Known to many in the manufacturing industry, this process allows assemblers to fully install rivets into a joint on only one side of a part or structure. Few people know about other important advantages of these Fixpal rivets over threaded connections.
First, rivets should not be undertightened, overtightened, or loosened. They quickly, easily and economically join metal, plastic, composites, wood, fiberboard and hollow tubular structures. Rivets also resist vibration, secure connections with a shorter clamping length, and eliminate the possibility of surface damage.
Interestingly, blind rivets are one of the oldest types of fasteners and have been around for over a century. POP rivets (so named because they “pop out” when installed) were patented in 1916 by British engineer Hamilton Neil Wylie. For 30 years, steel and aluminum blind rivets have been widely used in various industries in Europe and the USA.
Rivets continue to be popular in Europe, where some of the most interesting rivet developments and installations have occurred. For example, the Italian company Sarev SRL Unipersonale, based in Padua, produces various types of blind rivets, including Mass rivets, which consist of a copper body, a copper-clad mandrel and a brass quick-release clamp.
Due to these properties, rivets also conduct electricity and are widely used in the assembly of household appliances and electrical panels. It is custom designed by Sarev engineers taking into account the number of cables to be connected and the type of materials to be fixed.
Further northeast, in Nizhny Novgorod, Russia, automotive turbocharger manufacturer CZ AS uses tubular rivets to attach identification plates to the compressor housing. Rivets are installed using unidirectional mandrels at speeds up to 70 rpm. Initially, hammer screws were used to secure the boards, 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 an alternative to solid rivets that needed repair. More than 100 years later, rivets come in a wide variety of types, materials and head styles and are increasingly used in product assembly in industries as diverse as aerospace, automotive, electronics, solar, jewelry and woodworking.
Blind riveting has a long history of success, especially for large assemblies. Therefore, blind rivets are used in home appliances, heavy trucks, tractors, garage doors and prefabricated metal buildings. However, rivets are also increasingly used for the assembly of small products, such as electronic components of mobile phones.
A blind rivet is a fastener consisting of a hollow rivet body with a head and a solid mandrel (or shank). The body looks like a small tube that opens at one end. The opening 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, insert the body of the rivet. Then place the jaws into the rivet tool attachment to properly clamp the mandrel. As the tool pulls the mandrel head into the body of the rivet, the mandrel head causes the walls of the rivet to expand radially, filling the hole. This pulling force also deforms the body of the rivet into the load-bearing ball head at the end of the rivet, pressing the sheets together. Once the tool reaches a predetermined set force or tensile load, the mandrel breaks off and falls to the ground or is moved by vacuum into the assembly device.
Equipment suppliers note that mandrel collection is especially important in automotive and aerospace plants to limit waste. Small pieces of metal in cars can make rattling sounds that irritate drivers, and in airplanes they can cause serious structural damage.
Typical rivet installation takes less than a second and requires the worker to pull the trigger of the tool only once. Installing extra-long rivets may require two trigger pulls if the tool’s piston stroke is too short or its pull is too low.
“Although blind riveting is a reliable fastening method, it has limitations,” says Craig Bonneville, director of sales for GESIPA SFS Group USA Inc.’s riveting division. “The fastener installs quickly and is durable. However, if the rivet needs to be removed and recycled, extreme care must be taken to properly remove the rivet without damaging the product. Additionally, training the assembler on how to use the tool can help ensure everything works. works as intended and the rivets are properly tightened during service.”
GESIPA produces a wide range of assembly and installation tools, including the electric handheld model GAV 8000. The basic eco version does not have process monitoring, while the electronic version offers this feature.
Bonneville says both versions feature easy-to-use menus and function buttons on the HMI display. These tools are suitable for rivets with body lengths greater than 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, clamps and blind rivets to reduce the assembly and logistical complexities of component management,” explains Stephen Sherman, vice president of engineering at Industrial Rivet and Fastener Company (IRFC). , has been manufacturing various types of rivets since 1912. “In our experience, every time they are developed, they transform into new applications at a faster rate for a number of reasons.”
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 have a cupped end design that prevents water from penetrating through the body of the rivet, but not outside the body of the rivet and between materials. Sealing rivets are similar to standard rivets, except the mandrel is completely enclosed, creating a watertight seal when installed.
Multi-clip rivets compress when used with thin materials, leaving less material hanging off the back. Non-structural rivets destroy the mandrel near the head on the blind side, leaving a small section of mandrel in the body of the rivet with a partially filled core.
In contrast, structural rivets retain part of their mandrel after failure to provide high shear and tensile strength as well as resistance to vibration. These rivets can be used as a complement to structural adhesives, holding parts in place while the adhesive cures.
Blind rivets use rivet and mandrel materials (in that order) and it is always recommended to use these two materials. Rivet materials include steel, stainless steel, aluminum, copper, brass and plastic. Industry materials include nylon rivets, which are used by automotive suppliers and OEMs to join molded plastic parts, and non-ferrous Monel and Inconel rivets, which are often used in the aerospace industry.
Standard rivet diameters range from 0.094 to 0.375 inches. However, manufacturers in certain markets often require rivets up to 0.625 inch in diameter.
“Certain types of rivets, such as our Quick Fastening series, are growing in popularity,” notes Samir Kustovic, North America blind fastening product manager for Stanley Engineered Fastening. “Several versions are available, including NeoSpeed, Briv and Chobert, and are installed using a unique repeating mandrel system. During installation, our tool pulls the mandrel through the rivet, causing axial and radial expansion. Provides both clamping and hole filling.”
