Producing High Quality Rivets with CNC Machinery(types of rivets Madge)
- source:GAENOR CNC Machining
What Are Rivets?
A rivet is a mechanical fastener that connects two or more materials by inserting a metal shaft through aligned holes in the materials and forming a head on each end. The rivet shank fills the holes and the formed heads securely clamp the materials together. Rivets come in a wide range of shapes, sizes and materials for diverse applications.
Benefits of Quality Rivets
Superior rivets are strong, consistent and reliable. Quality rivets made of hardened steel minimally deform when properly set. They maintain clamp load to prevent joint slippage and withstand shear and tensile stresses. High end rivets properly fill hole dimensions and have heads that uniformly bear on materials joined for maximum holding power. Quality rivets are durable, corrosion resistant and do not loosen over time. Using top notch rivets ensures products assemble correctly and safely perform as designed.
CNC Machining for Precision Rivets
Computer numerical control utilizes programmed computer software to direct machining tools. CNC enables fast, accurate and repeatable manufacturing. Various CNC processes can produce rivets with precision components not attainable with manual equipment. Benefits of CNC rivet production include:
- Tight dimensional tolerances - CNC machining precisely controls diameters, lengths, head height and other critical specifications.
- Excellent consistency - CNC automated programming reduces variations between rivets for uniformity.
- Complex geometry capabilities - CNC can mill rivet heads and shanks in almost any geometric shape.
- Smooth surface finishes - CNC machining provides fine surface finishes for reduced friction and improved appearance.
- Efficient high volume runs - CNC produces rivets rapidly for economical high quantity production.
- Flexible mixed size batches - CNC equipment can readily switch between different rivet designs and sizes.
- Automated in-process inspection - Automated gauging after milling ensures every rivet meets standards.
Rivet Materials for CNC Machining
The material used for a rivet significantly influences its performance and manufacturability. Common rivet materials compatible with CNC machining include:
- Aluminum - Lightweight and corrosion resistant but lower shear strength than steel. Often used for non-structural connections.
- Stainless steel - Stronger than aluminum and highly corrosion resistant, making it suitable for harsh environments.
- Carbon steel - Very strong but prone to corrosion. Carbon steel rivets have excellent clamp load retention. Often plated or coated for added corrosion protection.
- Copper - Used for electrical conductivity and corrosion resistance. Softer than steel and deforms more during riveting.
- Monel - A nickel alloy that maintains high strength and toughness in high temperature, pressure and corrosive environments.
- Titanium - Extremely strong but light rivets valued in aerospace applications. Challenging material to machine and expensive.
CNC Milling Rivet Shanks and Heads
The shank and head geometries of a rivet determine how it fits into materials and fastens them together. CNC milling machines can produce rivet shanks and heads to exactly meet application requirements.
Rivet shanks are usually cylindrical and precision milled to tight diameter tolerances. Common shank features easily machined with CNC include:
- Straight, uniform diameters.
- Multiple diameter steps along the length.
- Grooves for sealing rings.
- Angled shank ends to facilitate insertion.
- Threads for mating with threaded parts.
CNC milling can create rivet heads in many shapes, such as:
- Round domed heads - Provide good clamping force distribution.
- Countersunk heads - Sit flush with material surfaces.
- Low profile heads - Where a compact head height is needed.
- Large surface area heads - Maximize load bearing surface.
- Custom shaped heads - Match mating components or facilitate tool engagement.
Secondary CNC Machining Operations
In addition to milling shanks and heads, CNC enables other automated processes to enhance rivet production. Secondary CNC operations may include:
- Drilling cross holes - Holes perpendicular to the axis add retention strength.
- Tapping threads - Threads in the shank improve grip and allow bolt-like fastening.
- Grooving/knurling - Grooves and knurls for sealing, retention and ergonomic grip.
- Heat treating - Precisely heating and quenching at CNC workstations to harden rivet materials.
- Plating/coating - CNC handling allows high volume automated plating, anodizing, galvanizing and other finishes.
- Laser marking - Permanently laser etch identification, branding or markings on each rivet.
- Metrology - Automated in-line gauging for diameter, lengths, head dimensions and other critical measurements.
Rivet Design Considerations
To produce optimal rivets on CNC equipment, designers should:
- Use stronger, more machinable materials - Select metals and alloys like steel, aluminum and titanium over brass, plastic or rubber.
- Design rivets to be milled axially - Avoid complex multi-axis machining requirements.
- Minimize secondary processing steps - Limit extra drilling, threading and other ops for efficiency.
- Standardize models and sizes - Streamline programming and setup by minimizing unique designs.
- Design heads/shanks for balanced strength - Don't over or under design either component.
- Consider hardware requirements - Account for washers, grommets, seals and any other assembly components.
CNC machining provides unparalleled accuracy and speed for producing quality rivets suited to high demand manufacturing. Capable equipment programmed by experienced operators can mill rivet components and perform secondary operations for precision parts meeting critical application needs. By leveraging CNC capabilities, manufacturers can reliably produce perfectly formed rivets in any required material, size and design. CNC Milling CNC Machining