Rivets are some of the most important fasteners available to engineers. These simple devices are found in all sorts of products, from aerospace panels to leather belts. Although rivets are similar in the way they permanently join materials, their structures, materials, and installation methods vary widely depending on the application. They are used to securely attach two pieces of material and create a long-lasting mechanical joint.
So what is the purpose of a rivet, and what are the different rivets available to engineers? This article explains how rivets work, what they are made from, and how to choose the right type for your project.
Throughout the article, we draw on 3ERP’s 15+ years of experience in sheet metal fabrication, CNC machining, and other manufacturing processes that require careful assembly of components using rivets.
What Is a Rivet and How Does It Work?
A rivet is a type of permanent mechanical fastener used to join two or more pieces of material. Consisting of a head and shaft, a rivet is inserted through aligned holes before its tail end is deformed to create a second head. This deformation creates a durable “lock,” preventing the rivet from coming undone.
In modern manufacturing, rivets are the most common solution for joining thin sheets of metal, plastics, and composites where welding or threaded fasteners are not ideal.
Definition of a Rivet
The McGraw-Hill Dictionary of Engineering offers the following definitions of “rivet” and “riveting”:
- “Rivet” definition: A short rod with a head formed on one end; it is inserted through aligned holes in parts to be joined, and the protruding end is pressed or hammered to form a second head.
- “Riveting” definition: The permanent joining of two or more machine parts or structural members, usually plates, by means of rivets.
How Do Rivets Work?
Rivets work by permanently joining two pieces of material together through the deformation of one end of the rivet. This deformation is sometimes called rivet upsetting or bucking.
The rivet is inserted through two or more aligned holes before its tail is squashed, split, or bent so it spreads out and forms a second head. The spread-out second head is now too wide to slip back through the hole, so the materials are securely attached.
The exact method of deformation varies by rivet type and process. Some methods use a rivet gun or press, while others use a hammer.
Parts of a Rivet
A rivet consists of different sections. Knowing rivet terminology is important when discussing different rivet types and installation processes. A solid rivet consists of several key parts:
- Head or Factory Head: The pre-formed wider end of the rivet that stops it being pulled through the holes.
- Shank or Body: The smooth and cylindrical shaft that passes through the aligned holes.
- Tail: The narrower end of the rivet that gets deformed during the riveting processes to form a second head and finish the joint.
- Shop Head or Bucktail: The second head formed by the deformation of the tail; does not exist until installation is complete.
- Mandrel: Found in blind rivets; an internal pin that gets pulled by a rivet gun to buckle the tail and form a second head.
Advantages of Using Rivets
Rivets offer many benefits over other fastener types, their main advantages being their durability and ease of installation.
- Permanence: Rivets create solid, permanent connections between materials that do not loosen from vibration, making them suitable for dynamic loads.
- Shear strength: Rivets handle sideways forces well, making them ideal for structural joints.
- Fast installation: Rivets are quick to install, especially with specialist tools like rivet guns.
- One-side access: Blind rivets are incredibly useful as they can be installed with access to just one side of the hole; this gives them an advantage over fasteners like nuts and bolts, which require access to both sides.
- Versatility: Rivets can be used to join materials that differ in terms of their composition and thickness; even very thin materials are unlikely to deform.
- Affordable: Riveting is cheaper than advanced joining techniques like welding or certain complex bolting systems, requiring generally affordable and easy-to-use equipment.
- No heat distortion: Unlike welding, riveting does not require heat, preventing potential deformation of the workpieces.
- Ease of inspection: Rivets can be easily inspected for signs of wear or damage, and they can be fairly easily replaced.
Disadvantages of Riveted Connections
Although rivet benefits are many and varied, there are few rivet disadvantages to keep in mind when selecting a joining method.
- Bulkiness: Compared to joining methods like welding and bolting, rivets are fairly bulky and heavy.
- Visibility: Compared to welding, rivets have a greater visual impact on the final part that may be undesirable.
- Water-tightness: Rivets are not inherently leak-proof and may need additional sealants for certain applications.
