Riveting in Sheet Metal Fabrication(strip plating Quincy)
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- source:GAENOR CNC Machining
What is a Rivet?
A rivet is a mechanical fastener that connects two or more sheets of material by passing a shaft through holes in the sheets and forming a head on each end. Rivets are typically made of steel, aluminum, or titanium.
The rivet shaft fills the hole in the materials being joined and the heads on either end mechanically clamp them together. The force created by the deformed heads pulls the materials tightly together creating a strong joint.
Types of Rivets for Sheet Metal
There are two main types of rivets used for sheet metal fabrication:
- Solid/ blind rivets - These have a preformed head on one end and are driven using a riveting tool to form the second head. They can join materials where access is only available from one side.
- Tubular rivets - These have a hollow shaft and are driven using a bucking bar on the backside to flare out the tail forming the second head. Access to both sides of the materials is required when using tubular rivets.
Common rivet materials are steel, aluminum alloy, copper, and titanium. Steel and aluminum alloy rivets are the most popular for sheet metal work.
Benefits of Riveting Sheet Metal
Riveting offers several benefits for joining sheet metal:
- Permanent - Once installed, the rivets remain in place indefinitely, helping the joint resist vibration and shock loads.
- Strength - The large contact area of the rivet heads creates a very strong joint. Rivets are preferred for highly stressed connections.
- Simplicity - Riveting requires simple tools and the process can be easily automated. Minimal training is required for operators.
- Flexibility - Multiple sheets can be joined together in a variety of configurations. Stacked, lap, and butt joints are all possible.
- No Heat or Curing - Mechanical fastening eliminates heat from welding or waiting for adhesives to cure. Often riveting is the fastest joining method.
- Appearance - The smooth exterior surface of tubular rivets provides a clean finished look, preferred for visible applications.
Riveted Joint Design
Properly designing riveted joints is critical to achieving maximum strength and durability. Here are key factors to consider:
- Material Thickness - Thicker materials require larger diameter rivets to develop sufficient clamping force. The rivet diameter should be approximately 2.5 times the combined thickness of sheets.
- Hole Size - Holes must be large enough for rivet insertion but small enough for tight engagement. For most applications, hole diameter is 1.1 times the rivet diameter.
- Spacing and Pitch - Rivets should be spaced 3-4 diameters apart longitudinally and 2-3 diameters apart laterally. Closer spacing reduces joint efficiency.
- Rows - Multiple parallel rows may be required for long joints or heavy loads. Staggering rows increases strength.
- Edge Distance - Rivets should be placed at least 1.5 diameters from sheet edges. Increasing edge distance boosts joint strength.
- Washer Plates - Backup washers can be riveted in place to reinforce thin materials and prevent pull-through damage.
Riveting Process
Installing rivets to create high quality joints involves following a systematic process:
1. Sheet Preparation - Cut materials to size and drill properly sized holes at marked locations. Deburr holes.
2. Assembly - Clamp and hold sheets in alignment. Insert rivets into holes.
3. Riveting - Use appropriate tools to upset both heads and securely clamp materials. Avoid damage during flaring.
4. Inspection - Check all rivets for proper head formation, clamping, and positioning. Reinstall any loose or defective rivets.
5. Finishing - Sand protruding rivet edges smooth if needed. Apply sealants or protective coatings over joints when specified.
Riveting Tools
A variety of manual, pneumatic, and hydraulic tools are available for riveting sheet metal. Choosing the right tools improves efficiency and joint quality.
- Squeeze Riveters - Hand operated plier style tools for solid rivets. Best for small scale, intermittent riveting.
- Pneumatic Rivet Guns - Air powered tools provide powerful, consistent pulling force for both solid and tubular rivets. Most common for production environments.
- Battery Riveters - Portable and eliminate need for compressor. Limited pulling force makes them better suited for solid rivets.
- Hydraulic Riveting - Hydraulic power source allows tremendous pulling forces for large tubular rivets. Used in heavy fabrication.
- Autofeed Tools - For high volume production, autofeed tools deliver rivets automatically for rapid installation. Often used in automated lines.
Riveting provides a fast, simple way to create strong permanent joints in sheet metal assemblies. By following proper design principles and process techniques, high quality and consistent results can be achieved. The wide range of available riveting tools makes the process highly adaptable for both low and high volume fabrication needs. CNC Milling CNC Machining