High Quality Rivets Essential for CNC Machined Parts(riveted jewelry Roxanne)
- Time:
- Click:7
- source:GAENOR CNC Machining
What Makes a Quality Rivet?
Rivets are deceptively simple fasteners that consist of two main parts - the head and the shank. But high-performing rivets have some subtle design and material differences that distinguish them from lower-grade hardware.
Material - Aircraft-grade aluminum is the gold standard for CNC machined rivets. The aluminum alloy combines corrosion resistance, good conductivity, and high tensile strength. Steel rivets are very strong but prone to rusting. Other alloys like copper, magnesium, nickel, and titanium may be used for specialized applications.
Hardness - A rivet's hardness determines its shear and tensile strength. The optimal hardness balances strength with ductility to avoid becoming brittle. Hardness is measured on the Rockwell, Vickers, and Brinell scales. Quality rivets have a tightly controlled hardness rating.
Head Type - Several head designs are available like round, brazier, countersunk, modified brazier, and no-head styles. Pick heads suited for the part's assembly method and load dynamics. Round head rivets are versatile while countersunk heads provide a flush surface.
Shank Length & Diameter - Shank dimensions must be precisely matched to hole sizes. Too loose creates slop and too tight makes assembly difficult. Length depends on material thickness. Shanks come in 1/16” increments from 1/8” to several inches long.
Why Quality Matters
On the surface, rivets seem simple - just a pin that gets deformed on one end to cinch materials together. However, these inexpensive components see substantial forces in many applications. Using substandard rivets can lead to product failures, accidents, and injuries if they shear or pull out under stress.
Here are some reasons why quality rivets are mandatory for CNC machined parts:
Strength & Reliability - Aircraft, automobiles, appliances, and industrial machinery rely on thousands of rivets for structural integrity. Lax quality control and improper materials result in inconsistent hardness, shank dimensions, and head shapes that compromise strength. Well-made rivets reliably hold up to vibration, shock, and fatigue stresses over years of use.
Safety - When rivets fail, they fail catastrophically. Parts break free, mechanisms jam, and hardware tears loose. Weak rivets that were chosen to cut costs could result in accidents, damage, and liability claims. Consistently robust, high-quality rivets greatly improve safety margins.
Precision Assembly - Quality machinery merits quality fasteners. The tight tolerances and precision fits of CNC machined components require rivets that consistently match specifications. There is no room for variability with high-precision assembly.
Appearance - For finished products and exterior applications, the rivet heads must look neat, consistent, and professional. Pristine surface finishes, refined edges, and a clean, domed appearance are expected. Inferior quality control results in rough, malformed, or crooked rivet heads that cheapen the overall aesthetic.
Vibration & Shock Resistance - From using power tools to driving down rough roads, CNC machined parts must endure continual vibration forces. Lower grade rivets can gradually work loose, compromising the structure. Only high tensile strength, quality rivets stay secure and tightly fixed under adverse conditions.
Corrosion Resistance - Exposure to weather, chemicals, salt spray, cleaning agents, humidity, and condensation can corrode cheap steel rivets leading to staining, reduced strength, and premature failure. Stick with quality aluminum or stainless steel rivets for applications facing corrosion risks.
Inspecting & Testing Rivets
Trust but verify. To guarantee a batch of rivets meets specifications, manufacturers and consumers should perform several inspections and tests:
Dimensional Testing – Use precision tools like micrometers, scales, and calipers to check head diameter and shape, shank diameter and length, grip range, and other key dimensions. Verify critical angles and placement on specialty rivets.
Hardness Testing – Certified hardness testers perform superficial Rockwell, Vickers, or Brinell tests on samples. Hardness strongly correlates with tensile strength. Detailed coupons confirm hardness consistency through the batch.
Salt Spray Testing – Salt fog chambers simulate corrosive marine environments to check corrosion resistance. The samples withstand weeks of exposure before inspection. Minimal corrosion and rust confirm material soundness.
Shear Testing – A shear test exerts crosswise force on the rivet shank until it snaps. The force required to shear off the rivet is a key performance indicator. High values ensure rivets stay intact in products.
Tensile Testing – Tensile testing pulls the rivet head and shank in opposite directions until failure. It directly measures tensile strength for quality assurance.
Microscopic Inspection – Examine the rivet shank and head under magnification. Check for small defects like cracks, voids, impurities, misshapen head cavity, and other imperfections than compromise performance.
Only quality rivets that pass these stringent tests should be trusted for CNC applications.
Installing Rivets on CNC Machines
CNC machines automate and simplify the riveting process for large production runs. Here are some tips for riveting on CNC equipment:
CNC Code – The riveting sequence is programmed directly into the CNC machine code based on the locations of pre-drilled rivet holes. This ensures consistency across production runs.
Production Fixtures – Fixtures securely locate materials and components for consistent alignment of rivet holes. Robotic arms often manipulate the parts into optimal positions.
Automated Feeders – Rivet feeders connected to the CNC machine mechanically pick, orient, and place each rivet into the applicator for hands-free operation. Counters track usage.
Impact Rivet Guns – Pneumatic, hydraulic, or servo rivet guns mounted on the spindle precisely drive each rivet home using impact force. CNC controls the positioning, impact depth and angle.
Inspection & Sorting – Vision systems, sensors, and artificial intelligence automatically inspect installed rivets for any defects before removing the assembly from the CNC.
By integrating riveting tools into the CNC workflow, operators spend less time on menial tasks. The automation also improves quality and minimizes assembly errors.
Conclusion
From tiny electronics to massive aircraft, CNC machined products rely on thousands of robust, high-quality rivets. Their deceptive simplicity hides the strict demands of precision manufacturing. With scrutiny of materials, dimensions, hardness, surface finish, and performance, quality rivets play an outsized role in maintaining structural integrity, safety, and resilience. By selecting premium rivets and integrating automated riveting into CNC programs, manufacturers can streamline production while delivering exceptional products. CNC Milling CNC Machining