Producing High Quality Rivets with CNC Machining(riveting Jerome)
- source:BAGANZ CNC Machining
What are Rivets?
A rivet is a mechanical fastener that consists of two main parts - a smooth cylindrical shaft and a head. The shaft is inserted into holes in the parts being joined and the tail is upset, or deformed to create a second head. The force created flares the tail and clasps the materials together between the two heads, creating a solid connection.
Rivets come in many styles, sizes and materials like aluminum, steel, titanium and more. Common types include blind rivets, drive rivets, flush rivets and solid rivets. Blind rivets are popular for fastening thin sheets where access is only available from one side. Drive rivets are installed by hammering the pre-formed head to flare the tail. Flush rivets feature countersunk heads that sit flush within the material. Solid rivets have a pre-formed head on one end and must be bucked or hammered to form the second head.
Why CNC for Rivet Manufacturing?
Producing quality rivets requires machining precision and consistency across high volumes. This is enabled by CNC or computer numerical control. In CNC machining, the process is controlled by programmed computer instructions that direct the machine tools with pinpoint accuracy and repetition.
Benefits of CNC rivet manufacturing include:
- Consistent quality: CNC eliminates variance in human machine operation for consistent, high quality output. Rivets feature remarkably tight tolerances of +/- 0.002 inches for the shaft and +/- 0.005 inches for the head. CNC delivers this precision rivet after rivet.
- Complex geometries: CNC enables machining complex forms like multi-faceted rivet heads and asymmetrical shank designs not possible manually.
- Faster production: CNC performs rapid, automated machining for maximum output. CNC also enables lights out production without human oversight for 24/7 utilization.
- Material flexibility: CNC machines different exotic and high-strength materials like stainless steel, titanium and specialty alloys impossible to handle manually.
- Scalable production: CNC allows easy scaling of rivet production to meet large volume demands by simply running more programs.
CNC Rivet Manufacturing Process
Producing rivets via CNC machining involves three main steps:
1. CNC Milling of Rivet Blanks
The process starts with milling the rivet blanks - cutting the rivet shanks from rod stock to precise lengths. This is performed on a CNC lathe or screw machine pre-loaded with bar stock. The CNC lathe utilizes high speed rotation and precision cutters to accurately slice the blanks off the stock and convey for further processing.
2. CNC Heading to Form Rivet Head
The rivet blanks are then headed via a cold forging process to form the rivet head. Heading is performed on a CNC header that uses dies to precisely form each rivet head profile. The CNC header allows programming different rivet head geometries simply by changing the dies. This enables flexible production of various rivet designs on the same machine.
3. Heat Treating for Strength
Once headed, rivets undergo heat treatment to improve their strength characteristics. The rivets are batch processed through an oven or furnace at temperatures of 300-700°F depending on the material. This heat-hardens the rivets and creates a more uniform grain structure optimized for strength, ductility and performance.
Advanced CNC Machines for Rivet Production
Modern CNC technology has enabled faster, more capable rivet machining than ever:
- Faster spindles: High torque spindles reaching 10,000 RPM enable quicker blank machining.
- Multi-axis machining: 4 and 5-axis CNC enables complex head forming in a single operation.
- Automated material handling: Robotic material handling speeds loading/unloading and reduces labor.
- In-process inspection: In-process gauging ensures every rivet meets tolerance specifications.
- Networked production: Connected machine tools allow centralized monitoring and control.
Key Considerations for Quality Rivets
To produce rivets of the highest quality via CNC, key factors include:
- Raw material selection: Aerospace grade aluminum, titanium and alloy steels are common choices. The stock must have proper grain structure and cleanliness.
- Dimensional precision: Holding tight tolerances - +/- 0.002 inches on diameter, +/- 0.005 inches on head - ensures proper fit and function.
- Head formation: Heading process must evenly fill out the die impression and achieve 100% contact for maximum strength.
- Heat treating: Correct heat, soak times and cooling ensures optimal hardness, ductility and microstructure.
- Surface finish: A smooth uniform finish improves insertion, avoids material jamming and provides corrosion resistance.
- Testing and inspection: From raw material certifications to final QC, testing confirms rivet quality.
With attention to these factors, CNC machining delivers quality rivets for critical applications across aerospace, automotive, electronics and more. The precision of CNC is enabling the next generation of smaller, stronger and more capable rivets advancing manufacturing across industries. CNC Milling