In the celebrity world, the price of fame is that the public knows too much about the celebrity’s personal life. But in the assembly world, the price of well-known technology is that end users sometimes know too much about the benefits of one process and not enough about others.
This applies to blind rivets. Known to many in the industry, this process allows the assembler to fully install the rivet into the joint on only one side of the part or structure. Few people know about other important advantages of these rivets over threaded connections.
First, rivets must not be under-tightened, over-tightened, or loosened. They quickly, easily and economically connect metal, plastic, composite, wood, wood fiber and hollow tubular structures. Blind rivets also resist vibration, secure joints with short clip lengths, and eliminate 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 the English engineer Hamilton Neil Wylie. For 30 years, steel and aluminum rivets have been widely used in various industries in Europe and the United States.
Rivets are still popular in Europe, where some of the most interesting development and installation of rivets takes place. For example, Sarev SRL Unipersonale, located in Padua, Italy, manufactures various types of blind rivets, including Mass rivets, which consist of a copper body, a copper-plated mandrel, and brass quick-release terminals.
Due to these properties, rivets also conduct electricity and are widely used in the assembly of household appliances and electrical panels. It was developed by Sarev engineers on an individual order, depending on the number of cables to be connected and the type of material to be fixed.
Farther northeast, in Nizhny Novgorod, Russia, automotive turbocharger manufacturer CZ as uses tubular rivets to fasten identification plates to the compressor casing. Rivets are set using unidirectional mandrels at speeds up to 70 rpm. 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 wide variety of head types, materials and styles and are increasingly being used in product assembly in industries as diverse as aerospace, automotive, electronics, solar, jewelry and woodworking.
Blind riveting has many years of success, especially for 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 mobile phone electronic components.
A blind rivet is a fastener consisting of a hollow rivet body with a head and a solid mandrel (or rod). The body looks like a small tube, expanding at one end. The foramen or nucleus 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 position the jaws in the nose clip of the riveting tool to properly grip the mandrel. As the tool draws the head of the mandrel into the body of the rivet, the head expands the wall of the rivet radially to fill the hole. This stress also deforms the body of the rivet into a carrier head or ball at the end of the rivet, compressing 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 under vacuum into the assembly.
Equipment vendors point out that mandrel collection is particularly important for automotive and aerospace plants to limit the amount of waste. 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 rivet setting takes less than a second and requires the worker to pull the tool’s trigger only once. If the stroke of the tool is too short or its force is too low, it may take two trigger pulls to set a rivet that is too long.
“While blind riveting is a reliable fastening method, it has limitations,” said Craig Bonneville, Sales Director, GESIPA Riveting Division, SFS Group USA Inc. “The fasteners install quickly and are permanent. However, if the rivet needs to be removed and reworked, extra care must be taken to ensure that the rivet is removed correctly without damaging the application. Additionally, training assemblers on the tool helps ensure everything works as intended .works and the rivet is properly tightened in the application.”
GESIPA manufactures a wide range of assembly and installation tools, including the hand-operated GAV 8000 with electric drive. The basic ecological version does not have process control, while the electronic version offers this feature.
According to Bonville, both versions feature easy-to-use menus and function buttons on the HMI display. These tools are suitable for 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 managing Class C components,” explains Steven Sherman, Vice President of Engineering at the Industrial Rivet and Fastener Company (IRFC). , has been manufacturing all types of rivets since 1912. “In our experience, each time they are developed, they are converted 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 entering the rivet body, but not outside the rivet body and between materials. Sealed rivets are similar to standard rivets, except that the mandrel is completely closed for a watertight seal once installed.
Multi-clamp rivets compress when used with thin materials, reducing material droop at the back. Non-structural rivets destroy the mandrel near the head of the blind side, leaving a short mandrel in the body of the rivet with a partially filled core.
In contrast, structural rivets retain part of the mandrel after failure, providing high shear and tensile strength, as well as vibration resistance. These rivets can be used as an adjunct to structural adhesives, holding parts in place while the adhesive cures.
Blind rivets are defined by the material of the rivet and mandrel (in that order), and a match between the two is always recommended. Rivet materials include steel, stainless steel, aluminum, copper, brass and plastic. Industry materials include nylon rivets, used by Tier 1 automotive suppliers and OEMs to connect molded plastic parts, and non-ferrous monel and inconel alloy rivets, commonly used in the aerospace industry.
Standard rivet diameters range from 0.094″ to 0.375″. However, manufacturers in specific markets often require rivets up to 0.625 in. in diameter.
