The Importance of Rivets in CNC Machining(torsion snap joint Edwiin)
- source:HAOYU CNC Machining
Key Uses of Rivets in CNC Projects
Joining Sheet Metal - One of the most common uses of rivets in CNC is for joining thin sheets of metal together to fabricate enclosures, panels, guards, and more. The thin material can be challenging to weld, so rivets provide a simple fastening method. The riveting process can often be automated on CNC machines to improve efficiency.
Aircraft Assembly - Rivets are extensively used in aircraft construction to assemble the various aluminum and titanium components. Riveting provides a very strong joint that can withstand the extreme forces and vibration experienced by aircraft. CNC machines drill perfectly aligned rivet holes and specialty tools upset the rivets.
Securing Guards & Covers - Sheet metal machine guards, covers, and shrouds are commonly secured with rivets. The rivets allow quick removal for maintenance access but won't vibrate loose over time like fasteners. CNC punching machines can rapidly punch properly spaced rivet holes for mass production.
Joining Dissimilar Metals - When joining metals with very different thermal expansion rates, rivets can prevent warping or cracking from welding. The rivets act as mechanical fasteners but allow the metals to expand/contract independently. CNC machines precisely control hole location to ensure proper rivet alignment.
Permanent Fasteners - In situations requiring a permanent, tamper-proof fastener, rivets are a good choice. The deformed rivet shaft cannot be removed without destroying the rivet. CNC automation allows selectively inserting permanent vs removable rivets.
High-Strength Connections - Certain rivet materials like steel and titanium can provide very high shear and tensile strength. These types of rivets are useful for critical structural joints. Precision CNC hole drilling ensures rivets seat properly.
Corrosion Resistance - Rivets are available in corrosion resistant materials like stainless steel and aluminum for use in harsh environments. Automated CNC processes can improve quality control when using these expensive materials.
Common Rivet Types Used in CNC
Solid Rivets - These are the most basic type consisting of a single rivet shaft that is upset during installation. They provide moderate strength at low cost.
Blind Rivets - Blind rivets can be installed from one side when access to the back is constrained. The mandrel shaft is pulled to upset the rivet.
Drive Rivets - These have a pre-formed head and are driven in using a tool that upsets the tail. Drive rivets are common in automotive panels.
Self-Piercing Rivets - As the name implies, these special rivets pierce through the material during installation forming their own hole. No drilling is required.
Multi-Grip Rivets - Multi-grip rivets use an expanding shaft design to accommodate varying material thicknesses. Only one rivet size is needed.
Structural Rivets - Structural rivets are large heavy duty rivets that can carry very high loads for critical joints. Material thickness can exceed 1/2".
Tubular Rivets - Tubular rivets have a hollow shaft that is rolled into a tubular shape during installation. This creates a very stiff connection.
Countersunk Rivets - These rivets have a flat circular head that sits flush with the surface for a smooth appearance.
Dome Head Rivets - In contrast, dome head rivets have a convex rounded head that withstands fatigue better.
How Rivets Are Used in CNC Machining
Drilling Holes - The first step is precisely drilling matched holes in the materials to be joined. CNC machining centers excel at this task with accurate, rigid drilling.
Deburring Holes - Any burrs or sharp edges around the holes must be removed or they can keep rivets from seating properly. Automated deburring tools speed the process.
Installing Rivets - There are several techniques for mechanically upsetting the rivets depending on the type. Pneumatic, hydraulic, and hand tools are common.
Inspecting & Testing - QC checks verify all rivets were correctly installed and meeting strength requirements through techniques like ping or torque testing.
Rivet Hole Preparation - In some cases holes must be deburred, countersunk, spotfaced, or otherwise prepared to suit the rivet type. Tool changers on CNC machines enable this.
Automated Feeding - For high volume production, CNC machines can use feeder tubes or robotic arms to automatically supply rivets to the inserter tool.
Rivet Removal - If rivets ever need removed for maintenance or rework, CNC machines can be programmed to precisely mill off the deformed end or drill out the shaft.
CNC Software for Rivets
Riveting applications require specialized software features to automate the complex process. Here are some common capabilities:
- Automatic hole alignment between parts
- Support for multi-axis contours and angles
- Collision avoidance for rivet guns and shanks
- Integration with rivet feeding systems
- Rivet library with parametric hole sizes
- Rivet installation sequence optimization
- Support for mixed rivet types in one program
- Simulation of rivet driving process
- Automatic safety block insertion
- Post-processors for rivet system communications
By taking advantage of software options like these, manufacturers can create advanced CNC riveting processes that minimize manual labor and improve quality control. The automation and consistency provided by CNC is critical for cost-effective riveting in high production environments.
In summary, rivets may appear like simple fasteners, but their proper selection and application is key to producing high-quality products in fields from aerospace to medical devices. Mastering CNC riveting processes provides access to a proven, versatile mechanical fastening technology that will continue playing a major role in manufacturing. CNC Milling CNC Machining