Uses for Rivets in CNC Machining(facing tool lathe Martina)

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Rivets are a fundamental fastening system used across many industries, especially in metal fabrication and manufacturing. While welding has become the dominant assembly method in recent decades, riveting still plays an essential role for certain applications and materials. For shops using computer numerical control (CNC) machining, understanding where and how to utilize rivets can lead to faster, lower cost, and more durable products.
What is a Rivet?
A rivet is a mechanical fastener consisting of two main parts - a smooth cylindrical shaft and a head. The rivet is inserted into pre-drilled holes through the materials being joined, and the tail end is mechanically deformed, typically using a rivet gun. This flares out the tail and clamps the rivet in place. The flared end acts like a second head, creating a strong joint.
Advantages of Rivets vs. Welding
Riveting offers several benefits that make it preferable to welding for certain CNC applications:
- Works on dissimilar materials: Rivets can join different metals or other materials that may be difficult to weld together. The mechanical connection avoids metallurgical issues.
- Minimal distortion/warpage: Welding creates localized heat that can distort or warp thin materials. Riveted connections have less impact on the original material geometry.
- Quick and portable: Riveting is far faster than welding for assembling large components. It also does not require bulky equipment, making riveting ideal for field repairs and installations.
- Shear and vibration resistance: The multi-point connections created with rows of rivets are excellent at resisting shear stresses and vibration forces. Welds are prone to fatigue failure under such loads.
- No consumables: The rivets themselves are the only consumable, unlike the filler rods/electrodes required for welding. Less cost for supplies.
- Appearance: The smooth finish of rivet heads can be preferable aesthetically for visible surfaces where weld beads would detract.
Common Uses for Rivets in CNC
Rivets continue to be specified for joining sheet metal, plastic and fiber-based components produced on CNC machining centers. Here are some of the most common applications:
Aircraft Assembly
Riveting remains the standard for aircraft assembly. The many aluminum and composite skin panels that form the exterior, wings, fuselage and other structures are riveted together over internal supports. Rivets also join stringers, ribs and bulkheads. Aircraft-grade rivets are exceptionally reliable and predictable fasteners.
Enclosures & Frames
Electronic enclosures, equipment housings, trailer/RV frames, and storage containers commonly utilize rivets for assembly. The modular nature of riveted construction allows enclosures and frames to be shipped unassembled at lower cost. Riveting also simplifies field maintenance or modifications.
For heating, ventilation and air conditioning (HVAC) ductwork made from sheet metal, rivets provide strong and airtight joints at seams and connections. Welding would introduce heat distortion and requires accessibility for welding torches, while rivets can be installed from one side.
Automotive Components
While high-volume vehicle assembly relies primarily on spot welding, rivets are still used for attaching certain automotive components. Examples include seat frames, inner fender panels, brackets and trim pieces. Rivets are preferred over welding to avoid heat distortion on smaller plastic and metal parts.
Appliances like dishwashers, refrigerators and ovens use rivets to assemble the outer wrapper or skin over the insulation and inner structural chassis. The manufacturing process typically stamps the enclosure panels, then folds and rivets them around the framework.
CNC Riveting Processes
CNC machining centers can be equipped with riveting capabilities for automated and accurate placement. Here are some of the most common CNC riveting methods:
Pin Riveting
A punch and die set in the machine clamps and deforms a semi-tubular rivet pin. The protruding pin shank expands within a pre-drilled hole to flare against the opposite side surface. Best for softer aluminum and plastic materials.
Blind Riveting
Blind rivets allow connection of materials from only one side, where access is limited. The rivet insert pulls a collar tight against the surface as the setting tool pulls on the mandrel shaft. Common for sheet metal enclosure panels.
Self-Piercing Riveting
As the name implies, this style has a pointed rivet that pierces through stacked material layers without pre-drilled holes. The specially shaped tip punches a hole and spreads outward to lock in place. Eliminates hole alignment issues.
Orbital Riveting
A spherical-headed fastener is driven into a spiral motion to flare out and fill the receiving hole. Minimal clamping pressure required. Common for softer materials like plastics that could crack under excessive pin riveting force.
Selecting the Best Rivets
With so many rivet types and materials available, it is important to select the optimal option for your CNC application:
- Material - aluminum, steel, copper, plastic or specialty alloys
- Head style - domed, countersunk, large flange, etc.
- Drive system - smooth (presses in), serrated (cuts in), break stem, break mandrel
- Strength - shear and tensile ratings
- Grip range - length to fit material stack-up
- Environmental resistance - corrosion protection, temperature rating
Consulting with your fastener supplier is always advisable early in the design process to match the rivet to your specific joint requirements, materials and quality standards.
While welding remains the fastest way to join metal structures, riveting is still relied upon for an array of manufacturing applications. CNC machining provides the precision and automation to make riveted assembly more economical versus manual installation. With the right rivet specifications matched to the design needs, rivets can create durable and attractive fabricated products at lower cost than welding in many situations. CNC Milling