The tool Kustovich is talking about is the battery-powered tools Stanley SB25PT-05, which is backwards compatible with the previous series of hydropneumatic tools on which it is based. Both feature the same interface design, making it easier for operators to switch from corded to cordless tools.
Equally important, the tool quickly creates repeatable connections with high precision. Standard features include a low-force one-finger trigger, an ergonomic soft-grip handle for enhanced operator comfort, and LED illumination for a clear line of sight during operation.
For the last year or so, an American manufacturer has been assembling industrial stairs using SB25PT-05 and NeoSpeed rivets. During this time, the company installed millions of these rivets and preferred them to the solid rivets it had previously used. What he especially likes is that the system allows for quick rivet reloading and leaves no mandrel waste.
Each rivet has a specific grip range that indicates the thickest and thinnest combinations of materials it can properly fasten. The wider the range, the greater the variation in thickness that can be used with a single rivet.
Types of blind rivet heads include dome (standard), oversized dome, and flat head. Oversized dome heads are typically used on softer materials to increase the load-bearing area. The flat head has a countersunk hole for flush mounting.
Rivets with different settlement patterns are used to fasten parts made of composite materials such as plastic, fiberglass and plywood. These rivets create a three-way expansion on the back side of the material (like opening flaps) that distributes the clamping force.
Bulb-Tite rivet from GESIPA is one such rivet. It features a large diameter closed head that gently distributes pressure on sensitive and porous materials. Common applications in the automotive industry include bonding composite materials to install speakers, door modules, body and instrument panels, and seats.
The closed 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 like that the closed head is nice and discreet. This rivet has a wide clamping range, which provides a tight connection that does not rattle when exposed to vibration.
Rivet nuts and studs are also popular with manufacturers. Solid support nuts have load-bearing internal threads and are used to install removable parts made from materials that may be too thin to accommodate threads. Nut studs combine rivet nuts and screws and are an effective alternative to weld studs. It can also be installed on pre-coated materials.
Installing a blind rivet requires a tool to hold the body of the rivet in place while the mandrel is pulled into or through the rivet. A variety of manual and automated tools are available. The latter include hydropneumatics and battery electrics, which have become lighter, more powerful and more ergonomic over the past 25 years.
Each tool is equipped with one or more sockets to accommodate the most commonly used rivet size ranges. Special attachments are available for specific applications that require additional access to narrow channels or rotation functionality.
Hand tools, similar to pliers, are usually only intended for small jobs. Only rivets of smaller diameter and rivets made of softer materials can be installed. Hand tools, on the other hand, are lightweight and versatile.
Automated installation tools, including pistol rivet guns and linear or vertical rivet machines, provide greater pulling force and are better able to withstand the recoil forces encountered when setting rivets. Pistol grip tools are designed for use on a horizontal surface.
Linear riveting machines offer vertical riveting capabilities and can be suspended from a counterweight, like a linear screwdriver. For high-volume applications, riveting tools can be equipped with multiple heads to install multiple fasteners simultaneously. The tools can also be equipped with automatic feeders that can hold thousands of rivets.
“About 98 percent of the tools used to install blind rivets in assembly are hand-held,” Sherman says. “This is because hand tools are the easiest way to join multiple layers of metal and plastic. Manufacturers use in-line tools and robotic tools for installation, but only when the application requires it.”
IRFC offers a full range of blind rivet setting tools, including hand-held, automatic-feed lever tools, pneumatic, cordless and robotic end-of-lever tools. The latter tool is robot independent and is developed by IRFC engineers for each application.
Less than two years ago, IRFC released the third generation of Freeset cordless tools. Force and distance sensors in the tool allow you to monitor the installation process of each rivet. Other features include an LCD screen, rivet counter, and a Wi-Fi card that wirelessly sends data to the tool controller and factory data center for monitoring and control analysis.
Last fall, GESIPA released the PowerBird Pro Gold Edition, a cordless tool with 20 kN holding force for heavy-duty rivets. It can handle rivets from 2.4mm to 6.4mm in diameter and is powered by an Alliance System (CAS) battery based on lithium-ion or high-density lithium-ion technology. The tool comes standard with a 2 amp-hour battery, and 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 in one charge,” explains Bonneville. “End users also like the CAS battery because it works with all of our PowerBird rivet tools, and many customers have more than one type of PowerBird tool.”
The Stanley PB2500 SMART rivet gun is also battery operated. We can say that its intelligence comes from the on-board process monitoring system with a built-in touch screen. Immediately after receiving the force distance data for each rivet installation, the system compares it with a “good” force distance curve. The operator is then notified whether 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. According to Kustovich, it has the quality and reliability of the original PB2500 tool and is cordless, further enhancing accessibility, mobility and productivity.
IRFC’s auto-feed blind rivet setting tool, called Kingset, feeds standard rivets (0.1875-inch diameter) from a plastic strip loaded into the tool. It weighs 5.5 pounds, has a cycle time of 2 seconds and a recycle time of 8 to 10 seconds. All used mandrels are collected so as not to clutter the work area with them.
The electronic components manufacturer has been using Kingset to assemble sheet metal chassis for three years. Sherman said the company likes that the tool simplifies the process and reduces operator movement. Operators line up pre-drilled holes in the metal and insert rivets, cutting cycle time by approximately 2 minutes per assembly. The shorter cycle time allows the company to produce about 600,000 units per year.
Post time: May-14-2024
