Choosing Quality Rivets for Your CNC Manufacturing Needs(non ferrous Elliot)
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- source:BAGANZ CNC Machining
Material Composition
The material used to make rivets directly impacts their strength, corrosion resistance, weight, and suitability for different applications. Common rivet materials include:
- Aluminum: Lightweight yet strong, aluminum rivets offer high strength-to-weight ratio. They have good corrosion resistance and conductivity.
- Steel: Stronger than aluminum but heavier, steel rivets provide high shear and tensile strength. They are prone to rusting unless properly coated.
- Stainless steel: More corrosion resistant than regular steel while maintaining strength. Stainless steel rivets are a good choice for harsh environments.
- Copper: Copper rivets conduct heat and electricity efficiently. They are softer than steel and can deform under high stress.
- Monel: A nickel-copper alloy that is very corrosion resistant while still fairly strong. Monel rivets work well in marine environments.
- Titanium: Extremely strong yet lightweight, titanium rivets are suitable for high-stress aerospace applications. They resist corrosion and can withstand high temperatures.
The particular material you choose will depend on the level of strength, weight, corrosion resistance, and conductivity needed as well as cost considerations. Consulting a qualified rivet supplier can help determine the optimal material for your application.
Manufacturing Process
How the rivets are manufactured also affects the consistency and quality of the finished product. There are a few common manufacturing processes:
- Cold heading: Using specially designed dies, cold heading forms the rivet head and shank without pre-heating. This allows for faster production of large batches.
- Hot forging: The metal is heated to make it more malleable before forming the rivet shape with dies. Hot forging can produce stronger parts.
- CNC machining: Highly precise CNC machines cut rivets from metal rods or tubes. This method allows for custom shapes and high accuracy.
- Casting: Molten metal is poured into molds to form rivet heads and shanks. Casting yields less consistent results than mechanical processes.
CNC machined and cold headed rivets offer dimensional precision vital for quality control. Opting for rivets made using these methods can ensure consistency between batches. The manufacturing process should use proper techniques to prevent defects.
Dimensions and Tolerances
When ordering rivets, carefully check critical dimensions like shank diameter, head height, head diameter, hole size, grip range, and overall length. The tolerances, or acceptable variance from the specifications, should adhere to your design needs.
Tighter tolerances on dimensions allow for more precision when riveting parts together but are more difficult to achieve in manufacturing. Looser tolerances will be easier to fulfill yet can compromise fit and performance. A reasonable balance is ideal.
Key dimensions and tolerances to pay attention to:
- Diameter - +/- 0.005" to 0.015” tolerance typical
- Length - +/- 0.005” to 0.020” tolerance typical
- Grip range - +/- 0.005” to 0.010” tolerance typical
- Hole size - Close fit for rivet diameter, +0.002” to +0.005”
Consulting your rivet supplier on capabilities for dimensional accuracy and tolerances is advised when performance is critical.
Testing and Certifications
Reputable rivet manufacturers will have quality control testing procedures in place. Rivets should meet criteria for tensile strength, shear strength, pull strength, and salt spray corrosion resistance. The specific tests and certifications will depend on the rivet specs and intended use but may include:
- ASTM F2280 - Mechanical testing of blind rivets
- ISO 9227 - Salt spray corrosion test
- SAE J78 - Shear testing rivets
- ISO 1478/2398 - Tensile test methods
- RoHS, REACH compliance
Ask potential suppliers to provide documentation on their quality control practices and testing methods. Having rivets that meet major industry standards provides assurance on their performance consistency.
Finish and Appearance
The surface finish and appearance of your rivets may matter depending on visibility and environmental factors. Some options include:
- Plain steel - Prone to corrosion unless plated/coated
- Zinc plating - Basic corrosion protection but grey colored
- Chrome plating - Decorative shiny finish with moderate corrosion resistance
- Cadmium plating - Offers good corrosion protection but is being phased out due to toxicity
- Paint/powder coating - Wide range of color options, more durable than plating
Smooth, consistent finishes provide optimal clamp load on the joined materials. Defects like scratches, nicks, dents, cracks, and peeling plating should be avoided. Make your aesthetic needs and environmental operating conditions known when sourcing rivets.
By taking these quality factors into consideration when choosing rivets for your CNC operation, you can be assured of getting hardware that meets the demands of your specific manufacturing project. Consult with experienced rivet suppliers to select optimal materials, dimensions, tolerances, testing, certifications, and finishes. Investing in high-quality rivets will pay dividends in the performance and longevity of your finished products. CNC Milling