The Importance of Using Quality Rivets in CNC Machining(what is a plasma cutter Mike)
- source:BAGANZ CNC Machining
What are Rivets?
A rivet is a mechanical fastener that consists of a cylindrical shaft with a head on one end. The shaft is inserted into pre-drilled holes in the materials being joined and the tail end is deformed, or "bucked," to create a second head. This fastens the rivet in place using friction and compression to join the materials.
Rivets come in many sizes, shapes, and materials like aluminum, steel, titanium, and more. Popular types include solid rivets, semi-tubular rivets, blind rivets, and drive rivets. The type used depends on the application requirements.
Advantages of Rivets in CNC Machining
Compared to other fastener types like nuts and bolts, rivets offer unique benefits for CNC machined parts and products:
- Speed of Installation - Rivets can be quickly installed with automated riveting equipment in CNC machining centers. This reduces production time.
- Vibration Resistance - The tight fit created by riveting provides excellent resistance to vibration and shock loads. This helps extend the life of products.
- Weight Savings - Hollow and semi-hollow rivets weigh less than comparable solid fasteners. This reduces weight in transportation equipment.
- Material Joining - Rivets can join dissimilar materials like metal alloys, plastics, composites, and more. This enables innovative product designs.
- Tamper Resistance - The peened tail of a rivet cannot be removed without drilling out the rivet. This makes rivets ideal for security applications.
- Economy - Rivets provide a cost-effective fastening method compared to welding, adhesives, or threaded fasteners in many cases.
The Risks of Low Quality Rivets
While rivets may seem like an insignificant part, low quality rivets can compromise the safety and durability of CNC machined products. Potential risks include:
- Poor Strength - Inferior rivets are more likely to suffer fatigue failure, come loose, or break under stress. This can cause catastrophic failures in machinery and equipment.
- Corrosion - Low quality materials and platings can corrode over time leading to rivet failure, lost clamp load, and joint deterioration.
- Improper Fit - Poorly manufactured rivets may not fit correctly into rivet holes leading to loose connections and misalignment.
- Excess Burr - Rough, sharp burrs left on poor quality rivets can damage parts, injure workers during handling, and make installation difficult.
- Out of Spec - Rivets that are out of specified tolerances won't install properly or perform as designed. Reject parts may be necessary.
Any of these flaws in inferior rivets used in CNC machined products can lead to costly rework, damaged reputation, and safety hazards if they fail.
Guidelines for Choosing Quality Rivets
Follow these guidelines when selecting rivets for your CNC machining applications:
- Reputable Supplier – Select a trusted rivet manufacturer with experience supplying the aerospace, defense, transportation, or other relevant industries.
- Certifications - Look for important quality certifications like ISO 9001 and AS9100 that validate the supplier's quality systems.
- Tight Tolerances - Precision engineered rivets within tight length, diameter, head, and other dimensional tolerances ensure proper fit and performance.
- Correct Materials - Match rivet materials like aluminum alloy or stainless steel to the strength, corrosion resistance, and compatibility needs of the application.
- Proper Platings - Zinc, cadmium, anodized, or other plated rivets resist corrosion in harsh environments.
- First Article Testing - Ask suppliers to provide sample rivets from the production lot for test fitting and quality validation before buying full volumes.
- Rivet Design - Consult with the supplier's engineers to select the optimal rivet style, head type, diameter, grip length, and other attributes for your specific application.
- Quality Certs - Require that rivet suppliers provide certificates of conformance, test reports, or other documentation to prove rivets meet specifications.
Following these guidelines helps ensure that the rivets you use in CNC machining meet the critical quality and performance standards for your applications.
Inspecting Rivets & Improving Quality Control
To further protect part quality, aerospace and other manufacturers implementing CNC machining should take measures to inspect rivets and improve quality control. Useful tips include:
- Statistical Process Control - Use SPC methods like random sampling and control charts to monitor variability in rivet dimensions and flag out-of-control production.
- Vision Inspection - Automated machine vision systems can quickly inspect for surface defects and measure dimensions on large volumes of rivets.
- Gauge R&R - Regularly audit inspection equipment like go/no-go gauges to ensure repeatability and reproducibility when checking rivets.
- Traceability - Confirm that suppliers provide lot traceability for the rivets they provide in case future defects require root cause analysis.
- Receiving Inspection - Visually inspect and measure sample rivets from each new batch upon receiving to verify they meet specifications.
- Staff Training - Provide regular training to inspectors, machinists, and assemblers on proper rivet handling, inspection methods, and quality documentation.
- Corrective Action - Work closely with suppliers to quickly identify, correct, and prevent any rivet defects that slip through to production.
Investing in quality rivets and robust rivet inspection delivers big rewards in minimizing production disruptions, recalls, and runtime parts failures in CNC machined products.
Proper Rivet Use Techniques
To get the full performance benefits of quality rivets in CNC production, employing proper riveting techniques is also critical:
- Hole Preparation – Use sharp drill bits and allow proper clearance to achieve clean, accurate, and uniformly aligned rivet holes.
- Surface Prep – Deburr, clean, and prepare joining surfaces to maximize rivet clamping force.
- Tool Selection – Choose the right rivet gun, setter, or pneumatic hammer with force control for the rivet size and application.
- Operator Skill – Develop operator proficiency through training and certification in best practices for rivet insertion, bucking, and inspection.
- Tool Maintenance – Follow preventive maintenance schedules to keep installation tools in optimized working condition.
- Hole Filling – Select the proper rivet length to completely fill holes after driving to maximize joint strength.
- Position Alignment – Use fixtures or careful manual handling to precisely align rivet positions between parts.
- Insertion Control – Use adequate force when seating rivets to sit flush without causing surrounding metal deformation.
- Bucking Method – Select appropriate single-sided or double-sided bucking methods to form symmetrical rivet heads.
- Stressed Areas – Increase rivet density in highly stressed or loaded areas to distribute force.
Properly driving quality rivets using these proven techniques will produce robust, long-lasting joints in CNC machined parts and assemblies.
From aircraft and defense systems to automotive, marine, and other industries, CNC machined products often rely on rivets for structural integrity. While small, low quality rivets can have disastrous and expensive consequences if they fail. By choosing reputable suppliers, implementing thorough inspection processes, and following precise riveting methods, manufacturers can count on consistently strong, reliable rivet joints in their machined products. The upfront investment in quality rivets saves money over the long run thanks to reduced rework, scrappage, and warranty claims. CNC Milling