In celebrity circles, the price of fame is that the public knows too much about the celebrity’s private life. But in the world of assembly, the price of well-known technology is that end users sometimes know too much about one process benefit and not enough about others.
This applies to blind rivets. Known to many in the industry, this process allows the assembler to fully install a rivet into a joint on only one side of a part or structure. Few people know about other important advantages of these rivets over threaded fasteners.
First, rivets must not be tightened, overtightened, or loosened. They connect metal, plastic, composite, wood, fiberboard and hollow tubular structures quickly, easily and economically. Blind rivets also resist vibration, provide secure connections with short clamp lengths, and eliminate the possibility of surface damage.
Interestingly, pop rivets are one of the oldest types of fasteners, having been around for over a century. The POP rivet (so named because it “pops out” when installed) was patented in 1916 by British engineer Hamilton Neil Wylie. For 30 years, steel and aluminum rivets have been widely used in various industries in Europe and the USA.
Blind rivets are still popular in Europe, where the most interesting rivets are developed and installed. For example, Sarev SRL Unipersonale, located in Padua, Italy, manufactures various types of blind rivets, including bulk rivets, consisting of a copper body, a copper-clad shank and a brass stud.
Because of these properties, rivets also conduct electricity and are often used to assemble appliances and electrical panels. It is custom designed by Sarev engineers according to the number of cables to be connected and the type of material to be fixed in the application.
Farther northeast, in Nizhniy Novgorod, Russia, automotive turbocharger manufacturer CZ as uses tubular blind rivets to fasten identification plates to their compressor housings. Rivets are set using a single-start mandrel at speeds up to 70 per minute. Initially, screws with a hammer were used to hold the boards in place, but the hammer often damaged the screw heads, and the installed screws looked terrible.
When blind rivets were first introduced, they were made from aluminum and were used as a replacement for solid rivets that needed repair. More than 100 years later, rivets come in a variety of head types, materials and styles, and are increasingly being used to assemble products in industries such as aerospace, automotive, electronics, solar, jewelry and woodworking.
Blind rivets have many years of success, especially in large assemblies. As a result, blind rivets are used in appliances, heavy trucks, tractors, garage doors, and prefabricated metal buildings. However, rivets are also increasingly being used to assemble small items such as electronic components in mobile phones.
A blind rivet is a two-piece rivet consisting of a hollow rivet body with a head and a solid mandrel (or shank). The body looks like a small tube with one open end. The hole or core usually extends along the length of the body. The mandrel protrudes from the core and looks like a nail or wire.
After drilling or punching holes in the parts to be joined, the body of the rivet is inserted. Then place the jaws on the nose of the rivet tool to properly grip the mandrel. As the tool pulls the mandrel head into the rivet body, the mandrel head radially expands the rivet wall to fill the hole. This pull also deforms the body of the rivet into a carrier head or ball at the end of the rivet that holds the sheets together. As soon as the tool reaches a predetermined set force or tensile load, the mandrel breaks off and falls to the ground or moves under vacuum into a collecting device.
Equipment suppliers point out that mandrel collection is especially important for auto and aerospace factories to limit the amount of trash. Small pieces of loose metal in a car can rattle and annoy drivers, and in an airplane they can cause serious structural damage.
A typical blind rivet installation takes less than a second and workers only need to pull the tool’s trigger once. Extra long rivets may require two trigger pulls if the tool stroke is too short or the force is too low.
“While blind riveting is a reliable fastening method, it does have limitations,” said Craig Bonnville, Sales Director, SFS Group USA Inc. Rivets. GESIPA. properly without damaging the application. Also, teaching the assembler how to use the tool helps ensure that everything is working properly and that the rivet is properly installed in the application.”
GESIPA manufactures a wide range of assembly and installation tools, including the portable GAV 8000 with electric drive. There is no process control in the basic ecological version, but this function is available in the electronic version.
Bonneville says both versions feature easy-to-use menus and function buttons on the HMI display. These tools can handle rivets with body lengths over 30mm and flange diameters up to 11.4mm. All used mandrels are drained through a hose connected to a collection container.
