High Quality Rivets for CNC Machines - A Guide to Selection and Usage (hardness of material Marcus)
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Rivet Grades - Understanding Strength and Durability
Industrial rivets are available in a range of grades denoting their strength, hardness, and suitability for different uses. Key grades include:
- 1100 Aluminum: Low cost rivets suitable for light duty applications. Not recommended for CNC machining.
- 2011 Aluminum: Moderate strength and good corrosion resistance. Common for general CNC fabrication.
- 2024 Aluminum: High strength aircraft-grade aluminum alloy, but lower shear strength than steel. Used for heavy CNC applications.
- Monel: Excellent corrosion resistance and high strength, but expensive. Used in marine and chemical CNC projects.
- Stainless Steel: Ultimate corrosion resistance and high strength. Ideal for long-lasting CNC fabricated parts.
When selecting rivets, consider not just the grade, but also manufacturing quality - poor quality rivets may not meet their rated specifications. Reputable brands known for consistency, like Huck, Cherry, and Avdel, are recommended.
Rivet Head Styles for CNC Applications
Rivet heads are optimized for different uses, some are better suited for CNC machining. Common head types include:
- Countersunk: Flush smooth head for a clean finish. Used in thin sheet CNC work.
- Universal: Rounded low-profile head. Allows some variation in grip length.
- Large Flange: Higher bearing surface to spread force, but may need countersinking. Good for structural CNC work.
- Structural: Extra wide domed head. Requires pre-drilled oversized holes. Maximum shear/tensile strength.
- Brazier: Distinctive domed head with small center point. Easy to center punch but requires very precise alignment in CNC drilling.
For CNC applications, universal and countersunk heads offer the most flexibility. Structural rivets require very precise positioning but create an incredibly strong bond.
Optimizing Fit with Proper Grip Length
Rivet grip length must be matched to total material thickness for proper fastening without crushing or loosening. Typical aluminum CNC rivets come in 1/16" increments from 1/8" to 1", while structural rivets range from 3/16" to 2".
Use calipers to accurately measure material thickness and select the next increment up for tight fastening. Grip should be snug - a rivet that rattles loosely in the hole risks failure. Having at least 2 full threads protruding past the material ensures optimal grip.
Techniques for CNC Riveting Excellence
With the right rivets selected, proper techniques are vital for a solid finished product:
- Holes must be accurate size - undersized holes risk cracking material when setting the rivet.
- Spotting ensures rivet heads align. Use center punch or center drill to spot holes before CNC drilling.
- Countersink for flush heads. Machine 82° countersinks approximately 1.5x the rivet head diameter to optimize flush finishing.
- Press firmly when setting. Use a pneumatic squeezer on last 10-20% for an ultra-tight set. Avoid excessive squeezing which can crack the rivet stem.
- Set symmetrically. Position rivets consistently on both sides of a workpiece to distribute stress evenly and prevent distortion.
- Deburr thoroughly. Remove any burrs around holes to ensure solid mating between rivet and substrate.
Following these best practices will lead to securely fastened CNC fabricated end-products with clean, uniform finishing. Investing in quality rivets specially designed for machining applications is rewarded with a stronger, higher performance assembly. CNC Milling CNC Machining