Riveting in Sheet Metal Fabrication(types of spring Walker)
- source:MAJA CNC Machining
What is a Rivet?
A rivet is a mechanical fastener that consists of two main parts - a smooth cylindrical shaft and a head. The shaft is inserted through holes in the materials being joined. The excess length of the shaft extends out the backside and is mechanically deformed to create a second head. This process is called riveting or “bucking” the rivet. The force of the setting tool spreads the shaft, locking the rivet in place.
Rivets are commonly made from aluminum, steel, copper, or Monel (a nickel-copper alloy). The hardness and shear strength required depends on the application. Aircraft grade aluminum rivets are lightweight but have excellent tensile strength. Steel rivets can withstand higher shear loads. Monel is very resistant to corrosion and high temperatures.
The head styles can be round, flat, or countersunk to sit flush with the material surface. Rivet heads also contain grooves, divots, or rings that help improve retention strength.
Benefits of Riveting
Compared to welding, soldering, or adhesives, riveting offers many advantages:
- Permanent Joints – Once riveted together, the materials stay securely fastened for the life of the product. Vibration and shock loads do not loosen riveted connections.
- No Heat or Chemistry – The cold mechanical process does not melt or alter the joined materials. Riveting is suitable for heat-sensitive metals and precise alloys. It does not require chemical solvents that can outgas or weaken over time.
- Strength – The compressive forces of the rivet deformation create very strong joints. Rivets withstand shearing and tensile stresses better than many other mechanical fasteners.
- Inspection – Installed rivets are easily inspected visually or with simple go/no-go gauges to check for proper setting.
- Adjustability – Drilled rivet holes allow more latitude in fitting parts together compared to welded joints. Shims can be inserted to adjust alignment if needed.
- Disassembly – Rivets can be drilled out if items need to be taken apart for repair or alterations. The process does not damage the base materials.
Riveting Sheet Metal Parts
Riveting is commonly used to join sheet metal components in aircraft fuselages, automobile chassis, building facades, electronic enclosures, ductwork, and various machines. The process involves several steps:
1. Cutting/Forming Metal Pieces – Sheets are cut to size and bent into required shapes using presses, brakes, or CNC machines. This creates the individual parts to be joined.
2. Drilling Holes – Matching holes are drilled along the seams or overlap areas using drill presses, CNC drilling machines, or robotic arms.
3. Hole Preparation – The holes are deburred to ensure clean edges. Countersinks are added to recess rivet heads flush with the surface.
4. Fitting Parts Together – Parts are assembled and aligned using clamps or assembly jigs. Adjustments are made as needed.
5. Inserting Rivets – Rivets are inserted into the aligned holes. The shaft extends out the backside of the materials.
6. Bucking the Rivet – A bucking bar holds the materials together from the backside. The rivet gun on the frontside heads the rivet using squeezing or impact force. This upsets the shaft, securing the rivet.
7. Inspection – The set rivets are examined to verify proper installation and strength. Failed rivets are drilled out and replaced.
8. Finishing – The edges are sanded, ground, or deburred to remove any burrs or ridges from the riveting process. Protective coatings can then be applied.
For large-scale manufacturing, the riveting process is automated using CNC machines and robots that drill holes, insert rivets, and set the heads precisely and consistently. Automated inspection systems also check for flaws in the finished rivet joints.
The extensive use of riveting to assemble sheet metal parts is a testament to the reliability, versatility, and effectiveness of this simple but powerful fastening technology. As manufacturing continues to advance, innovations in riveting improve speed and integration while ensuring strong joints in sheet metal fabrications across industries. CNC Milling CNC Machining