Uses for Rivets in CNC Machining(anodized aluminum Aries)
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What Are Rivets?
A rivet is a mechanical fastener that joins two or more materials by deforming its shank. The rivet shank fills a hole drilled through the parts to be joined and a head is formed on one or both ends, clamping the materials together. Rivets are available in a variety of materials and head styles to suit different applications. Common materials include steel, aluminum, copper, and titanium.
Advantages of Rivets vs. Other Fasteners
Compared to other mechanical fasteners like screws or bolts, rivets offer several advantages:
- Permanent - Once installed, rivets cannot come loose or unscrew like threaded fasteners. This makes them ideal for critical structural joints.
- Vibration resistant - Riveted joints can withstand high vibration environments better than threaded fasteners.
- Flush heads - Many rivet styles have flat heads that provide a smooth surface and avoid protrusions. This improves aesthetics and reduces snagging.
- Quick installation - Rivets can be quickly installed with hand tools or pneumatic riveters without needing to cut threads or torque specifications.
- Material flexibility - Rivets can join dissimilar materials like metals to composites. Not all fasteners are suitable for these combinations.
- Lightweight - Aluminum and titanium rivets are common in aerospace applications where minimizing weight is critical.
These inherent advantages make rivets a staple in CNC machined parts and assemblies across industries.
CNC Machining Considerations for Rivets
To utilize rivets effectively in CNC machined components, engineers should consider several factors:
Hole Diameter Tolerances: The holes for rivets must be precision machined for proper fit. Recommended diameter tolerances are ±0.1 mm (0.004 in) or less. Tighter tolerances result in consistent rivet deformation.
Hole Position Alignment: Misalignment of rivet holes will cause eccentric loading on the rivet and joint. CNC hole positions should be controlled to within ±0.1 mm (0.004 in) true position accuracy.
Clamping Force: Each rivet size and material has a recommended clamping force. Proper tooling and pressure settings must be used to achieve target deformation force. Excess force can damage the rivet or workpieces.
Rivet Spacing: Follow recommended edge distances and rivet pitch when laying out hole patterns to distribute load appropriately. Typical spacing is 2-4 times the rivet diameter.
Interference Fits: Some applications utilize interference fit rivets that create a pressed fit by being slightly oversized relative to the drilled hole. This provides tighter structural joints but requires extra force to install.
Flush Head Clearance: Flush rivets require flat mating surfaces to form a flush head. Add a chamfer if the backside is inaccessible to avoid damaging the protruding rivet.
Tooling Selection: Pneumatic, hydraulic, impact, or squeeze riveters must be matched to the rivet size and materials used. Proper tooling improves quality and reduces fatigue.
Inspecting Joints: Visually confirm proper rivet deformation and check for cracks or inadequate compression after installation. Non-destructive testing can also verify joint integrity.
By considering these factors and following manufacturer recommended guidelines, CNC machined parts can take full advantage of rivets as an assembly method.
CNC Applications for Rivets
Rivets have many useful applications in CNC machining across industries, including:
Aerospace: Rivets are extensively used to join aircraft fuselage skins, bulkheads, wings, and other structural components where vibration resistance and light weight are critical.
Automotive: Rivets provide durable structure in automotive chassis components, brackets, driveline parts, and panels. Resistance to vibration and corrosion makes them ideal for vehicles.
Appliances: The outer shells of appliances often use rivets for aesthetic joining of panels and housings without threaded fasteners. Stainless steel rivets withstand corrosion and cleaning chemicals.
Electronics: Small aluminum or plastic rivets assemble casing and internal components of electronics that require access for service or airflow. Rivets avoid threads that can wear out.
Construction: Steel rivets join prefabricated structural beams and gussets for bridges, cranes, and buildings. Riveting provides permanent structural joints.
Signage: Rivets mount plastic and metal signage to poles and building exteriors. Their permanence prevents loosening and theft better than screws.
Furniture: Riveting is an alternative to welding for assembling aluminum outdoor furniture. Rivets allow knock-down assembly and hide fasteners for clean aesthetics.
With CNC machining’s precision accuracy and repeatability, rivets can be incorporated into designs knowing each hole and joint will be uniformly produced. This enables manufacturers to leverage the benefits of rivets across nearly any application needing robust and reliable mechanical joints.
Conclusion
Rivets have been used since antiquity to permanently join materials, making them one of the oldest and most proven mechanical fastening methods. Their vibration resistance, material flexibility, lightweight potential, and quick installation continue to make rivets a highly useful option for CNC machined components and assemblies. By applying best practices around hole precision, joint design, tool selection, and quality control, manufacturers can implement rivets as a fastening solution that withstands the test of time. Rivets are a CNC-compatible fastening technology poised to maintain relevance long into the future. CNC Milling