Looking for an alternative to welding in some assembly operations? Think that there ought to be a way that some mechanical fasteners could be made more efficient? Interested, perhaps, in joining pre-painted materials? An answer to all of these questions is a system from AKH Inc. (www.akhfas-ner.com; Indianapolis), called its FAS-NER System. While the system has been available for the past few years, there have been several upgrades and improvements to the process.
Essentially, the system makes use of a self-piercing headed or headless fastener; there are 21 standard sizes. It is cylindrically shaped overall, with concave sides so that the fastener resembles an hourglass. The fastener is produced with hardened aluminum or high-carbon steel. In addition to the fastener, there is a tooling system. In operation, the pieces to be held are clamped, then the fastener is driven down into the materials to be joined, starting with the softest or the thinnest of the two. Initially, the fastener pierces the materials, then there is shearing of the materials and the slugs pass down into an opening in the die-set. There are coining rings in the lower die-set such that there is material flow around the concave sections of the fastener. As a result, there is an assembly with the fastener flush to the surfaces.
However, they've found that when there are very thin gauge materials being joined it may be helpful for there to be an external head, so they've developed the Double Headed FAS-NER to accommodate that.
Many manufacturers are looking at using pre-painted materials in operations. However, joining them may be challenging. For example, spot or arc welding will cause the painted surface to be marred due to the heat input. According to AKH, "Cold forming processes (i.e., orbital/radial riveting, staking, and clinching) may destroy the integrity of the coating and in turn may require a secondary process to prevent or inhibit corrosion." Bolts, screws and rivets may require a pre-punched hole, which is an additional processing step. So they've developed color-matched pre-coated FAS-NERs that are inserted directly into the coated material. Because they are flush to the surface, aesthetics are retained.
Another development of note is the implementation of the microprocessor-based assembly monitoring system from Promess on AKH systems. This system utilizes force and position sensors. There is a "taught" profile of the force and position for a good assembly, then during press operation, the actual measurements are compared against the profile to help assure that the process is performed within the predetermined tolerance window, thereby assuring a good assembly.