“Automotive engineers are often encouraged to design fasteners, clips and blind rivets to simplify assembly and logistics when working with Class C components,” explains Steven Sherman, vice president of engineering at Industrial Rivet & Fastener Co. (IRFC). , has been producing all types of rivets since 1912. “In our experience, for a variety of reasons, they are developed much more frequently and more often developed for new applications.”
Blind rivets come in a variety of types, materials, diameters, grip ranges, and head styles. Standard split rivets are the most common and cheapest, but they are neither waterproof nor durable.
Closed end rivets are cupped to prevent water from entering the inside of the body of the rivet, but not outside the body and between the materials. Sealed rivets are similar to standard rivets, except that the mandrel is completely closed, creating a watertight seal when installed.
Multi-shank rivets compress when used on thin materials, reducing material droop on the back side. Non-structural rivets broke the mandrel near the head of the blind side, leaving a short section of the mandrel in the body of the rivet with a partially filled core.
In contrast, structural rivets retain part of the mandrel after failure to provide high shear and tensile strength as well as vibration resistance. These rivets can be used in addition to structural adhesives, securing components while the adhesive is curing.
Blind rivets are defined by the material of the rivet and the stem (in that order), and it is always recommended to combine the two materials. Rivet materials include steel, stainless steel, aluminum, copper, brass and plastic. Specialty materials include nylon rivets, which are used by Tier 1 vehicle suppliers and OEMs to join molded plastic parts, and Monel and Inconel non-ferrous alloy rivets, which are often used in the aerospace industry.
Standard rivet diameters range from 0.094″ to 0.375″. However, manufacturers in certain markets often require rivets up to 0.625 in. in diameter.
“Some types of rivets, such as our Speed Fastening series, are growing in popularity,” said Samir Kustovich, North American Blind Fastening Product Manager for Stanley Engineered Fastening. “Several versions, including NeoSpeed, Briv and Chobert, are available and set using a unique repetitive mandrel system. During setting, our tool pulls the mandrel through the rivet, causing axial and radial expansion while securing and filling the hole.”
The tool Custovic is talking about is a battery powered Stanley SB25PT-05 that is backwards compatible with the previous hydropneumatic series it is based on. Both share the same interface design, making it easy for operators to migrate from wired to wireless instruments.
Just as important, this tool can quickly create reproducible connections with high precision. Standard features include a low-force one-finger trigger, an ergonomic softgrip for operator comfort, and LED illumination for a clear view of the application.
For the past year, the American manufacturer has been using SB25PT-05 and NeoSpeed blind rivets to assemble industrial ladders. During this time, the company has installed millions of these rivets and prefers them over the solid rivets it has used in the past. I especially like that the system allows you to quickly reload the rivets and does not leave mandrel waste.
Each blind rivet has a specific clamping range indicating the thickest and thinnest combination of materials it can properly hold together. The larger the range, the greater the change in thickness can be used with a single rivet.
Blind rivet head styles include rounded (standard), oversized rounded, and flat. Oversized domes are often used with softer materials to increase the bearing area. Flat head with countersunk head for concealed mounting.
Rivets with different thickening patterns are used to fasten parts made of composite materials, such as plastic, fiberglass and plywood. These rivets create a three-sided expansion (like an open flower petal) on the back of the material, so the clamping force is distributed.
Bulb-Tite from GESIPA is one such rivet. It has a large diameter closing head for gentle pressure distribution on sensitive and porous materials. Common automotive applications include the bonding of composite materials in the installation of speakers, door modules, bodywork and instrument panels, and seats.
The closing head prevents the rivet from being pulled out of the application, and the locking mandrel holds the connection securely even under high loads. End users also appreciate the closed head aesthetic and low profile. Rivets have a wide grip range and create a tight joint that does not rattle when vibrated.
Also popular among manufacturers are rivet nuts and racks. One-piece rivet nuts have load-bearing internal threads and are used to connect detachable parts whose material may be too thin to accommodate the threads. Nut studs combine rivet nuts and screws and are an effective alternative to welded studs. It can also be installed in pre-painted materials.
