Ensuring High Quality Rivets for CNC Machinery(metal parts manufacturing Hedy)
- source:WEINBERG CNC Machining
What Makes a Quality Rivet?
High quality rivets suitable for CNC machinery share the following characteristics:
Material - Aircraft grade aluminum is the most common material for CNC rivets. Aluminum provides high strength-to-weight ratio and corrosion resistance. Other options like stainless steel and copper may be used depending on the application.
Strength - Rivets come in various grip lengths and diameters to accommodate different material stackups. Selecting the right combination of dimensions is essential for a secure fastening. The rivet must be strong enough to handle shear and tensile stresses without buckling.
Precision - Quality rivets will have a tight dimensional tolerance. The shank diameter and length should adhere exactly to specifications. This ensures consistency and reliability in an automated CNC process.
Finish - A smoothly polished rivet surface reduces friction during installation and provides a flush final appearance. Deburring must eliminate any sharp edges or cracks.
Consistency - Trusted rivet suppliers will provide uniform hardness, composition and geometry from batch to batch. Variations in quality can lead to CNC fastening issues down the line.
Tests - Reputable manufacturers will rigorously test rivet mechanical properties and quality control. Certificates of compliance should confirm rivets meet required standards.
Choosing the right rivet specifications and supplier is step one. Proper techniques for automated and manual installation are equally important for achieving high quality and long-lasting riveted connections.
Automated CNC Riveting
CNC machines excel at automating high volume rivet installation. This process requires precision fixturing to index the parts and thoughtful programming to control the riveting sequence and forces. Here are some tips for optimized CNC riveting:
Fixture Design - Fixtures should locate parts securely while still granting rivet gun access. Minimal clearance around rivets is ideal. Clamps must keep components fully seated during installation.
Gun Selection - Rockwell, shear strength and material stackup thickness determine appropriate gun model and power. Optimal squeeze force uniformly compresses the joint. Too little force risks a loose connection while too much can damage parts.
Feeders - Vibratory bowl feeders oriented correctly ensure consistent rivet delivery to automated guns. Proper feeder angle, noise level and free flow of rivets prevent jams.
Sequence - The order of operations matters. Typically holes are drilled, deburred and countersunk prior to rivet insertion. The sequence and pattern of riveting can minimize distortion in panels.
Pressure Control - Sensors relay pressure feedback to the CNC controller. Adjusting squeeze parameters dials in optimal force and compression for different rivet locations in a program.
Process Validation - Test runs should confirm program outputs. Check for any missed or partially driven rivets. Fine tune pressure settings and dwell times until rivet quality is satisfactory.
With dialed-in processes, automated CNC produces highly consistent and secure riveted assemblies.
Manual Riveting Techniques
Many shops will still perform riveting manually for prototyping, low volume production or large parts not suitable for CNC. Proper manual techniques are essential for quality.
Hole Preparation - As with automated riveting, drill and deburr holes cleanly before rivet insertion. Countersinking is recommended for flathead rivets.
Tool Selection - Hand squeezers, impact rivet guns and pneumatic bucking bars cover a range of applications. Choose tools sized for the rivet diameter.
Gun Use - Hold the gun square to the workpiece when driving rivets. Apply steady pressure until the rivet head forms completely. Avoid tipping the gun.
Bucking - Bars support the backside to create closed rivet ends. Adequate pressure must be maintained without deforming parts. Use appropriate tip shapes.
Inspection - Confirm properly formed heads. Check for damage to the surrounding material surface. Reject and replace any questionable rivets.
Riveting by hand relies heavily on operator skill. Training and practicing proper technique produces flawless results.
In summary, quality rivets are only part of the equation. Using precision CNC programs and machines or skilled manual riveting delivers robust and consistent riveted assemblies. Paying attention to critical factors like material selection, controlled compression and process validation ensures success with any riveted CNC application. CNC Milling