- Corrosion risk: Galvanic corrosion is a risk if the rivet and workpieces are made from different metals.
- Permanence: A benefit in many situations, the permanence of rivets can make them less advantageous in parts that require disassembly, such as furniture.
Materials Used for Rivets
Several rivet materials are available, including steel, aluminum, and copper. The main pros and cons of rivet metals and plastics are explained below.
Steel Rivets
Steel rivets excel in terms of their high shear strength and tensile strength. Many industrial versions are made from high carbon steel. They can be found in structural steelwork, bridges, heavy machinery, and other steel-based assemblies. One disadvantage of steel rivets is their corrosion susceptibility.
Stainless Steel Rivets
Stainless steel rivets balance strength with corrosion resistance, making them suitable for applications in the marine industry, as well as food processing and various outdoor applications. One limitation of stainless steel rivets is the higher setting force required.
Aluminum Rivets
Aluminum rivets are lightweight, corrosion resistant, and relatively easy to set. You can find them in various sheet metal parts, lightweight aerospace structures, and electronic devices. They are less strong than steel rivets.
Copper and Brass Rivets
Copper rivets—and rivets made from copper alloys like brass—are soft, ductile, and highly conductive. They may be used in electrical grounding, roofing, and leather items like belts, footwear, and wallets. Disadvantages include lower strength and susceptibility to corrosion or patina.
Plastic Rivets
The most lightweight rivets are plastic rivets. Non-conductive and corrosion resistant, plastic rivets can be used for very light loads and cosmetic assemblies. However, they are weak and unsuitable for structural joints.
Main Types of Rivets
Rivets vary by material, but they can also be classified by their physical mechanism. For example, some rivet designs are deformed by squashing, while others are split. Some rivets can be installed from just one side of the hole.
Solid Rivets
Solid rivets are the oldest rivet type, dating back to Ancient Egypt. They are also the strongest and are therefore used in applications where reliability is important. These rivets have a solid metal shaft with a pre-formed head. Once set into the aligned holes, the tail is deformed to create a second head, usually with a tool like a hammer, rivet gun, or press. Access to both sides is required.
Blind Rivets (Pop Rivets)
Blind rivets—sometimes called “pop” rivets in reference to the original manufacturer of these rivet types—are made for situations where only one side of the hole can be accessed. The standard blind rivets consist of a hollow rivet body and a mandrel. The mandrel is pulled up, causing the rivet body on the blind side of the hole to expand. The mandrel then snaps off at a pre-made break point.
Semi-Tubular Rivets
Semi-tubular rivets resemble solid rivets but have a partially hollow rivet shank. This allows for lower forces to be applied when deforming the tail, which rolls outward to form the second head—like rolling the cuff of a sock back on itself. Semi-tubular rivets are ideal for high-speed manufacturing, offering a good balance of strength, cost, and installation speed.
Split Rivets (Bifurcated Rivets)
Split rivets do not particularly resemble the rivets described above. These rivets have a slotted shank that splits into two legs during installation, much like a brad or brass fastener used to secure papers. As the rivet is installed, its two legs spread apart and grip the material. They are easy to install, even on soft materials like wood, but they provide less strength and vibration resistance compared to the rivet types described above.
Flush Rivets (Countersunk Rivets)
Flush rivets are designed to sit flush with the surface of the material and therefore typically have a flat head. For a flush sitting to be possible, the hole must be countersunk. Flush rivets are aerodynamic and smooth and are therefore important in industries like aerospace and automotive. However, they are typically less strong than rivets with a protruding head.
Self-Piercing Rivets
Self-piercing rivets are designed to join materials without pre-drilled holes. A special rivet gun is used to force the rivet through the first sheet of material and into (but not entirely through) the second sheet, forming a solid joint with good fatigue resistance. Self-piercing rivets are ideal for high-speed, automated manufacturing and are suited to the joining of dissimilar materials.
Drive Rivets
A drive rivet is a type of blind rivet. It contains a short mandrel protruding from the head that is hammered, causing the tail end to flare out on the blind side. The main advantages of drive rivets are simplicity, speed, and low cost. They can also be used with a wide range of materials and require no equipment besides a hammer. However, the resulting clamping force is low compared to other rivet types.
