Ultra high-strength steel, magnesium, composites, bioplastics—manufacturers today are dealing with myriad new materials designed for specific applications. In many cases, these space-age materials can’t be assembled with conventional, off-the-shelf fasteners. Rather, special fasteners with unique designs are required.

Here’s a look at some of the latest fasteners.

Threaded Inserts for Soft Metal Parts

Image: E-Z LOK

E-Z LOK solid-wall threaded inserts are ideal for repairing or reinforcing threaded holes in soft metals such as aluminum, magnesium and cast iron. External threads are standard size and pitch, so they can be installed with standard drills and taps. The inserts can be installed with a screwdriver, a bolt-and-jam nut (except IC series), or an optional power drive tool.

These inserts will not back out or vibrate loose. A pre-applied, microencapsulated adhesive begins to set immediately upon installation, and the newly installed insert is fastener-ready in 3 to 5 minutes. Despite their firm hold while in use, the inserts can be removed with a bolt extractor, which overcomes the resistance to torque-out produced by the adhesive. They can also be removed by heating the insert to a temperature above 300 F, at which point the adhesive will release.

The inserts are available in thin-wall, standard-wall, extra-heavy-wall, screw-locking and automotive designs. They are available in carbon steel and stainless steel. Stainless steel threaded inserts are perfect for applications requiring additional corrosion resistance, as well as food, beverage and other clean-critical applications.

E-Z LOK
www.ezlok.com

Thread-Forming Screws for Bioplastics

Image: Arnold Umformtechnik GmbH

The Remform II HS high-strength thread-forming screw is suitable for use in bio-based composite materials. The fastener’s rounded thread profile has been specifically designed fastening high-performance plastics. It is used when a high preload force and high loosening resistance are required.

The screw has an asymmetrical thread profile with a rounded flank tip and curved load flank. This geometry is designed to match to the flow properties of plastic and enable the material to be gently displaced. The screw also features an optimized, enlarged thread core, which significantly increases both the breaking torque and the tensile breaking force of the screw. This leads to a more stable connection between the two parts of the joint, but also allows for a higher assembly torque when joining high-strength plastics without the risk of screw breakage.

Thanks to the combination of radius profile and steep load flank, the plastic flows towards the load flank during installation, ensuring good flank coverage. By reducing the load flank angle to 10 degrees, the radial stresses are significantly reduced. This generates a low driving torque despite the high thread overlap and reduces the risk of cracking in the plastic due to the lower radial expansion.

Compared with standard Remform screws, failure force and failure torque in bioplastics can be increased by around 20 percent with the Remform II HS. The fastener has been successfully tested on Tepex bioplastic from the Lanxess Group, a 100 percent bio-based composite material with a matrix of polylactic acid reinforced with flax fibers.

Arnold Umformtechnik GmbH & Co.
www.arnold-fastening.com

Screws Fasten Ultra High-Strength Materials

Image: EJOT

MAXXtip screws combine a carbo-austempered shank with an ultra hard screw tip. This unique combination allows for direct fastening into ultra high-strength materials.

Due to the carbo-austempered microstructure in the load-bearing areas, the screws are insensitive to hydrogen embrittlement. Therefore, galvanic surfaces can be applied without tempering, leading to a thread flank hardness of at least 750 HV in the forming area.

When using EJOT’s SHEETtracs and Spiralform thread types, the screws can fasten ultra high-strength steel sheets with an ultimate tensile strength of at least 1,200 megapascals. And, when using EJOT’s Spiralform thread type, the screws can fasten GJS and GJL cast iron.

EJOT
www.ejot.com

Bolt Is Strong, but Lightweight

Image: Camcar Innovations

The Hexatrac Plus drive system was developed in response to customer demand for a lightweight fastener with a standard hex socket. Hexatrac Plus fits within the same envelope as a standard heavy hex head flange bolt, and it performs the same. However, it weighs 25 to 35 percent less. This weight reduction is achieved by the elimination of unnecessary material in the head.

Extensive testing was performed on the fastener to confirm that there are no concerns with head integrity. The drive is larger than the standard minimum across corners, which results in a tighter fit to a hex socket. The fastener is installed using standard hex sockets, no changes are required on the assembly line, including tightening parameters. It performs equally well with surface-drive sockets. Compared with a standard bolt, the drive system requires three times more torque required to yield the fastener, when using a standard hex or surface-drive socket.

The fastener is ideal for applications in which weight reduction is desirable and using a hex or surface drive socket is required. It’s also good for interior applications that currently use a standard heavy hex bolt, or exterior applications where the bolt is horizontal or the head is down.

The fastener is available in sizes M5 to M20.

Camcar Innovations
camcar.com

Fastener Combines Three Elements Into One

Image: Bossard Group

The ecosyn SEF is a multifunctional fastening element consisting of a hexagon nut, a flat washer, and a conical washer. Combining three fasteners into one part provides cost-saving benefits, including faster assembly times, reduced possibility of operational errors, and reduced bill of materials. The fastener was developed for the safe connection of electrically conductive contacts, especially in the high-voltage range, but it is also suitable for purely mechanical connections. It’s available with a large flat washer or a medium flat washer.

Bossard Group
www.bossard.com

Self-Drilling Screws Join Steel to Steel

Image: Tite-Fix Ltd.

Trunk-Tite is a self-drilling screw developed for steel-to-steel assembly applications, such as cable trunking, trays, lids, boxes and earth tags. Featuring a stick-fit square drive, the screw allows the assembler to drive the fastener in awkward, hard-to-reach places. The unique thread provides an ultra-strong attachment because it goes right to the head; it won’t work loose. The sharp drill point starts immediately for fast insertion. The flat pan head reduces the risk of overdriving.

Tite-Fix Ltd.
www.tite-fix.co.uk

Compression Limiters Reinforce Plastic Assemblies

Image: Spirol

Series CL6000 aluminum, precision-machined compression limiters reinforce high-stress joints in plastic assemblies where bolts are used to connect two components to each other. These lightweight, lead-free components protect the plastic from excessive compression by absorbing the load when the bolt is tightened to the recommended torque. This ensures the durability and reliability of the joint throughout the product’s lifespan.

The parts are machined from 2024-grade aluminum, which provides the best combination of strength, corrosion resistance, machineability and cost. They are 40 percent stronger and one-third the weight of the same compression limiter made from brass.

For applications that require extra bearing surface for the mating component, the CL6100 headed compression limiter has all of the features of the CL6000, with the addition of a head. In addition, for applications that require a galvanic alternative to aluminum, the same compression limiters can also be made from brass.

Available in a wide range of standard sizes, the components are made to precise tolerances for highly automated or molded-in assembly processes. Superior knurl formation and control result in more consistent and robust retention performance in post-mold assembly processes.

Spirol
www.spirol.com