Producing High Quality Rivets with CNC Machines(interference fit Helen)
- source:GAENOR CNC Machining
In this article, we’ll look at how CNC machines are used to produce top-notch rivets efficiently and accurately.
What are Rivets?
A rivet is a mechanical fastener that consists of two parts - a smooth cylindrical shaft and a head. The shaft is inserted into a hole through the parts being joined and the head is upset, peened, or bucked to form the second head. This creates permanent deformation securing the rivet in place using clamping force.
Rivets come in many sizes, materials, and head styles to accommodate different applications and installation requirements. Common materials include aluminum, steel, titanium, copper, and specialty alloys. The diameter may range from 1/16 inch to over 1 inch.
heads can be round, brazier, countersunk, flush, oval, universal, mushroom, and more. Rivets are often used with washers to distribute load.
Benefits of Rivets
Compared to other mechanical fasteners, rivets offer unique advantages:
- Permanent Assembly - Once installed, the deformed head prevents the rivet from being removed without destroying it. This creates a permanent locked joint.
- Vibration Resistant - Riveted joints can withstand vibration better than threaded fasteners which may loosen over time.
- Strength - The cold working during rivet setting enhances strength properties of the shaft material.
- Removeability - Rivets can be drilled out if necessary to disassemble parts later on.
- Lightweight - High strength-to-weight ratio, especially with aluminum rivets.
- Cost Effective - Relatively low part cost compared to welding or adhesives. Quick installation further reduces labor.
These qualities make quality rivets well suited for critical applications like aircraft, bridges, shipbuilding, rail cars, and pressure vessels.
CNC Machining for High Production Rivets
Manual rivet production with presses or hammers has largely given way to automated CNC machining which offers many advantages:
- Speed and Volume - CNC machines produce rivets at very high rates unmatched by manual processes. This facilitates mass production.
- Accuracy and Consistency - Automated precision machining ensures each rivet meets tight dimensional tolerances with minimal deviation. Rivet shafts and heads are uniform.
- Quality Control - CNC processes are programmed, controlled, and monitored by computer. This reduces human error and enforces strict QC standards for high rivet quality.
- Flexibility - CNC programs can accommodate different rivet sizes and head styles from one job to the next with minimal setup.
- Waste Reduction - Automation optimizes material usage and minimizes waste. Manual processes are less efficient.
- Worker Safety - CNC rivet production removes workers from physically demanding tasks in harsh environments. The machine does the hard work.
Rivet Manufacturing Process with CNC Machines
While production methods vary between manufacturers, here is a typical automated rivet making process using CNC technology:
1. Rivet Shaft Production
- Rivet shafts are cut from wire or rod stock by CNC lathes. Precision cutting tools produce uniform shaft lengths with tight length tolerances.
- CNC turning operations form the rivet shank diameter and radiused transition to the head.
- Shafts may be heat treated to obtain desired hardness and strength. This is done in computer-controlled ovens.
- Automated quality inspection checks shaft dimensions at high speed.
2. Rivet Head Formation
- Pre-cut shafts are fed into CNC header machines which cold form the rivet heads.
- Progressive header dies precisely shape the rivet heads in stages with extreme accuracy.
- CNC machines adjust head diameter, shape, height, and other variables per the program.
- Automated gauging confirms rivet head dimensions match specifications.
3. Finishing Steps
- Smaller rivets may be tumbled in CNC machines to deburr and polish the finished rivets.
- The rivets are automatically sorted and packaged in boxes or bags. Counting and checking verifies quantities.
- Inventory control software tracks production output and stock levels in real-time.
The extensive use of automated CNC technology eliminates variability while maximizing production volumes. This results in high quality rivets produced consistently in the quantities needed while minimizing human intervention. Quality assurance is built into every step.
Rivet Quality Considerations
To achieve maximum performance, quality rivets must meet these key criteria:
- Precise dimensional accuracy - Diameter, length, head height - must adhere to design specifications.
- Alloy consistency - Shaft and head materials should be homogeneous without flaws.
- Concentricity - Shaft and head are perfectly aligned and concentric.
- Surface finish - Smooth surface and edges ensures consistent installation.
- Hardness - Proper heat treatment and hardness for strength.
- Tight tolerances - Dimensional consistency from rivet-to-rivet.
- Visual defects - No dents, cracks, seams or other imperfections.
- Count and packaging - Accurate quantities without damage.
CNC-produced rivets consistently meet these stringent requirements to provide maximum joint integrity in critical assemblies. This gives engineers confidence when selecting rivets for strength and reliability.
From aircraft and bridges to appliances and computers, quality rivets provide reliable fastening strength to hold our world together. While rivet designs are simple, producing flawless rivets at high volumes using tight tolerances is complex. This is where automated CNC machining shines.
By utilizing precision CNC machines and quality-focused processes tuned for high volume production, rivet manufacturers can supply large quantities of rivets that exceed expectations. Tight process control and automation results in near-perfect rivets time after time. When failure is not an option, choose CNC-machined rivets for proven performance. CNC Milling CNC Machining