Rivet Type Comparison Table
| Rivet Type | Deformation | Equipment | Uses | Strength |
| Solid | Tail plastically upset to form second head | Rivet gun, hammer, or press | Aircraft structures, bridges, pressure vessels | Very high |
| Blind (Pop) | Body expands as mandrel pulled, then mandrel snaps | Blind rivet tool | Enclosures, appliances, any part requiring one-side access | Low–medium |
| Semi-Tubular | Hollow end rolls outward to form second head | Press or roll-set tool | Hinges, electronics, automotive parts | Medium |
| Split (Bifurcated) | Slotted legs separate and spread | Hammer or simple press | Wood, leather, plastics, light assemblies | Low |
| Flush (Countersunk) | Tail upset while head sits in countersink | Rivet gun | Aerospace skins, body panels, visible surfaces | High |
| Self-Piercing | Rivet pierces top sheet and flares within lower sheet | Hydraulic or servo press | Automotive body structures, mixed materials | High |
| Drive | Central pin driven in to expand tail | Hammer or arbor press | Signs, nameplates, trim, light fixtures | Low |
How to Choose the Right Rivet Type
The following considerations should be taken into account when choosing a rivet type. Alternatively, an assembly expert like 3ERP can guide you to the right decision.
- Material requirements: Matching the rivet and workpiece material can prevent galvanic corrosion, while different rivet materials have different benefits.
- Load requirements: Solid rivets provide very high strength and are suited to higher loads, while other rivet types balance strength with other characteristics.
- Accessibility: Different types of blind rivets are suitable when access to the blind side of the joint is impossible.
- Head style: While domed heads are standard, flange heads and countersunk heads are also possible.
- Assembly speed: Some riveting methods—typically those that use pneumatic rather than manual tools—can be performed at high speeds and are suitable for mass production.
- Aesthetics: Different rivets have different appearances when finished, while certain rivet materials such as copper may be more cosmetically desirable.
Conclusion
This rivet guide has characterized the different types of rivets, looking at the main rivet designs, rivet materials, and suitable rivet applications. These permanent mechanical fasteners are easy to install, incredibly resilient, and can be used on a wide range of base materials.
For your next project that requires high-quality assembly of multiple sheets using rivets, request a quote from 3ERP.
FAQs
What is the most common type of rivet used in sheet metal?
The most common types of sheet metal rivets are blind rivets—ideal for enclosures and other items where the internal sections are not accessible—and various types of solid rivets, which offer superior strength.
How strong are rivets?
Rivet strength is high in the shear—they can withstand high forces perpendicular to the rivet shaft. However, fasteners like nuts and bolts provide a higher level of tensile strength with their greater clamping forces.
What materials are best for outdoor rivets?
Corrosion-resistant rivet materials include stainless steel rivets, aluminum rivets, and copper rivets, all of which are widely used for outdoor applications. However, compatibility with the base material must be considered.
Can rivets be removed or replaced?
Yes, rivets can be removed and replaced, though the process is more labor-intensive than removing or replacing nuts and bolts or other impermanent fasteners. Methods include drilling, chiseling, and the use of specialized rivet busting tools. These are used for major projects like bridge restoration.
What tools are required for installing rivets?
Rivet usage and installation requires different tools depending on the rivet type. Some common pieces of equipment include:
- Rivet gun or riveter: Handheld tool that clamps and pulls mandrel to set the rivet. Can be battery-powered, pneumatic, etc.
- Rivet press: Another riveting tool used to apply squeezing force to set a rivet. Can be manual, pneumatic, etc.
- Hammer: Non-specialist tool used for manually setting solid rivets, drive rivets, etc.
- Bucking bar: Used to support rivet tail while hammering head.
- Drill: Used to make holes through base materials.
How do you install solid rivets?
Solid rivets can be installed with a simple hammer and bucking bar or with a specialist rivet gun and bucking bar.
