Riveting in Sheet Metal Fabrication(is brass stronger than bronze Sid)
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Understanding Rivets
Rivets are usually made from steel, aluminum, copper, or stainless steel. The shaft of the rivet slides into a pre-drilled hole in the materials being joined. The rivet is then deformed with a riveting hammer, die, or rivet gun, causing the rivet to expand and clamp the layers together. The rivet shank deforms, usually upsetting or buckling, while the rivet head supports the material layers.
Rivets come in many sizes and styles for different applications:
- Solid rivets are a single piece and the most common type.
- Blind rivets, also known as pop rivets, can be installed on one side when there is only access to one surface.
- Drive rivets have a pre-formed head and are driven into a die cavity on the opposite side.
- Split rivets have a pre-cut split down the shank so they can expand easily.
- Tubular rivets are hollow and deform like a crimped tube when set.
Advantages of Riveting
Riveting offers benefits over other mechanical fastening methods like welding, screws, and bolts:
- Permanent joint - Rivets form a permanent clamping force between materials. Vibration cannot loosen rivets over time.
- Strength - Properly installed and designed rivets provide excellent shear and tensile strength. The rivet clampload determines joint strength.
- Material versatility - Rivets can join dissimilar metals. Common combinations include steel-aluminum and copper-steel.
- Quick installation - Rivet guns allow fast installation times, ideal for mass production and assembly lines.
- Low skill - Minimal training is required for operators to learn how to efficiently rivet components together.
- No finish damage - The riveting process does not melt or discolor surrounding metal like welding. It's ideal when preservation of the original surface finish is needed.
Riveting in Sheet Metal Applications
Riveting is commonly used to join sheets of metal when a sturdy, permanent joint is required. Typical sheet metal fabrication applications that rely on riveting include:
Aircraft Construction
Aircraft bodies and wings involve joining thin aluminum skin sheets to internal frames and stringers. Hundreds of thousands of solid aluminum rivets may be used on a single aircraft for fatigue resistance.
Automotive Components
Riveting assembles auto body panels like doors, hoods, and trunk lids. Self-piercing rivets allow direct joining of dissimilar metals on cars without pre-drilling.
Appliances
The outer case of appliances like refrigerators and washing machines use steel rivets to clinch sides and panels together in a tight seam. Tubular rivets add leak resistance.
Electronics
Small delicate electronics like cell phones and laptops are assembled with tiny aluminum blind rivets that get set by automated riveting machines.
Construction and Roofing
Steel rivets fasten building frames, cranes, bridges, and roofing panels where welded connections are unsuitable. Large structural rivets over 1" diameter can join girders and beams.
CNC Riveting
Computer numerical control (CNC) machines can automate the riveting process for high-volume manufacturing. Typical CNC riveting methods include:
- Automatic drilling and riveting eliminates handling steps between operations.
- Robotic arms maneuver rivet guns into accurate positions for fast precision riveting.
- Auto feeders supply rivet guns with fresh rivets as needed for continuous joining.
- Smart cameras and sensors check rivet placement quality and detect defects.
- Computer control allows flexible riveting patterns and custom joint designs.
CNC-automated riveting provides consistency in quality and rivet pitch compared to manual methods. Rivet guns can insert over 60 rivets per minute in ideal conditions. Flexible tooling changes allow fast transitions between rivet sizes and materials during production.
While automation increases throughput, manual riveting still has advantages in small batch and prototype fabrication. Variables like material stackups and accessibility often require operator skill and judgement when riveting custom components. Both methods remain important ways to join sheet metal.
Conclusion
Riveting endures as a quick, strong, and reliable sheet metal joining method after over 5000 years of use. Advances in rivet quality and installation processes open new performance capabilities and fabrication options. Whether in aircraft building, precision instruments, or basic repairs, the versatility of rivets will ensure their use continues long into the future. CNC Milling CNC Machining