Rivets: An Important Fastening Technology with Numerous Applications(low alloy steel Riva)
- source:LONTL CNC Machining
What are Rivets?
A rivet is a mechanical fastener that consists of two main parts - a cylindrical shaft and a head. The shaft is inserted into a hole through the materials being joined. The head is larger than the hole and after insertion, the blind end of the shaft is upset, or smashed, to form a second head. This creates permanent deformation, forming a rivet in place that holds the materials together.
Rivets are usually made of metal, including aluminum, steel, copper, stainless steel, and monel. The choice of material depends on the application and necessary strength, weight, and corrosion resistance. Heat treating is often used to increase rivet strength. The head shapes can be round, brazier, flat, countersunk, and more.
Key Advantages of Rivets
There are several reasons rivets are so widely used:
- Cost effective - Rivets are inexpensive to manufacture at high volumes, keeping costs low.
- Quick installation - Hand, pneumatic, and hydraulic riveters allow fast pop riveting for high productivity.
- Material flexibility - Rivets can join dissimilar materials like metal stacks. Only one side needs access.
- Vibration resistant - Rivet heads mechanically lock materials even under loads and vibration.
- Reliable - Properly installed rivets produce consistent and reliable joints. Testing verifies optimum grip length.
- Scalable strength - Rivet strength is tailored for each application by adjusting alloy and diameter.
These advantages make rivets ideal for mass production across many industries.
Common Rivet Types and Uses
The main categories of rivets include solid rivets, blind rivets, drive rivets, and specialty rivets. Each has design variations suited to specific applications:
- Round head rivets - Most common type with a semi-circular head. Used for general applications.
- Countersunk head - Flush rivets with a flat, countersunk head. Used in aerospace for smooth surfaces.
- Brazier head - Low profile rounded head. Used in thin sheet joining. Minimal hardware projection.
- Large flange head - Flat, oversized rivet head. Provides extra load distribution. Used in high shear applications.
- Pop rivets - Tubular rivets installed via a stem tool. Common in manufacturing and DIY.
- Break-mandrel rivets - Similar to pop rivets but with a break-away mandrel. Used in aerospace.
- Split rivets - Separates into two halves during installation. Enables headless rivet applications.
- Drive screws - Hardened pins that cut threads into materials during installation. Vibration resistant.
- Self-piercing rivets - Pierces and clinches material when driven. No hole pre-drilling needed.
- Structural rivets - Extra large rivets up to 1 inch diameter. Used for critical load transfer in civil structures.
- Blind threaded inserts - Installed into materials to provide female screw threads. Allow removable fasteners.
- Tubular rivets - Hollow and often flared. Used in custom applications.
Key Industries that Rely on Rivets
The versatility and reliability of rivets make them vital across industries:
Aerospace - Aircraft construction extensively uses specialty rivets, like cherrying and countersunk rivets. Riveting allows complex airframe assembly while minimizing weight.
Construction - Steel structures including bridges and buildings rely on large structural rivets for beam connections that handle wind, seismic, and gravity loads.
Manufacturing - Rivets provide durable fastening for factory equipment, vehicles, electronics, appliances, and more. Blind rivets enable automated assembly.
Transportation - Cars, trucks, trains, ships and more all use rivets during manufacturing for component attachment. Shake and vibration resistance prevents loosening.
Military/Defense - Rivets create reliable attachments for vehicles, weapons, communications gear, and facilities able to withstand harsh environments during use.
Oil/Gas Industry - Drilling platforms, pipelines, refineries, and mining equipment are constructed with rivets due to their strength and corrosion resistance.
Riveting Process and Equipment
Installing rivets requires several steps to ensure proper strength:
1. Drilling or punching holes for the rivet diameter. Deburring for smooth inner walls.
2. Selecting proper rivet length to match material stack thickness. Correct grip critical for strength.
3. Inserting rivet into holes in materials to be joined. Rivet fully fills hole.
4. Using a rivet gun, hammer, or squeezer to upset the tail, spreading it to form the second head.
5. Inspecting the set rivet for sufficient bulge and head formation to ensure strength.
Pneumatic rivet guns provide portability and power for most applications. Specialized tools like squeezers and counter-sinking tools meet unique needs. Automation like robotic riveting increases production rates.
Testing and Quality Control
For critical applications, rivet joints undergo standardized tests to verify their strength:
- Tensile shear testing pulls riveted samples apart. Measures total strength.
- Fatigue testing vibrates samples through cycles. Confirms fatigue performance.
- Environmental testing exposes riveted materials to salt spray, moisture, and extreme temperatures. Checks corrosion resistance.
Process controls like checking set dimensions and pull testing ensure quality. Statistical sampling verifies consistent production strength.
In summary, rivets play an essential role across countless industries and products. Their versatility, strength, and ease of installation makes riveting a go-to fastening method. While seemingly simple, specialized rivet types, gun tools, and testing ensures reliable performance even under demanding conditions. Understanding proper rivet selection and application is key for engineers and manufacturers seeking robust, cost-effective joints. CNC Milling CNC Machining