Introduction(finishing metal Grace)
- source:CLAREY CNC Machining
Rivets come in a variety of types, sizes and materials to accommodate different design needs. Their versatility, ease of installation and durability make them a go-to fastening solution for CNC machined parts and assemblies across many industries.
In CNC machining, rivets serve both functional and aesthetic purposes. This article will provide an overview of common uses for rivets in CNC work, including joining dissimilar metals, attaching panels and hardware, rivet patterns for decoration, and more. We’ll also briefly cover rivet materials, styles and installation methods.
Joining Dissimilar Metals
One of the key advantages of rivets in CNC applications is their ability to join dissimilar metals. The friction, compression and mechanical interlock formed by riveting provides a solid joint without fused coalescence. This allows different metals to be mated in a way that welding or brazing cannot achieve.
Riveting dissimilar metals is commonly done to combine the unique properties of each material. For example, an aluminum housing can be riveted to a steel bracket to get the lightweight and corrosion resistance properties of aluminum along with the high strength of steel.
The joint integrity between dissimilar metals depends on proper material choice, hole size and rivet quality. Proper installation is also key, as uneven or off-center riveting can undermine the joint strength.
Attaching Panels and Hardware
In addition to joining metals, rivets are ubiquitously used to attach panels, covers, handles, brackets, and other hardware to CNC machined parts. Rivet installation is generally quick and straightforward, providing a permanent fastening method when components must be frequently removed and replaced.
Locating pins, pivot pins, hinges, and other detachable hardware are often riveted instead of screwed or welded in place. This allows them to be drilled out and replaced if needed, while avoiding thread wear or damage from reusing machine screws.
Rivets also provide enhanced shear and tensile strength over screws in joining panels, covers and other enclosures to a component body. The blind side of a rivet fills the hole for improved structure and appearance versus an exposed screw head.
Decorative Rivet Patterns
Beyond function, rivets are frequently used decoratively in CNC work to create textured patterns and designs on part surfaces. Rows of uniformly spaced rivets can achieve a high-end industrial aesthetic. Creative rivet patterns can also be used as company logos, model designations or other markings.
Decorative rivet heads come in various shapes like round, pan, countersunk and more. Head size, spacing and arrangement can be customized to achieve different artistic effects. Using rivets of different metals, such as brass, copper or steel, within the same pattern provides tonal variation.
In some cases, decorative rivet heads are machined off after installation to create a smooth, uniform peened surface. The resulting dimples provide visual interest and tactile texture.
The most common rivet materials used in CNC applications are aluminum, steel, stainless steel, copper and brass. Each material offers different strengths suited to specific uses:
- Aluminum: Lightweight, with good corrosion resistance. Common for aircraft and marine applications.
- Steel: High strength and low cost. Used for high-stress connections. Can be heat treated for enhanced hardness.
- Stainless steel: Best corrosion resistance. Ideal for exposed surfaces in harsh environments.
- Copper: Decorative look, with good conductivity. Used for electrical connections.
- Brass: Attractive gold color. Provides good corrosion resistance. Popular for decorative touches.
Several rivet styles are commonly used in CNC work:
- Solid/Round Head: Most common style. Round head with short cylindrical shank. Good shear strength.
- Countersunk Head: Flat head fits flush into countersunk hole. Provides a smooth finished surface.
- Pan Head: Shallow domed head with short cylinder below. Low-profile semi-flush surface.
- Button Head: Cylindrical head with a smaller diameter than shank. Can fill tapered holes.
- Flat Head: Low-profile flat circular head. Used where a flush surface is needed.
In addition to head shape, rivets come in “blind” and “through hole” shank types to suit different applications. Blind rivets are installed from one side using a rivet gun, while through hole rivets require access to both sides.
Installation techniques for different rivet types include:
- Solid rivets: Holes are drilled through the materials to be joined. Rivet is inserted and a rivet gun or hammer is used to flare out the protruding end.
- Blind rivets: Rivet gun draws mandrel into rivet body, flaring it to form blind head. Mandrel snaps off after installation.
- Self-piercing rivets: Pre-headed rivet is forced through materials without pre-drilling. Often used for sheet metal.
- Pop rivets: Jaws of rivet gun draw mandrel into body, then mandrel is released and pops off.
- Hammer-set rivets: Set by striking pre-formed head to flare opposite end. Requires access to both sides.
Proper hole sizing, rivet length and installation force are key to achieving optimal performance. Mechanical tests should always be conducted on sample joints to verify strength.
Rivets deliver versatile, reliable and cost-effective joining solutions for many CNC machining applications. Their ability to permanently fasten dissimilar metals, attach hardware, and provide decorative effects expands manufacturing capabilities beyond welding, screws or adhesives alone.
With the right rivet style, materials and installation method, CNC designers can take advantage of rivets’ mechanical strength, quick installation, and aesthetic customization to optimize machined part function while reducing assembly labor and costs. CNC Milling