Tag Archives: Lightweighting

Fasteners Enable Lightweighting Efforts

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Reprint from Hardware & Fastener Components Magazine, Vol. 41

Histories is full of examples of technologies whose invention long predates their actual practical introduction into society. We could say of these ideas that they were simply “before their time”. Although that would be accurate, it would probably be a fairer assessment to say that they required further maturing and the development of enabling technologies to make them work. Take, for example, one of the most iconic inventions of all-time, the electric light bulb. The earliest light bulbs were invented in the early 1800s. It would be eighty years later that Edison would discover the carbon fiber filament and create the first practical incandescent light bulbs. However, electric light wouldn’t become truly a mainstay in society for another thirty or forty years as enabling technology, such as electrical power generation, transmission and distribution, matured and became a practical reality.

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Characterization of Flow Drill Screwdriving Process Parameters on Joint Quality

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From SAE International, September 2014

Abstract: A state of the art proprietary method for aluminum-to-aluminum joining in the automotive industry is Resistance Spot Welding. However, with spot welding (1) structural performance of the joint may be degraded through heat-affected zones created by the high temperature thermal joining process, (2) achieving the double-sided access necessary for the spot welding electrodes may limit design flexibility, and (3) variability with welds leads to production inconsistencies. Self-piercing rivets have been used before; however they require different rivet/die combinations depending on the material being joined, which adds to process complexity. In recent years the introductions of screw products that combine the technologies of friction drilling and thread forming have entered the market. These types of screw products do not have these access limitations as through-part connections are formed by one-sided access using a thermo-mechanical flow screwdriving process with minimal heat. The friction drilling, thread forming process, hereto referred to as “FDS” is an automated continuous process that allows multi-material joining by utilizing a screw as both the tool and the fastener. The process uses the friction caused by the rotating screw to pierce and extrude the material. Threads are then created in this formed extrusion which allows the fastener to be screwdriven into the parts. A final torquing then securely clamps together the sheets of material. This study explores the quality design space as represented by resultant joint geometry as a function of the critical process parameters of fastener force and drilling speed. Feasible design space regions are explored to determine how process parameters affect joint geometry, and strength testing performed to validate the findings. (Article No.: SAE 2014-01-2241)

Available for Purchase on SAE International: http://papers.sae.org/2014-01-2241/

 

Self-tapping Fasteners for Lightweight Designs

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From SAE International, April 2014

Abstract:  As automotive technology rapidly provides advances in lighter weight designs and materials, the technology to fasten and join them must keep pace. This paper will explore two uniquely different fastening technologies that are being used to address some of today’s demanding application challenges in plastics and thin steel and aluminum sheet. These are two areas of application that have historically provided few good options for designers, especially as they attempt to push the envelope with progressive, light weight designs. The first technology is self- tapping screws for plastics that, although not new, are now evolving to enable smaller bosses and shorter thread engagements, and incorporate light weight design options. Although dependent on the demands of the application, these screws can be produced in both steel and, now, lighter weight materials such as aluminum and plastic. The paper will explore how these technologies can be employed by the designer to obtain desired weight reduction initiatives over more conventional threaded fasteners for fastening plastic. The second technology are self-tapping, thermal forming screws that enable fastening of thin metal sheets that normally are unable to safely accommodate a threaded fastener joint because of the minimum sheet thickness. This technology is proving especially useful in automotive body-in-white applications where multiple stacks of aluminum sheet, mixed applications of aluminum and steel, multiple stacks of thin steel, and applications into extruded aluminum or magnesium members, particularly with one-sided access are necessary. This portion of the paper will specifically explore how this technology allows lighter weight aluminum or thinner steel sheets to be used since a robust and secure threaded joint can be formed. (Article No.: SAE 2014-01-0785)

Available for Purchase on SAE International: http://papers.sae.org/2014-01-0785/