In the celebrity world, the price of fame is that the public knows too much about the star’s private life. But in the world of assembly, 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 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 cannot be under-tightened, over-tightened, 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, based in Padua, Italy, manufactures various types of blind rivets, including bulk rivets, consisting of a copper body, a copper-clad shank, and brass quick-acting tips.
Due to these properties, rivets also conduct electricity and are commonly used in the assembly of household 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 Nizhny Novgorod, Russia, automotive turbocharger manufacturer CZ as uses tubular blind rivets to attach identification plates to the product’s compressor housing. Rivets are set through unidirectional mandrels 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 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 rivets have 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 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, expanding at one end. The hole or pith usually runs the entire 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 in the nose clip of the rivet tool to properly clamp 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. 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 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 the blind rivet is a reliable fastening method, it has limitations,” said Craig Bonnville, Sales Director, GESIPA Rivet Division, SFS Group USA Inc. “The fasteners install quickly and permanently. 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. Also, training assemblers on how to use the tool helps ensure everything is working properly. . and the rivet is properly tightened in the application.”
GESIPA manufactures a wide range of assembly and installation tools, including the portable 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 have 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 managing Class C components,” explains Steven Sherman, Vice President of Engineering at the Industrial Rivet and Fastener Company (IRFC). , has been producing rivets of all types since 1912. “In our experience, each time they are developed, they are developed for new applications at a faster rate for a number of reasons.”
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 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 on thin materials, reducing material droop on the back side. Non-structural rivets break 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 breaking to provide high shear and tensile strength, as well as vibration resistance. These rivets can be used in addition to structural adhesives, holding parts in place while the adhesive cures.
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. Industry materials include nylon rivets, which are used by Tier 1 vehicle suppliers and OEMs to join molded plastic parts, and non-ferrous alloy monel and inconel 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 Quick Fastening range, are becoming more popular,” says Samir Kustovich, North America Blind Fastening Manager, Stanley Engineered Fastening. “Several versions are available, including NeoSpeed, Briv and Chobert, which are set using a unique repetitive mandrel system. During setting, our tool pulls the mandrel through the rivet, causing axial and radial expansion. Clamps and fills the hole at the same time.”
The tool Kustovich is talking about is a battery powered Stanley SB25PT-05 that is backwards compatible with the previous hydropneumatic line 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 increased operator comfort, and LED illumination for line-of-sight 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. What I especially like is that the system allows fast reloading of rivets and leaves no mandrel waste.
Each blind 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 can be used with a single rivet.
Blind rivet head styles include rounded (standard), oversized rounded, and flat. Large size dome heads are often used on softer materials to increase the bearing area. Flat head with countersink for flush fit.
Rivets with different heading patterns are used to fasten parts made of composite materials such as plastic, fiberglass and plywood. These rivets create a three-sided expansion on the back of the material (like an open flower petal) that distributes the clamping force.
Bulb-Tite from GESIPA is one such rivet. It has a large diameter capping head that distributes pressure gently over 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 that the closed head is aesthetically pleasing and has a low profile. The rivet has a wide clamping range to form a tight joint without rattling when subjected to vibration.
Rivet nuts and stud nuts are also popular with manufacturers. Solid lock nuts have internal load-bearing threads and are used to mount detachable parts in materials that may be too thin to accommodate the threads. Nut studs combine rivet nuts with screws and are an effective alternative to weld studs. It can also be installed in pre-painted materials.
Blind rivet installation requires a tool that holds the body of the rivet 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 for setting the most commonly used rivet sizes. Special attachments are available for special applications requiring additional narrow aisle access or turning functions.
Hand-held, plier-like hand tools are typically used for smaller jobs. They can only install smaller diameter rivets and rivets made from softer materials. On the other hand, hand tools are lightweight and versatile.
Automated riveting tools, including pistol riveters and linear or vertical riveters, provide greater pulling force and better resist kickback forces when setting rivets. Pistol grip tools are designed for use on horizontal surfaces.
The built-in riveter offers the possibility of vertical riveting and can be suspended from the 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 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 manual,” Sherman says. “This is because hand tools are the easiest way to join multiple layers of metal and plastic. Manufacturers use inline tools and robotic tools for installation, but only when required for a particular application.”
IRFC offers a complete range of blind riveting tools including hand and lever operated tools, auto feed tools, pneumatic tools, battery powered tools and robotic hand 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 sends data wirelessly 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 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. 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, the tool allows assemblers to set a large number of rivets in a single charge,” Bonnville 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. 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, as well as wireless connectivity, further improving worker accessibility, mobility and productivity.
The IRFC auto-feed blind rivet setting tool, called the Kingset, feeds standard rivets (0.1875″ diameter) from the plastic strip into 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 that they do not clutter up the work area.
An electronic component manufacturer has been using Kingset to assemble sheet metal cases 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 metal by inserting 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 Equipment Engineering Journal and Milling Journal. Jim has a degree in English from DePaul University.
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Post time: Aug-21-2023