“Some types of rivets, such as our Quick Fastening line, are growing in popularity,” said Samir Kustovich, North American blind rivet product manager for Stanley Engineered Fastening. “Several versions are available, including NeoSpeed, Briv and Chobert, and they are installed using a unique repeating mandrel system. During installation, our tool pulls the mandrel through the rivet, causing axial and radial expansion. Provides clamping and simultaneous filling of the hole.”
The tool Kustovich is talking about is the Stanley SB25PT-05 cordless tool, which is backwards compatible with the previous hydropneumatic line it is based on. Both share the same interface design, making it easier for operators to transition from wired to wireless instruments.
Equally important, this tool allows you to quickly create repeatable connections with high accuracy. Standard features include a low-force one-finger trigger, an ergonomic softgrip for increased operator comfort, and LED illumination for a clear view of the job in progress.
For the past year or so, an American manufacturer has been using SB25PT-05 and NeoSpeed countersunk 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. What he especially likes is that the system allows quick reloading of the rivet and leaves no mandrel waste.
Each rivet has a specific grip range, indicating the thickest and thinnest combination of materials it can properly hold together. The wider the range, the greater the variation in thickness that can be used with a single rivet.
Blind rivet heads are rounded (standard), rounded and flat. Oversized dome heads are often used on softer materials to increase bearing area. Flat head with counterbore for flush mounting.
Composite materials such as plastic, fiberglass and plywood are fastened with rivets with different heading patterns. These rivets create a three-sided expansion on the back of the material (like an open flower petal) that distributes the clamping force.
The GESIPA Bulb-Tite rivet is one such rivet. It has a large diameter closing head that gently distributes pressure on sensitive and porous materials. Common applications in the automotive industry include the bonding of composite materials in the installation of speakers, door modules, body 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 note that the closed head is aesthetically pleasing and has a low profile. The rivet has a wide clamping range, which ensures a tight connection without rattling when subjected to vibration.
Rivet nuts and studs are also popular with manufacturers. One-piece support nuts have load-bearing internal threads and are used to secure detachable parts in materials that may be too thin to accommodate the threads. Nut studs combine rivet nuts and screws and are an effective alternative to weld studs. It can also be installed on pre-painted materials.
Blind rivet installation requires a tool that holds the rivet body in place while the mandrel is pulled into or through the rivet. Various manual and automated tools are available. The latter include hydropneumatics and battery electrics, which have become lighter, stronger and more ergonomic over the past 25 years.
Each tool comes with one or more nozzles to set a range of commonly used rivet sizes. Special attachments are available for special applications requiring additional narrow aisle access or turning functions.
Plier-like hand tools are usually only used in small volumes. Only rivets of smaller diameters and rivets made of softer materials can be installed. Hand tools, on the other hand, are lightweight and versatile.
Automated setting tools, including pistol riveters and linear or vertical riveters, provide greater pulling power and better withstand kickback when setting rivets. Pistol grip tools are designed for use on horizontal surfaces.
The linear riveter offers the possibility of vertical riveting and can be hung on a counterweight like a linear screwdriver. For high volume applications, riveting tools can be equipped with multiple heads to accommodate multiple fasteners at the same time. The tools can also be equipped with automatic rivet feeders that can hold thousands of rivets.
“About 98 percent of the tools used to set 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 complete range of blind riveting tools, including hand and lever operated, auto feed, pneumatic, battery and robotic lever end tools. The latest tools are independent of robots, customized 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 allow you to control the installation process of each rivet. Additional features include an LCD screen, a rivet counter, and a Wi-Fi card that wirelessly transmits data to the tool controller as well as the factory data center for control tracking and analysis.
Last fall, GESIPA introduced the PowerBird Pro Gold Edition, a 20kN cordless tool for heavy-duty rivets. It works with rivets from 2.4mm to 6.4mm in diameter and is powered by a Consortium System (CAS) rechargeable battery based on high-density lithium-ion or lithium-ion technology. The tool comes standard with a 2 Ah battery and a compact 4 Ah 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 go,” Bonneville explained. “End users also like 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 riveter is also battery operated. We can say that its intelligence comes from the on-board process monitoring system with an integrated touch screen. Once the force distance data is obtained 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. Kustovich claims it offers the quality and reliability of the original PB2500 tool, while also being cordless, further enhancing affordability, portability and productivity.
IRFC’s auto-feed blind rivet setting tool, called Kingset, feeds standard rivets (0.1875 in. diameter) from plastic tape in the loading tool. It weighs 5.5 pounds, has a 2 second cycle time and an 8 to 10 second reload time. All used mandrels are collected so as not to clutter up the work area with them.
An electronic component 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 align pre-drilled holes in metal and insert rivets, cutting cycle time by about 2 minutes per assembly. Shorter lead 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 Estate Engineering Journal and Milling Journal. Jim has a degree in English from DePaul University.
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Post time: Aug-30-2023
