Quality Rivets - The Key to Precision Assembly in CNC Machines(kinds of spring Regan)
- source:YESCOM CNC Machining
What Makes a Quality Rivet?
High quality rivets suitable for CNC applications share several important traits:
Material - Aircraft grade aluminum is the most common material for CNC rivets due to its high strength-to-weight ratio. Stainless steel, titanium, and specialty alloys are also used for specialized applications. The material must be compatible with the parts being joined and able to withstand applied stresses.
Dimensional precision - Quality rivets have an extremely tight diameter tolerance, often within 0.001 inches. This ensures a tight fit without being oversized. Length is also tightly controlled.
Head shape - CNC rivets come in many head shapes like flat head, countersunk, oval head, and universal head. The head shape impacts fit, function, and automated feeding into CNC machines.
Grip range - The grip range refers to the thickness of materials the rivet can securely join together. Quality rivets grip tightly across their specified range to prevent looseness or movement.
Surface finish - A smooth surface finish allows quality rivets to slide smoothly during automated feeding. It also improves appearance for applications where the rivet head is visible.
Heat treatment - Proper heat treatment maximizes rivet strength and meets engineering specifications like shear strength and break load.
Testing/certification - Reputable CNC rivet suppliers test rivets to ensure they meet stated specifications. Qualified suppliers can provide documentation like test reports or manufacturer certification.
By paying close attention to these factors, CNC operators can select optimized rivets for their specific application requirements. This attention to detail improves overall quality and reliability.
CNC Riveting Techniques
CNC machines enable several techniques for precision rivet installation. Each has benefits suitable for different situations:
Blind rivets - Blind rivets can be installed from one side when there is only rear access to the workpiece. They use a pulling mandrel to expand the rivet body.
Solid rivets - Solid rivets require access to both sides of a workpiece. They are inserted and then a bucking bar keeps the material flush while a rivet gun forms the second head.
Self-piercing rivets - As the name implies, these rivets do not require pre-drilled holes. The force of the CNC machine presses the rivet through layers to be joined.
Friction stir riveting - This uses a rotating tool to heat and plasticize the rivet, allowing it to conform to the hole shape for a tight fit.
Automated feeding - For mass production, vibratory bowl feeders can orient and feed rivets into CNC machines for reliable high-volume riveting.
In addition to these techniques, CNC-specific tooling like precision rivet guns further improves the quality and consistency of automated riveting. Advanced machines even allow in-process inspection to verify every rivet meets specifications.
Quality Control for CNC Rivets
Given their importance, verifying rivet quality is imperative both before and during CNC riveting processes. Here are some of the techniques used:
Supplier qualification - Reputable suppliers have stringent quality control and supply documentation of rivet properties and acceptable tolerances. This provides assurance before rivets are even ordered.
Dimensional inspection - Sample rivets should be measured to confirm diameter, length, grip range, and other dimensional properties meet requirements. This can be done upon receiving a new rivet shipment.
Test assemblies - Test assemblies help qualify the performance of rivets when installed in real-world conditions. This validates properties like shear strength before full production begins.
Process monitoring - In-machine sensors coupled with statistical process control (SPC) software can track trends like rivet force. Operators can be alerted to investigate if any parameters fall outside expected limits.
Head shape inspection - Automated machine vision systems can quickly inspect 100% of rivet heads to confirm uniform and conforming head shape.
By thoroughly verifying quality at multiple points, CNC riveting processes can produce repeatable and reliable outcomes, preventing defects and improving end product performance.
Application Examples of CNC Riveting
CNC riveting shines in many manufacturing applications, including:
Aircraft assembly - CNC riveting machines excel at smoothly forming consistent, aerodynamic rivet heads to minimize drag. Riveting forms strong, lightweight connections between wings, fuselages, and other components.
Metal enclosures & frames - Electronics, appliances, furniture, and construction use CNC riveting to assemble durable metal enclosures and structural frames rapidly and securely.
Automotive components - Self-piercing rivets join layered materials like plastics, metals, and carbon fiber for car seats, door panels, and seat belts.
Jewelry and accessories - Small precision rivets make excellent pivots and hinges for jewelry and handbags. CNCs form perfect heads for decoration and branding.
Signage and decor - The CNC precision and consistency suits detailed decorative riveting for signage, public art, and architectural features.
In all cases, CNC-installed quality rivets outperform manual methods for speed, strength, precision, and repetition accuracy. As long as care is taken in rivet material selection and process validation, CNC riveting can mass produce assemblies with aircraft levels of quality and reliability.
While largely unseen, precision rivets join together and strengthen the products we depend on each day. By understanding critical rivet quality factors like material, dimensional precision, head shape, surface finish, and testing methods, CNC technicians can select optimized rivets for durable and reliable end products. With thoughtful supplier qualification, inspection practices, and process control, operators can have confidence in the consistency and structural integrity of CNC-riveted goods. The tiny rivet remains a key building block of modern manufacturing. CNC Milling CNC Machining