Riveting in Sheet Metal Fabrication(bending metal Arthur)
- source:GAENOR CNC Machining
What are Rivets?
A rivet is a short cylindrical rod with a head on one end. The rod is inserted through aligned holes in the materials being joined. The plain end is then deformed with a riveting hammer or tool to create a second head. This process spreads the rivet and locks it in place.
Rivets are made from malleable metals like aluminum, copper, steel, and stainless steel. Aluminum and steel rivets are most common for sheet metal work. The material and alloy can be selected to match or contrast with the metal being fastened.
There are three main types of rivets used in sheet metal fabrication:
- Solid rivets are a single piece of metal. They produce a very rigid connection but can loosen over time due to vibration and shifts in the assembly.
- Blind rivets have a built-in stem that is pulled to deform the rivet. Installation only requires access to one side of the workpieces.
- Split rivets are tubular with a pre-cut slit. The rivet splits and deforms inward as it is set for a tight fit.
In addition to these standard styles, there are a number of specialty rivet types like drive rivets, large-flange rivets, and self-plugging rivets. The geometry and features can be tailored to suit specific applications.
Benefits of Riveting
Riveting in sheet metal fabrication offers numerous benefits:
- Permanent - Once installed, rivets produce an essentially permanent joint that won't come loose over time.
- Strong - The mechanical clinching process deforms the rivet, creating a tight fit that resists shear and tensile loads.
- Quick - Manual, pneumatic, and hydraulic riveting tools allow for fast installation compared to bolts or welding.
- Simple - Minimal equipment is needed for most riveting operations. Hand tools are often sufficient.
- Versatile - Rivets can join dissimilar metals and a range of material thicknesses.
- Reliable - Proven riveting techniques consistently produce sound joints. Quality control is straightforward.
- Appearance - The look of exposed rivet heads is aesthetically appealing on many products.
Riveting is generally a low-cost, user-friendly fastening method. It only requires access to one side of a assembly, unlike bolts or screws. The speed and ease of installation make rivets ideal for high production environments.
Rivet Joint Design
Proper joint design is critical for a sound riveted connection. The materials being joined must be adequately supported so the rivet can clamp and clinch them together. Several design factors should be considered:
- Material thickness - Thicker materials require longer rivets and larger head diameters.
- Hole size - Holes must closely match the rivet diameter for optimal filling and deformation.
- Spacing and pitch - Adequate edge margins and rivet spacing avoids tearing or distortion.
- Load direction - More rivets are needed perpendicular to the applied force.
- Joint type - Lap joints are common but butt, corner, and tee joints are also possible.
- Interference and clearance - Allowance for rivet expansion helps avoid buckling or cracking.
The end goal is maximizing joint strength while preventing fatigue failures around the rivet. Detailed rivet specifications provide the diameters, lengths, spacing, pitches, and design pressures needed.
Riveting Sheet Metal by Hand
One of the simplest methods is riveting sheet metal components together by hand using basic tools. It only requires a riveting hammer, bucking bar, pop rivet gun, and properly aligned materials. Here is an overview of the hand riveting process:
1. Cut components to size and drill matching rivet holes. Deburr edges.
2. Clamp parts together in alignment with C-clamps or vise grips.
3. Select a rivet length allowing 1.5x material thickness protruding.
4. Insert rivet into holes and position bucking bar on back side.
5. Use hammer to upset rivet head on front side while bracing with bar.
6. Flip over and finish forming shop head on backside.
7. Install adjacent rivets using proper spacing and pitch.
8. Check for any cracks or deformation around rivets.
9. File any uneven or sharp rivet heads for safety.
Hand installation takes practice to consistently form symmetrical rivet heads. Production shops normally use pneumatic guns or hydraulic presses for efficiency and quality.
automated sheet metal riveting tools like rivnut and orbital systems allow for very rapid, foolproof installation.
Inspection and Testing
Every riveted assembly should be visually inspected to verify proper clinching. Additional validation may involve:
- Shake or vibrate testing to check for loose rivets.
- Proof loading to confirm rivets meet design shear strength.
- Tensile testing with force applied perpendicular to the joint.
- Peel testing to evaluate rivet clinching and adhesion.
- Microscope examination of rivet clinching and surrounding material.
- Dye penetrant, magnetic particle, or ultrasonic testing to check for hidden flaws.
Destructive testing is sometimes used for critical components and new riveting processes. This provides definitive strength data but ruins the assembly.
Applications of Riveting
Riveting is commonly used to fabricate sheet metal enclosures, ducts, pans, racks, cabinets, shields, and guards. It assembles roofs, walls, floors, and supports in infrastructure. And it joins aircraft and vehicle body panels, wings, doors, and aerodynamic surfaces.
Nearly any sheet metal assembly that doesn't require weld strength can benefit from riveting. The aerospace and aviation industries rely heavily on rivets thanks to their strength, reliability, and lightweight properties. They are alsopopular in manufacturing, construction, food processing, electronics, HVAC, and automotive.
Advancements like self-piercing rivets and flow-drill rivets further expand the applications for sheet metal riveting. Robotic installation platforms provide consistent, rapidsystems for mass production.
The versatility, speed, and dependability of rivets ensure they will remain a trusted fastening method for sheet metal fabrication. Understanding proper joint design, rivet types,and installation methods allows for cost-effective, durable riveted assemblies. CNC Milling CNC Machining