Technology advances related to automotive fasteners are generally a response to technology changes in the industries they impact, according to Fastener Training Institute instructor Laurence Claus.

“New automotive fastener technology is almost all entirely a function of being ‘enabling technology’ for recent advancements and needs in the automotive industry,” Claus told GlobalFastenerNews.com.

Almost all of these advancements are centered around today’s automotive industry efforts to “lightweight,” or reduce the weight of parts.

Interesting new technologies include fasteners that enable “flow drill screwing” for one-sided access connections of thin sheet joining (especially aluminum to aluminum), self-piercing rivets for two-sided access connections of thin sheet joining (again, especially aluminum to aluminum), FEW technology (Friction Element Welding) for two sided access assembly of mixed material joints, particularly aluminum to high-strength and ultra-high-strength steel (probably the most interesting and revolutionary of all the new automotive fastening technology), self-piercing and thread forming fasteners for thermoplastic carbon-fiber reinforced materials, high strength aluminum fasteners, mostly for powertrain applications, and ultra-high strength, Austempered steel fasteners.

“Additionally, although not really “new” technology, there have been recent advancements in coatings that act as a di-electric to protect against galvanic corrosion of dissimilar materials in fastened joints and a continuing maturation of thread forming technology and practice, particularly in thermoplastic, thermoset, and light metal applications,” Claus added.

Salim Brahimi, Director of Engineering Technology at the Industrial Fasteners Institute, said automakers are reducing weight and improving fuel efficiency by pushing the limits of high strength steels.

“Some European manufacturers have implemented fasteners as high as 1600 MPa using martensitic and/or bainitic steels.” 

This trend is also beginning with U.S. OEMs.

“The main concerns are to increase strength while retaining an acceptable level of ductility and separately an acceptable level of susceptibility to hydrogen embrittlement,” Brahimi added. “The potential advantages are reducing size and/or the number of fasteners.”

Automotive OEMs are also exploring the use of aluminum fasteners, Brahimi explained.

“So far aluminum fasteners have had limited use in the auto industry, with some expectations such as the new Ford F150 aluminum body. This is especially true with critical fasteners used in the engine and transmission.”

Proper materials and manufacturing technologies already exist; however, the supply chain is not adequately developed to supply the auto industry.  But Brahimi said this trend will change in the coming years.

“This is changing as the OEMs are working with fastener manufacturers, some of whom have a long history in the aerospace industry.

“The challenge is in designing critical joints that are well suited for aluminum fasteners without the risk of galvanic corrosion between dissimilar metals.”

Advances are not limited to materials, according to Brahimi. OEMs are also looking at assembly.

“The use of higher strength fasteners, tightened to higher and more critical preloads, implies a need for even more accurate control of tightening strategies.”

Torque and angle method of installation is the most cost effective and reliable approach.

“It will be used more systematically, and not only for critical engine fasteners. The use of other techniques such as ultrasonic load measurement during installation will likely a grow where the nature of the application warrants the added costs.”

How are automotive fastener manufacturers preparing for these changes?

“The truly proactive fastener manufacturers are listening to their customer’s needs and either investing in innovation and R&D to address the unique challenges of automotive lightweighting or they are partnering with fastener technology initiators to further develop or license innovation and bring it to the market,” Claus told GlobalFastenerNews.com.

Automotive fastener manufacturers are always faced with the difficult challenges of supplying products that meet very stringent quality requirements at mass produced commodity prices, Brahimi added.

“Suppliers of critical automotive fasteners must redouble their R&D efforts and continuously improve manufacturing capabilities to meet these challenges.”

These efforts must be combined with even more robust quality assurance systems designed to produce high quality fasteners consistently, Brahimi noted.

“The challenges of mass production also mean that automated 100% inspection is inevitable for larger proportions of products. Inspection systems will continue to be improved systems by increasing the use of vision, eddy current and functional inspection technologies.

“In this respect, automotive fastener manufacturers lead the way.”

Are automotive fastener manufacturers studying aerospace innovations to reduce weight?

While it’s easy to assume that automotive fastener manufacturers are influenced by advances in aerospace, there is little interchange between industry segments.

“Aerospace fastener manufacturers could learn a lot from automotive regarding elimination of cadmium plating, thread forming fasteners (for non-critical joints- perhaps many in interior accessory applications, as an example), and new, high torque transmitting internal recesses,” Claus noted.

“The automotive industry could learn a great deal from aerospace manufacturers related to lightweight materials (aluminum and titanium), workmanship, and fasteners rated for fatigue.”

The needs of the two industries are very different, according to Brahimi.

“The auto industry need higher volumes at lower unit cost. However, due largely to the high degree of automation during assembly processes, there is a very low tolerance for non-conforming parts actually reaching the assembly line. 

“On the other hand, the aerospace industry has a significantly lower volume requirement and very stringent quality and certification requirements, which inevitably result in significantly higher unit costs.

This reality would seem to suggest that automotive fastener manufacturers have little to learn from aerospace counterparts. But according to Brahimi, that’s not true.

“From the perspective of weight reduction, the auto industry as a whole must inevitably learn from the aerospace industry relative to innovative structural designs and fastened joints using lighter weight materials such as aluminum, titanium and heat resistant steels.”

So what’s driving automotive industry changes?

“Predominantly lightweighting, which is a response to the upcoming CAFÉ (Corporate Average Fuel Economy) requirements,” Claus stated. “Additionally, any other technologies that address long-standing challenges such as galvanic corrosion, hydrogen embrittlement, and ability to generate and sustain high tension loads in joints in the most economical process possible continue to drive changes and innovation in the automotive industry.”

Brahimi agrees.

“Weight reduction to improve fuel efficiency is the primary driver at the moment.

“However, the lessons learned with combustion engines can also be applied to reduce energy efficiency of electric and hydrogen fuel cell vehicles that will inevitably become more prevalent in the future.”

The FTI/IFI Automotive Fastener Technology – Advanced CFS2.0 is being held on April 24-25, 2017. For more information, contact FTI. Web: fastenertraining.org