High Quality Rivets for Precision CNC Machining(snap joint Olive)
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- source:BAGANZ CNC Machining
When riveting with computer numerical control (CNC) machines, not just any standard rivet will do. CNC riveting requires rivets with very tight diameter tolerances that are specially designed for automated installation. Using subpar quality rivets can lead to jamming in automated feed systems, irregular and weakjoints, and rejected parts. Investing in top-of-the-line rivets designed specifically for CNC processes saves manufacturers time, money, and headaches down the road.
In this article, we’ll look at what makes certain rivets well-suited for CNC riveting applications. We’ll also overview recommended rivet types, alloys, coatings, and other factors to consider when selecting rivets for a CNC process. With the right knowledge, manufacturers can make informed choices when sourcing rivets for their automated production lines.
Desirable Qualities in Rivets for CNC
For smooth automated riveting, rivets must possess certain physical characteristics. Here are some of the most important qualities CNC rivet manufacturers look for:
- Consistent sizing - Rivet diameters must adhere tightly to stated tolerances, usually +/- .001 inches or less. Rivets that vary too much in size can jam feeder tubes or fail to set correctly.
- Round shanks - Shanks should be highly cylindrical without flat spots or irregular shapes that impede feeding.
- Chamfered ends - A slightly rounded end chamfer facilitates automated feeding into riveting tools.
- No burrs or defects - Flaws like cracks, pits, or burrs on the rivet shank can inhibit smooth setting.
- Tight head/shank intersections - Heads should transition neatly into the shank without undercuts or right angles that impact setting.
- Concentric heads - Rivet heads must be precisely centered to avoid irregular joints.
- Correct hardness - The rivet alloy should be hard enough to set without distorting, but not so hard it becomes brittle.
- Tight tolerances - All dimensions should adhere to stipulated tolerances to ensure consistency.
Leading rivet manufacturers subject their products to rigorous quality control measures including visual inspections under magnification, dimension analyses with calibrated instruments, and functional tests to guarantee CNC-grade rivets meet these demanding standards.
Alloy Considerations for CNC Rivets
The alloy the rivet is made from directly affects its strength, hardness, and setting performance. Here are some top alloy choices for CNC rivets:
- 2117 aluminum - Offers excellent machinability, strength, and corrosion resistance. It's one of the most popular alloys for aircraft rivets.
- 2024 aluminum - This high-strength alloy provides superior fatigue resistance for heavy-duty joints.
- 7075 aluminum - Rivets made from this ultra-high strength alloy are ideal for high shear applications.
- A286 stainless steel - Combines excellent strength with corrosion resistance for lasting joints.
- Grade 8 high-strength steel - Its high hardness allows joints with superior shear and tensile strength.
- Monel nickel-copper - Offers the strength of steel with added corrosion resistance.
The desired joint strength, environmental factors, disassembly requirements, and other application-specific criteria will guide alloy selection for a CNC riveting project. Consulting with a qualified rivet supplier is advisable when choosing an alloy.
Rivet Head Styles for CNC
Rivets come with a variety of head shapes suited for different installation methods and joint types. Here are some top head style options for CNC riveting:
- Dome head - A rounded dome shape that provides excellent flow into the riveting die. Recommended for most CNC applications.
- Oval head - Similar to dome but with an oval profile. Offers greater clamping force than dome heads.
- Countersunk head - Flat, tapered head for flush setting into countersunk holes. Popular for aircraft skins.
- Universal head - Combines a domed top with a flat bottom permit flush or protruding installation.
- Flat head - Cylindrical flat top for low-profile joints. Not suitable for high strength joints.
- Truss head - Extra wide dome for greater bearing area and shear strength.
- Button head - A decorative convex shape for smooth, finished appearance.
The joint design and end-use determines proper head configuration. CNC-rated rivets are stocked in these styles from quality vendors. Custom head designs are also available for specialty applications.
Rivet Coatings and Treatments
Special coatings and surface treatments can be applied to CNC rivets to enhance certain properties:
- Anodizing - An oxide layer improves corrosion and chemical resistance. Available in clear, dyed, and Teflon impregnated versions.
- Epoxy - Thin epoxy coatings provide outstanding corrosion protection for steel rivets. Withstands solvents and chemicals.
- Zinc plating - Electroplated zinc coatings on steel rivets increase corrosion resistance. Offered in clear, yellow, and olive drab green.
- Passivation - Removes free iron from stainless steel rivet surface to boost corrosion resistance. Leaves a thin protective chromium oxide layer.
- Lubricity coatings - Dry film coatings like molybdenum disulfide lower friction for easier feeding through tooling.
Special processing like anodizing does add cost. Evaluate whether the added benefits justify the upcharge based on environmental exposure and expected part life.
Sourcing High Quality CNC Rivets
Shopping around helps find the best source for CNC-grade rivets tailored to your specific application. Here are some things to look for:
- Specializes in rivets for automated installation - This expertise ensures the product is purpose-built for CNC.
-Wide range of materials, finishes, and head options - Allows dialing in just the right rivet specification.
- Stringent quality control standards - Upfront quality saves headaches and downtime down the road.
- Large production capacity - Helps ensure availability of sufficient supply.
- Custom design/engineering assistance - Some vendors can help design a specialty rivet if needed.
- Competitive pricing on large orders - Big quantity buys should net discounted per piece pricing.
- Local warehousing/quick fulfillment - Speeds delivery so rivets arrive when needed.
With critical factors like consistent sizing, smooth feeding, optimized alloys, and controlled tolerances, not every rivet is suitable for CNC machinery. Partnering with a qualified supplier of rivets purpose-built for automated riveting helps manufacturers realize the full benefits of CNC through precision, repeatability, and peak joint integrity. Investing in quality rivets lays the foundation for maximizing CNC productivity and part quality. CNC Milling