Rivets for Sheet Metal Fabrication(cutting aluminum Levi)
- source:BREDA CNC Machining
What is a Rivet?
A rivet is a mechanical fastener that consists of two parts - a cylindrical shaft and a head. The shaft is inserted into pre-drilled holes in the materials being joined. The tail of the rivet is then upset, or deformed, to create another head that locks the rivet in place. This creates a permanent mechanical connection.
Rivets are available in many materials including aluminum, steel, copper, stainless steel, and more. Aluminum and steel rivets with anti-corrosion coatings are common for sheet metal fabrication. Rivet diameters range from 1/16 inch to over 1 inch. Lengths vary from 1/8 inch for thin materials up to 5 inches for thick materials. The grip range refers to the total thickness the rivet can clamp.
Benefits of Rivets for Sheet Metal
Rivets offer unique benefits for joining sheet metal:
Permanent Fastening: Unlike screws, rivets form a permanent connection that cannot loosen over time. The upset rivet head locks it in place indefinitely.
Strength: Rivet joints are very strong in shear and tension and rivals welding for many applications. Proper rivet selection prevents joint failure.
Vibration Resistance: Riveted joints can withstand high vibration better than many other mechanical fasteners. Rivets are commonly used in aircraft and vehicles.
Corrosion Resistance: Many rivets have anti-corrosion coatings that prevent oxidation and galvanic corrosion. Stainless steel rivets provide corrosion resistance even without coatings.
Quick Installation: Riveting is very fast compared to welding or adhesives. It takes just seconds to upset a rivet. Automated tools further increase speed.
Lower Skill Requirement: Riveting only requires basic training compared to the high skill needed for welding. No hazards or certification needed.
Appearance: The smooth appearance of flush rivets provides an appealing industrial look. Colored rivet heads can also be used for aesthetics.
Rivet Joint Design Considerations
Properly designing riveted joints requires considering several factors:
- Rivet diameter - must match material thickness and desired strength. Larger is stronger.
- Rivet length – should match total material thickness but not be excessively long.
- Rivet material – aluminum and steel are most common. Must match/exceed strength of materials.
- Rivet head style – countersunk, round head, brazier head. Impacts appearance and clearance.
- Rivet pattern – staggered rows provide better load distribution than single rows. Edge margins prevent tearing.
- Hole size – clearance between rivet and hole impacts alignment and strength. Interference fits are stronger but difficult to install.
- Material factors – strength, hardness, thickness, corrosion resistance all impact joint design.
Proper joint design is crucial for rivets to perform as expected. Engineers should calculate joint strength based on rivet properties and loads.
Rivet Installation Equipment
Installing rivets requires tooling to drill holes, insert rivets, and upset the tails. Here are the most common riveting tools:
- Drill press – For intermittent hole drilling. Fixturing ensures hole alignment.
- CNC drill/router – For mass production hole drilling. Precisely locates holes.
- Pneumatic rivet gun – Uses air pressure to insert and upset rivets. For portable on-site installation.
- Impulse rivet gun – Uses electromagnetic impulse to upset rivets. Handheld tool for precision assembly.
- Automatic riveting machine – Feeds and installs rivets automatically. For mass production.
- Robotic riveting system – Robots with rivet tools for automated precision riveting. High volume applications.
- Manual rivet sets and hammers – For occasional small jobs andsheet metal hobbyists. Requires skill.
CNC routers are ideal for quickly drilling large numbers of precision holes in panels for mass production. Robotic riveting systems allow complete automation for very high volumes.
Rivet Installation Process
Here is the basic process for riveting sheet metal components together:
1. Design joint geometry and rivet pattern based on load requirements.
2. Select rivet type and size based on materials and design loads.
3. Program/set up CNC machine for hole drilling positions. Clamp layers together.
4. Drill holes using sharp high-speed drill bits. Deburr holes.
5. Insert rivets into holes. Locate head against one side of material.
6. Use rivet gun to upset tail and form second head locking rivet in place.
7. Inspect rivets for proper head formation and clamping.
8. Repeat riveting process across entire joint surface to complete connection.
9. Clean assembled part to remove drilling chips, oil, and debris.
For critical applications, quality checks should verify rivet length, hole size, grip, and rivet head formation meet standards.
Rivets offer fast, simple, and economical permanent joining of sheet metal components. When properly designed and installed, riveted joints provide excellent strength and durability even under demanding loads and environments. Drilling CNC machines combined with modern pneumatic, impulse, or robotic riveting systems allow very high productivity and quality rivet installation for both small job shops and large mass production facilities. Riveting will continue growing as a preferred method of sheet metal fabrication across many industries. CNC Milling CNC Machining