Blind rivet installation requires a tool that holds the body in place while the mandrel is pulled into or through the rivet. A wide range of manual and automatic tools are available. The latter include hydropneumatics and wireless electrics, which have become lighter, stronger and more ergonomic over the past 25 years.
Each tool comes with one or more nozzles for setting the most commonly used rivet sizes. Special tips are available for specific applications requiring additional narrow aisle access or swivel capabilities.
Hand tools such as pliers are usually used in small volumes. They can only install smaller diameter rivets and rivets made from softer materials. On the other hand, hand tools are lightweight and versatile.
Automated tools, including pistol rivets and recessed or vertical rivets, provide greater pulling force and better resist the kickback that occurs when setting rivets. Pistol grip tools are designed for use on horizontal surfaces.
The built-in riveter offers a vertical rivet option that hangs on a counterweight like a built-in screwdriver. For high-volume work, riveting tools can be equipped with multiple heads to accommodate multiple fasteners at the same time. The tool can also be equipped with an auto feeder that can hold thousands of rivets.
“About 98 percent of the tools used to set blind rivets in assembly are manual,” Sherman says. “This is because hand tools are the easiest way to join multiple layers of metal and plastic. Manufacturers also use built-in and robotic tools, but only when needed.”
IRFC offers a complete range of blind riveting tools including hand and lever tools, auto-feed tools, pneumatic tools, battery powered tools and robotic hand end tools. The last tool is independent of robots, individual and developed by IRFC engineers for each application.
Less than two years ago, IRFC introduced the third generation of Freeset cordless tools. Force and distance sensors in the tool monitor every rivet setting process. Additional features include an LCD screen, a rivet counter, and a Wi-Fi card to wirelessly send data to the tool controller, as well as to the factory data center for control tracking and analysis.
Last fall, GESIPA introduced the PowerBird Pro Gold Edition cordless tool with 20 kN setting force for heavy-duty rivets. It works with rivets from 2.4mm to 6.4mm in diameter and is powered by a Consortium System (CAS) battery based on Li-Ion or Li-Ion High Density technology. A 2 amp-hour battery is standard with the tool, while a compact 4 amp-hour battery is available as an accessory.
“In addition to being more ergonomic, this tool allows assemblers to set a large number of rivets on a single battery charge,” Bonnville explained. “End users also love the CAS battery because it can be used with all of our PowerBird riveting tools and many customers have more than one type of PowerBird tool.”
The Stanley PB2500 SMART rivet gun also runs on batteries. Its intelligence, so to speak, comes from an onboard process monitoring system with an integrated touch screen. Immediately after receiving the force-distance data for each rivet setting, the system compares it to a “good” force-distance curve. Then inform the operator if the installed rivets are in order. The tool can store up to 500,000 tuning results for later analysis.
The tool also supports Wi-Fi and Bluetooth and is designed for blind riveting on the assembly line or in remote locations. Custovic says it offers the quality and reliability of the original PB2500 tool and is cordless, further enhancing worker accessibility, mobility and productivity.
The IRFC auto-feed blind rivet setting tool, called the Kingset, feeds standard rivets (0.1875 in. diameter) from a plastic strip loaded into the tool. It weighs 5.5 pounds, has a 2 second cycle time and an 8 to 10 second reload time. Collect all used mandrels so they don’t clutter up your work area.
For three years, an electronic component manufacturer has been using Kingset to assemble sheet metal cases. Sherman says the company likes that the tool simplifies the process and reduces operator movement. Operators insert rivets while aligning pre-drilled holes in the metal, reducing cycle time by about 2 minutes per assembly. Short cycle times allow the company to produce around 600,000 units per year.
Jim is a Senior Editor at ASSEMBLY with over 30 years of editorial experience. Prior to joining ASSEMBLY, Camillo was editor of PM Engineer, Association for Equipment Engineering Journal and Milling Journal. Jim has a degree in English from DePaul University.
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