Ensuring High Quality Rivets for CNC Applications(cnc fixtures Reginald)
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- source:GAENOR CNC Machining
What are Rivets?
A rivet is a mechanical fastener that connects two or more materials by inserting a metal rod through aligned holes in the materials and deforming the free end of the rod. The deformation creates a head on the rivet, securing it in place. Rivets come in a variety of head shapes, materials, diameters and lengths to accommodate different applications.
Benefits of Rivets
Rivets offer numerous advantages that make them a popular choice for CNC and other manufacturing uses:
- Strong, reliable connections - The mushrooming effect when rivets are installed creates a tight, permanent joint. This prevents loosening over time from vibration or load stress.
- Quick installation - Rivets can be installed rapidly with the right tools, ideal for automation with CNC machines. No nuts/bolts to tighten.
- Variety - With diverse options in materials, sizes and head shapes, rivets can accommodate many joint design needs.
- Weight savings - Rivets are lighter than many welding or bolting methods. This helps reduce finished product weight.
- No special skills needed - Basic training is all that’s required for rivet installation and inspection.
Why Rivet Quality Matters for CNC
For automated CNC operations, inconsistent or poor quality rivets can lead to numerous headaches:
- Production delays - If rivets jam or break in feed systems, the CNC process halts until cleared.
- Weak joints - Rivets that deform improperly may not form a tight connection, compromising product integrity.
- Re-work and rejects - Bad rivets mean scrapped product and extra time spent on repairs.
- Equipment damage - Excessively hard or brittle rivets that shatter could lodge debris in CNC drill bits or other tooling.
Clearly, subpar rivets equal lower productivity and profits. By sourcing rivets meeting key standards, manufacturers can avoid these issues.
Standards for Quality Rivets
Several criteria help determine if a rivet will perform reliably in CNC applications:
- Materials - Aircraft quality rivets use hardened aluminum alloys or steel for strength. Avoid pure aluminum.
- Ductility - The rivet must deform and mushroom properly without cracking. Ductile materials like 1100 aluminum are ideal.
- Head shape - Countersunk, round head, flat head and other head types suit different uses. Verify head dimensions.
-Dimensional uniformity - Precise, consistent sizing of diameters and lengths prevent jamming in CNC feeds.
- Surface defects - Cracks or voids compromise strength. Rivets should have smooth, flawless finishes.
- Hardness - Rivets should be sufficiently hard to resist loosening but not brittle. 50-90 on Rockwell B scale is typical.
- Testing data - Reliable manufacturers supply proof of quality testing for shear strength, hardness, ductility, etc.
Reputable rivet suppliers design their products specifically to meet the demands of CNC environments. Always check that potential suppliers follow applicable standards and can furnish supporting test data.
Inspecting Rivets
To confirm an incoming batch of rivets meets specifications, several inspections are recommended:
- Dimensional - Use calipers, micrometers and other instruments to check diameters, lengths, head shapes and other dimensions against the product datasheet.
- Visual - Examine a sample under a magnifier to check for surface defects like cracks or porosity. A dye penetrant test can further reveal flaws.
- Hardness - Specialized machines can efficiently test rivet hardness. Portable hardness testers can also provide sample testing.
- Shear/tensile strength - Destructive testing methods like shear or tensile load testing determine the rivet’s strength.
- Chemical composition - For aircraft rivets, chemical analysis ensures the alloys match required material specs.
By performing even a basic visual inspection, manufacturers can avoid integrating defective rivets into production. For more rigorous testing, accredited labs can be utilized to periodically validate rivets.
Proper Rivet Storage
Rivets that pass incoming inspection must then be stored correctly to maintain quality:
- Cool, dry area - Moisture causes corrosion in metal rivets. Avoid temperature extremes which could alter temper.
- Sealed packaging - Contents should be protected from dust, debris and other contaminants.
- Organized storage - First-in-first-out (FIFO) stock rotation helps avoid aging. Older stock should be periodically re-tested.
- No commingling - Keep different rivet types, sizes, alloys, etc in separate marked bins to prevent mix-ups.
By actively managing rivet inventory, manufacturers prevent degrading of the fasteners before use.
Achieving CNC Success with Quality Rivets
From component design to final assembly, choosing the optimal rivets enhances CNC performance and productivity. Verifying rivet quality at incoming inspection, properly storing and handling inventory, and partnering with reputable suppliers leads to precision end-products free of fastener failures. With sound riveting practices, manufacturers can feel confident in their automated processes and finished output. CNC Milling CNC Machining