Rivets and Their Varied Uses in CNC Machining(snapfits Warner)
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Blind Rivets
Blind rivets, also known as pop rivets, are commonly used in CNC applications where access is only available to one side of the workpiece. The rivet body is tubular and has a mandrel through the center. Once inserted into the pre-drilled hole, the tail of the rivet is pulled via rivet gun, causing the mandrel to expand the body and create a permanent head on the blind side. The mandrel snaps off afterward. Blind rivets come in various materials, head styles, diameters, and lengths. Aluminum and steel are common choices, depending on strength needs and compatibility with the workpiece material. Countersunk head rivets allow for a flush surface on the exposed side.
Solid Rivets
Unlike blind rivets, solid rivets require access to both sides of the workpiece. They consist of a solid shaft that gets inserted into the pre-drilled hole before a head is hammered into place on the opposite side. This creates a permanent mechanical bond. Solid rivets can be used for heavy duty CNC projects and when vibration resistance is critical. The rivet heads also act as a structural support on thin materials prone to buckling. Stainless steel, aluminum, and copper are common solid rivet materials for CNC work, chosen based on required strength, corrosion resistance, and appearance.
Drive Rivets
Drive rivets provide an alternative to solid rivets when there is only access to one side of the assembly. They have a hollow body and solid mandrel, like blind rivets, but utilize a driver set to flare out the body rather than break off the mandrel. The flaring action spreads the tail end into a blind head inside the workpiece. Drive rivets are advantageous for CNC applications involving soft materials like sheet metals that could damage if hammering a traditional solid rivet.
Split Rivets
Split rivets consist of a tubular body that gets inserted into the pre-drilled hole. The unique split head permits insertion into confined spaces inaccessible to other rivet types. Once in place, the CNC operator uses a rivet setting tool to flare out the legs of the split head. This expands the body and creates a permanent mechanical bond. The flush tubular body is useful for smooth aerodynamic surfaces. Common materials are aluminum, steel, and titanium.
Tubular Rivets
Tubular rivets have a hollow body and are preferred for applications where minimizing weight is crucial. They can handle shear and tensile loads well despite the thin walls. In CNC applications, tubular rivets get inserted into the pre-drilled hole before the protruding shank gets upset and forged into a head using specialized pneumatic tools. The rivet gun both clamps the parts together and flares the tail. Flush heads allow for unbroken exterior surfaces. Aluminum is a common material, along with steel, copper, and brass.
Self-Piercing Rivets
As the name suggests, self-piercing rivets do not require pre-drilled holes. The semi-tubular body ends in a chisel point that punches through the top material when set. As downward pressure is exerted, the tail flattens inside the lower layer and creates a mechanical clinch. The flush exterior surface and speed of set-up make these ideal for automated high-volume CNC operations. Steel, aluminum, copper, and stainless steel self-piercing rivets are common.
Structural Rivets
Structural rivets are engineered specifically for load-bearing CNC applications where joins will undergo dynamic stresses. They have enhanced shear and tensile strength over general purpose rivets. The large, bulbous head provides exceptional support for structural members subject to compression, vibration, and shock loads. Common high-strength alloys include steel, aluminum, and titanium.
Custom Length Rivets
For unique CNC projects, custom length rivets allow precision joining of disparately sized materials. Instead of selecting a standard off-the-shelf rivet length, machinists can order specialty fasteners cut to a specific size. This ensures an optimum fit regardless of the rivet style used. It also permits improved control over grip length.
Rivet Nuts
Though not a true rivet, rivet nuts function similarly in CNC applications by creating strong threaded anchors. They consist of a tubular body with external threads and flexible wings. The nut gets inserted into a pre-drilled hole and a tool flares out the wings, locking it in place. This leaves durable machine screw threads accessible from the opposite side. Rivet nuts allow secure fastening of panels and hardware without having to tap threads into base materials too thin or fragile to withstand the torque.
In summary, rivets serve a vital role in CNC machining and manufacturing processes. The variety of types, materials, and sizes permits customized solutions capable of meeting diverse mechanical challenges. With sound understanding of the strengths and limitations of each option, CNC machinists can implement rivets in innovative ways across many applications. Whether used alone or alongside other fasteners, rivets will continue enabling precision joining and efficient fabrication. CNC Milling