MEDIA SPOTLIGHT: Automotive Looking to Fastener Alternatives

John Wolz

Articles in Media Spotlight are excerpts from publications or broadcasts which show the industry what the public is reading or hearing about fasteners and fastener companies.

Threaded fasteners are the No. 1 cause of automotive product failures, but most of those failures are due to engineers selecting the wrong fastener for the job.
�I don�t want to sound like an anti-threaded fastener zealot,� Sandy Munro told Cahners Publishing�s Automotive Industries. �But the No. 1 cause of product failure in my studies is threaded fasteners. No. 2 on the list is rivets. Third, I see things like hitch pins or wire ties, and then way down at the bottom of the list are self-securing snap-fits.�\
Munro acknowledged that fastener manufacturers are hitting six-sigma quality levels.
�Fasteners are a pre-engineered solution that allow us to just grab a handful and throw it at the problem at the last minute,� Munro told Gerry Kobe in an article headlined �Keeping It Together.�
�But automakers shorten cycle times so they can change things late in a program, and that doesn�t allow time to engineer the best fastening solutions. The more companies stall before committing to a design, the more incorrect fasteners and warranty work you are going to get.�
If automakers really want �answers to what causes product failures and recalls, they need look no further than what holds their vehicles together,� Kobe wrote.
Mechanical fasteners, including riveting, threaded fasteners and welding are �still the darling of the auto industry,� Kobe found.
�Drawn arc stud welding is one of our core products, Steven Bleakley of Emhart Fastening Teknologies told Kobe. �We have developed a closed-loop feedback system for this technology that makes it foolproof. It virtually eliminates the possibility of a cold weld in the body shop.�
Previously GM used about 20 such studs per vehicle. With the new technology a new truck model used 129 studs per vehicle.
�Variations on this technology also allow fastening of brackets, nuts and other attachments that make a single fastener technology multipurposed and highly economical.�
John O�Brien, global director sales/product for PEM Fastening Systems, said telematics, navigation systems and ABS have added new specialty fasteners.
Automakers generally create special fastener requirements. �They tell us our product is being designed out, but, in fact, the application opportunity is expanding,� O�Brien was quoted.
Phillips Screw Company president Mike Mowins observed that ever-changing corrosion, strength, thread and materials criteria �providing superior performance, tools and being able to solve problems differentiates you from a commodity supplier.�
�We have done work with JCI, Honda and DaimlerChrysler on a number of applications that helped them solve problems,� Mowins said. �Sure we supply screws, but if we identify and resolve problems with rework, scrap, damage or worker injury, then we are much more than a commodity supplier who just supplies parts.�
Kobe noted that rivets, particularly tubular self-piercing rivets, are an ideal choice for high-volume applications in soft material like aluminum. Aluminum-bodied vehicles like Audi�s AS use this technology, as supplied by Emhart, and it also holds potential for joining dissimilar soft materials, such as aluminum and plastic – a definite future trend.
Products that simply don�t require fasteners have huge potential, but automakers have resisted snap-fits. In spite of the allure of higher quality and lower cost, they take time to engineer and are not conducive to last minute changes. Still, there are examples that show promise.
�Fasteners are a feature you�d rather not have in your design,� Delphi engineer Brian Staser said. �If you look at our Super Plug door module, we designed a plastic frame that eliminated 61 separate pieces.� That is used in the new GM minivan and Malibu.
The Super Plug was designed with a snap-fit speaker, handle, latch and window lift motor. The minivan version has just seven threaded fasteners and one rosebud fastener, compared with 26 threaded fasteners and 12 rosebuds for the conventional design it replaced.
�People are afraid of snap-fits, because our automotive engineering base just doesn�t do these things,� Munro observed. �They are happier to conclude that snap-fits fall apart; but evidence shows that�s not true. The cell phone you drop on cement once a week is probably a snap-fit, and so is everything else that�s really important. Medicine bottles are snap-fits. Nuclear waste containers are snap-fit by law. And by the way, people aren�t held together with screws and rivets either � we�re all snap-fits, and I can�t remember the last time I saw anybody fall apart.�
Munro points out that automotive OEs have shifted a lot of design responsibility to suppliers, who could probably make fasteners disappear if they had clear specifications that didn�t change.
Munro warned that Toyota and Honda are taking some of the more complex component designs back in-house, and that robust snap-fits are already starting to show up in those systems.
Adhesives are growing rapidly in automotive use, with the current growth in interiors. Applications such as headliners and door trim have moved from mechanical fastening to almost exclusively adhesive. The chemicals give better finish, easier build, greater durability, lower weight and lower cost.
Equally challenging is trying to stick new engineering polyolefins together. �Some of these new plastics are so greasy they are almost like sticking to Teflon.� says Brian Brady, market supervisor for 3M Adhesive Division. �The new materials are less expensive and even lighter than traditional plastic, and they are very recyclable. So recyclability is going to make it increasingly important for any adhesives company to be able to break a bond as well as make one. The OEs want an adhesive that will cure instantly, have a phenomenal bond and then 15 years later fall apart on command.