Riveting in Sheet Metal Fabrication with CNC(torsion snap joints Caroline)

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Rivets have been used since ancient times to join pieces of metal together. While welding has become more common, riveting is still an important technique, especially in sheet metal fabrication. Using computer numerical control (CNC) machines has made riveting much more efficient and precise.
How Riveting Works
A rivet is a mechanical fastener that joins two or more sheets of material by expanding its shank. A rivet gun is used to drive the rivet by pulling its cap, causing the shank to flare out and grip the materials. The flared end is called the shop head, while the flattened original end is the bucktail.
Rivets come in many sizes and materials. Some common types are:
- Solid rivets - Made of a single material like steel, aluminum, copper. Most versatile rivet type.
- Semi-tubular rivets - Hollow and lightweight while still strong. Often used in aircraft.
- Blind rivets - Can be installed from one side when there is only access to one part surface.
- Drive rivets - Designed to replace solid shank rivets. Easier to install.
- Structural rivets - Used for critical structural applications. High shear and tensile strength.
Benefits of Riveting
Compared to other fastening methods, riveting offers:
- Strength - The flare created firmly joins materials without loosening. Critical for aircraft.
- Durability - Does not corrode or degrade like adhesives or welding.
- Reusability - Rivets can be removed and replaced if needed for repairs or alterations.
- Appearance - Provides a smooth finished look compared to screw or bolt heads.
- Cost - Relatively inexpensive fastening method per unit.
- Versatility - Many rivet types and alloys available to suit different material and strength needs.
CNC Riveting Machines
Performing riveting manually is labor intensive and inconsistent. Using CNC machines automates the process for improved speed, precision, and quality. There are several types of CNC riveting machines:
- CNC rivet gun - Uses servo motors to manipulate a standard pneumatic rivet gun through programming. Allows riveting in any orientation.
- CNC riveting head - Motorized head precisely positions and sets rivets in one stationary location. Used for high volume production.
- CNC riveting station - Combines a riveting head mounted on a movable gantry for flexible riveting of large parts.
- Robotic CNC riveting - Industrial robots outfitted with riveting end effectors for maximum flexibility and range of motion.
CNC Programming for Riveting
CNC allows riveting patterns and locations to be precisely programmed ahead of time. This requires 3D models of the parts and advanced programming skills.
The basic process includes:
1. Import 3D CAD models of the parts into CAM software.
2. Select rivet type and assign riveting points onto the 3D model surfaces.
3. Program positioning moves for the rivet gun/head to reach each rivet point.
4. Set order of operations, spacing, hole alignments if necessary.
5. Program pressure settings and riveting depth for quality fastening.
6. Simulate program to verify feasibility and catch errors.
7. Generate G-code program to load into the CNC machine.
8. Perform test runs on scrap material to check fit and quality.
9. Run production riveting cycle.
10. Inspect finished parts for any missed or improperly set rivets.
Benefits of CNC Riveting
Transitioning from manual to CNC riveting provides many advantages:
- Consistent quality - Rivets are positioned precisely and set with ideal force.
- Increased speed - CNC applies rivets much faster than manual fabrication.
- Reduced waste - Automation avoids human error and rework.
- Flexible production - Easily switch rivet patterns with different CAD models.
- Safety - Removes worker exposure to repetitive motion injuries.
- Scalability - CNC allows limitless riveting capacity scaled to demand.
- Cost savings - Faster cycle times mean lower operating costs.
Riveting remains an important metal fastening solution even as technology advances. CNC automation makes the process more efficient and error-proof while expanding possibilities for rivet design. With the right programming, CNC riveting can improve quality and output for all types of sheet metal fabrication. CNC Milling CNC Machining