Making Quality Rivets with CNC Machines(metal surface Lorraine)

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Rivets are a critical component in many manufacturing and construction projects. Though small, these metal fasteners hold together large structures from bridges to skyscrapers. For rivets to work properly, they must be high quality and precisely made. This is where computer numerical control (CNC) machines excel.
CNC machining uses programmed computer software to control the movements of machinery. This automated process allows for incredibly accurate and consistent production. CNC machines are ideal for manufacturing small, high volume parts like rivets. Here's an overview of how CNC technology is used to produce superior quality rivets.
Raw Material
The raw material for rivets depends on the intended application but is commonly aluminum, steel, copper, or titanium. The material must have the strength to withstand shearing forces but also be malleable enough to flare out and grip materials together. The raw stock comes in rods, wires, or bars.
CNC machining starts with this raw solid material loaded into the machine. Computer controls direct the cutting tools to precisely machine the material into the final rivet shape. This raw stock is held firmly in place while rotating cutting tools carve away excess material.
Shaping the Rivet Head
Rivets contain a head on one end that is wider than the rivet body. This head keeps the rivet from pulling back through pre-drilled holes. CNC machines utilize special shaped cutting tools to form the rivet head. The cutters are mounted on rotating spindles and move across the top of the raw material, carving a precisely shaped head.
For large diameter rivets, an initial roughing head cut is made to remove the bulk of material. Then a finishing tool makes a final pass to achieve the exact head dimensions. The automated programs control the depth and concentricity of the head cut. This ensures consistency across production runs.
Precision Cutting the Rivet Body
The rivet body is the straight cylindrical or tapered shaft that gets inserted into holes. CNC machines excel at cutting very precise diameters along a length of material. The computer controls the linear position and rotation of cutting tools to achieve an exact rivet body diameter.
Tolerances of just a few thousandths of an inch are held for the body diameter. This precision sizing allows the rivets to slide smoothly into pre-drilled holes before flaring out. Holding tight tolerances also improves fatigue performance by eliminating play or wobble during use.
Chamfering and Fluting
Rivets require additional shaping features beyond just the head and body. Chamfered edges help guide and center the rivets into holes during installation. Longitudinal flutes along the body give the metal room to displace, allowing the rivet to flare out and grip materials together.
CNC machining performs these secondary operations by controlling the angle and position of specialty cutting tools. The machines tilt, rotate, and precisely position the cutting edges against the edges and circumference of the rivets. This shapes the optimally designed features onto each rivet quickly and accurately.
Threading the Tip
Some rivets have threaded tips which allow a bolt to be screwed into the end. The threads provide a very secure hold and allow easy disassembly compared to hammering out solid rivets. CNC machinery can cut very precise internal or external threads along the end of the rivet body with coordinated rotating and linear motions.
Single or multi-start threads with fine pitches are no problem for CNC equipment. The computer programs move the threading tools steadily along the rivet tip while precisely rotating to cut clean and strong threads. This threading helps lock rivets in place and improves vibration resistance for critical applications.
Heat Treating
Once rivets are machined to shape, a heat treating process hardens and strengthens the metal parts. The rivets are heated in industrial furnaces to critical temperatures based on the material. They are then quenched rapidly in water, oil, or air to make the metal more rigid and resistant to shearing.
The automated material handling of CNC machines allows seamless integration with heat treating operations. Rivets can be efficiently shuttled back and forth between machining centers and furnaces for a continuous hardening process. This improves turnaround times and productivity.
Quality Control
Throughout the CNC machining and heat treating process, strict quality control is implemented. Dimensional tolerances are continuously checked using automated inspection probes. This verifies that the rivet heads, bodies, chamfers, flutes, threads, and all features are within specifications.
The quality department also regularly tests material hardness and tensile strength. They ensure the rivets meet requirements for shear strength, torque resistance, and service life. Any out-of-spec parts are rejected and production parameters adjusted to prevent future defects.
Rivet Insertion Methods
The small size and precision accuracy of CNC made rivets allows for efficient installation. Rivets are commonly inserted in pre-drilled holes by pneumatic squeezing or hammering the head. This flares out the body, permanently joining materials. Protruding threaded rivet tips can also be secured with nuts.
The flawless geometry of CNC rivets improves hole filling and clamping force. There is no variation part-to-part, so the installation system can be calibrated precisely. Lower friction from consistent diameters also reduces wear on insertion tooling. Altogether, the precision of CNC rivets results in faster, easier installation with tighter tolerances.
From raw material to final installation, CNC machines help produce flawless, high strength rivets. The automated precision of CNC machining creates rivets with consistent dimensions and optimized features not attainable with manual methods. This quality allows rivets to be manufactured in large volumes while performing reliably in critical applications. CNC technology brings together speed, precision, and flexibility resulting in the best possible rivet production. CNC Milling