives to bond). There is an economic issue, too. In some cases it is cheaper to choose alternatives. Those alternatives can also be easier to apply. Okay, anything else? 3M summed up the situation: “One of the challenges we face when bonding new materials together is having the designers consider the adhesive before the design is locked in. Far too often, the adhesive is an afterthought and we are not only constrained by new materials, but also constrained by design parameters not intended for adhesives. A second technical challenge we face is the surface condition of the new materials that may demand a certain amount of surface preparation for adhesives to be used optimally. Also, some of the new classes of plastics, especially the blends, can display certain characteristics such as ‘blooming’ where the plasticizer migrates to the surface or different raw materials will act differently causing performance consistency challenges.” Another challenge facing manufacturers is in anticipating trends far enough in advance so that the group has a portfolio of adhesives and tapes that can be used with new materials. For example, in anticipation of a trend in increased use of plastics in automobiles, 3M developed its DP8000 series of structural adhesives for TPOs (thermoplastic olyolefin). Vehicle recycling is another major challenge for the adhesives industry with respect to disassembly. Carmakers are looking for adhesives that will cure within minutes (preferably seconds), retain that bond for years and then fall apart at the end of the vehicle’s life; a tall order.
Threading it all together
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Looking into their crystal balls, fastener suppliers see techniques on the horizon such as structural bonding, greater use of adhesives inside the car, more surface-attach fasteners with fewer holes in the vehicle structure. As vehicle build quality increases, the demand for self-locking fasteners that demonstrate better product quality is another growth area, say manufacturers. Alongside these technology trends, some of the major manufacturers of fasteners, such as Textron Fastening Systems (TFS), are positioning themselves as a one-stop shop for the OEM, providing total fastener supply management. Such moves follow massive investments in technologies such as cold forming, laser welding and injection moulding. TFS, in collaboration with Ford, created a full service provider (FSP) fastener management program at Ford`s Cologne plant. FSP integrates design and engineering, supply base management, inventory management, and operational logistics and sequencing, for establishing an effective and coherent service. Ford has accomplished cost reduction in supply chain managementwith a zero ppm rejection rate through the fastener management program. And yet despite an apparent transformation of the automotive fastener industry, at least in some quarters, it would seem that some things never change. Suppliers’ calls on the OEM to become more involved at the early stages of vehicle design have fallen on deaf ears. Some vehicle makers still prefer to grab a handful of fasteners and throw them at the car at the eleventh hour, as one supplier told us: “I had a phone call one Friday afternoon from an OEM, saying: ‘Our new vehicle production starts on Monday and we’ve forgotten a particular fastener.’ The OEM will remain nameless but that situation is not uncommon. You might typically get one or two of those phone calls a year. You have to turn it around in the space of two days and deliver the parts to the assembly line ready for production on Monday. Before September 11th, it was not uncommon to fly round the world with a suitcase full of fasteners. But getting a box of fasteners through as hand luggage these days is not so easy.” Further details on the automotive fastener market can be found in ABOUT Automotive’s exclusive new report: Automotive fasteners: trends and market forecasts to 2007.
INTERVIEW
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Jean-Jacques Legat - R & D Manager A Raymond
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“Mechanical fasteners” and “Adhesive fasteners”: How do you see these two fixing methods developing? These 2 types of fixings evolve in a parallel and complementary way. The mechanical fastener often remains the most tested solution and the easiest one to implement. But we have more and more aesthetic constraints and the clip fastener standard solutions are not always appropriate. We thus integrate the 2 technologies by supplying pre-coated mechanical fasteners. What technological improvements have you made in your special field of fasteners? One of the priorities of our fastening solutions is comfort in vehicles. The work on the acoustic performance of our products allows us to reduce the noise of the sound sources. Therefore, we have developed a material with adjustable dynamic properties according to the specifications. What are the next innovations expected? The current fields of research specially focus on ergonomics: - To ease the fastening fixing, - To reduce operator traumatologies, - To adapt fasteners to new technologies (e.g.: plastic wings).
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