Riveting in Sheet Metal Using CNC Machines(what is delrin Stanley)

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Riveting is a crucial process in sheet metal fabrication that joins two or more metal sheets together using rivets. With the advancement of technology, computer numerical control (CNC) machines are now commonly used to automate and streamline the riveting process for high productivity and precision.
Introduction to Riveting
Riveting involves inserting a metal fastener called a rivet through holes in the parts to be joined and deforming the protruding ends using a riveting hammer, squeezer or other riveting tools. The deformed ends are called buck-tailed heads and they mechanically fasten the sheets together.
Rivets come in different head shapes, materials and specifications to suit various applications. Some common types are solid rivets, semi-tubular rivets, blind rivets and drive rivets. The choice depends on factors like joint strength, accessibility, and assembly method.
Benefits of Riveting in Sheet Metal
Compared to other joining techniques like welding and adhesive bonding, riveting offers several benefits:
- It is a purely mechanical process so no heat or chemicals are involved. This prevents thermal distortion or corrosion problems.
- Riveting creates highly reliable and vibration-resistant joints.
- The process is flexible and relatively low cost. Many rivet sizes and materials are available.
- Riveted joints can be disassembled if required for maintenance or part replacement.
- Minimal surface preparation is needed compared to welding or adhesive bonding.
- Riveting has a long history of use and is a well-established fabrication technique.
Automated Riveting with CNC Machines
Performing riveting manually is labor-intensive, slow and inconsistent. CNC automation improves the process considerably through:
Precise Hole Positioning
- CNC machines drill holes for the rivets with extreme accuracy using programmed hole patterns. This ensures rivets line up properly.
- Hole size and spacing are optimized to suit the rivet dimensions and joint design.
- Multiple sheet layers can be drilled in one shot for perfect alignment.
Automated Rivet Insertion
- CNC-controlled pneumatic, servo or hammer riveting heads precisely insert each rivet into the prepunched holes.
- Correct force is applied to properly seat the rivet without damage.
- Different rivet types and sizes can be handled as per the program sequence.
- Rapid insertion improves productivity compared to manual fitting.
Consistent Rivet Forming
- The rivet upset process is automated for uniform bucktail formation within tight tolerances.
- Servo riveters allow precise closed-loop control of rivet forming force and displacement.
- Multi-hit riveting heads are used for challenging joints that need sequential forming hits.
- Automated rivet forming ensures reliable, repeatable joints.
Advanced In-Process Monitoring
- Vision systems, force sensors and other sensors provide real-time monitoring during the automated riveting process.
- Out-of-tolerance conditions like hole misalignments, missing or damaged rivets can be immediately flagged.
- The monitoring data helps optimize the riveting programs and tools over time.
Reduced Labor, Faster Production
- CNC riveting minimizes the need for skilled manual labor. Operators only have to load sheets into the machine.
- Automation enables much faster riveting compared to manual methods.
- Multi-spindle CNC riveters can insert hundreds of rivets per minute in complex patterns.
- Faster production, lower costs and shorter delivery times are achieved.
Riveting Large Sheet Assemblies
CNC riveting is ideal for fabricating large sheet metal components like aircraft fuselages, truck/bus bodies, rail car shells, etc. that use thousands of rivets. Hand riveting such large assemblies would be impossible.
Other automated processes like laser welding face problems with accessibility inside huge assemblies. But CNC riveting can easily insert and upset rivets in internal joints using specialized riveting heads that can navigate the internal structure.
Flexibility of CNC
A major advantage of CNC machines is their programmability to handle a wide range of riveting applications by simply changing the control program. Here are some possibilities:
- Varying rivet locations, patterns and sequences
- Using multiple rivet sizes and types
- Changing number of rivets and joint configurations
- Modifying drilling, insertion and upsetting parameters
- Adapting to different sheet metal materials and thicknesses
- Inserting other fasteners like lockbolts if required
- Adding robotic material handling for automation of the full process
By storing programs for different products, CNC enables flexible high mix, low volume production. Riveting patterns can also be optimized for strength requirements using advanced simulation tools.
Quality Control of CNC Riveting
CNC riveting provides excellent process control, but additional quality checks are still necessary:
- Dimensional inspection of hole positions and rivet patterns
- Pull testing of riveted samples to validate joint strength
- Disassembling random joints for rivet length and grip inspection
- Monitoring for cracks or deformation during rivet upset
- Periodic in-process checks by operators as a redundancy
The collected quality data helps fine-tune the CNC programs and tools. Automated inspection systems like coordinate measuring machines can also be integrated to provide rapid feedback for process improvement.
Safety is also critical considering the high forces involved. Proper guarding, safety interlocks and personal protective equipment must be used.
Future of Automated Riveting
CNC riveting technology continues to advance with greater automation, precision, flexibility and intelligence through:
- More powerful servo riveting heads with advanced force control
- Increasing use of robots for material handling and riveting access
- Self-piercing rivets that don't need prepunching
- Vision and sensor systems for automated in-process inspection
- Improved simulation of riveting dynamics and joint strength
- Integration of riveting data with manufacturing analytics software
- AI-based analysis for predictive maintenance and process optimization
- Human-machine collaboration with operators working alongside robots
The automated and data-driven nature of smart CNC riveting systems will enable further improvements in riveted joint quality, productivity and cost-effectiveness. This will solidify riveting as a key fabrication technique well into the future, especially as industries strive for higher levels of manufacturing automation. CNC Milling