Riveting in Sheet Metal Fabrication(copper plated Beacher)

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Rivets have been used since ancient times to join pieces of metal together. While welding has become the most common method for joining metals, riveting is still an important process, especially in sheet metal fabrication. Rivets create a strong mechanical attachment that holds up well under stress.
In sheet metal fabrication, riveting is commonly used to join thin sheets of metal that may be challenging to weld. It is also useful when assembling pre-finished parts that should not be exposed to the heat of welding. Riveting creates a clean finished look without the uneven weld beads that can detract from aesthetic appeal.
How Rivets Work
A rivet is a short cylindrical rod that has a head on one end. The rivet is inserted into pre-drilled holes in the materials being joined. The plain end is then deformed so it swells up and locks the rivet in place. This is called the shop head or bucktail.
The shop head fills the drilled hole and clamps the materials together in a tight joint. The rivet head on the exterior side keeps the rivet from passing back through the hole. Rivets are commonly made from aluminum, steel, stainless steel, copper, and Monel.
Installation Methods
There are two main methods for installing rivets - hammering and squeezing. Hammering, sometimes called hand setting, uses a hammer and bucking bar to flare the rivet tail. Squeezing uses a rivet gun or specialized machine to apply pressure and flare the rivet.
Hammering is more labor intensive but allows access to joints where tools can't reach. It works best with softer rivets like aluminum. Squeezing is faster and more efficient, making it the preferred process for mass production. The pneumatic rivet squeezer can exert thousands of pounds of pressure to quickly flare any type of rivet.
Automated riveting machines are available for high-volume manufacturing. These machines feed and install rivets very quickly according to programmed settings. They can also add sealant during installation when a watertight joint is needed.
Rivet Styles
There are many different types and styles of rivets for various applications:
- Round head rivets are the most common type with a domed head.
- Countersunk rivets have a flat head that sits flush with the surface.
- Large head rivets provide a wider bearing surface.
- Oval head rivets are similar to round head but resist spinning.
- Truss head rivets have an extra-large flat head.
- Drive rivets have deep slots that accept a screw driver rather than a bucking bar.
- Split rivets can be installed blindly from one side.
- Structural rivets meet building codes for structural fabrication.
- Tubular rivets are hollow like a sleeve to provide extra grip.
Choosing the right rivet style is important for both appearance and function. Structural joints generally use solid shank rivets while split rivets work well for lighter assembly. The rivet material should match the metal being joined to prevent corrosion.
Riveted Joint Design
Proper design is critical for riveted joints that must withstand stress. Joints should be carefully analyzed to determine potential forces and load requirements. Rivets must be strong enough and spaced closely enough to handle expected loads.
General guidelines recommend at least three rivets per joint. The spacing between rivets should be around three times the thickness of the top sheet. For thin materials, a four times multiplier can be used. Minimum edge distance is 1.5 times rivet diameter.
Rows of rivets should be staggered rather than lined up. Lap joints should overlap by at least three times top sheet thickness. High-stress joints may require two or three rows of staggered rivets. Matching the drill size to rivet diameter ensures a snug fit.
Riveting Process
The riveting process involves three main steps - hole drilling, rivet insertion, and rivet flaring.
Drilling matched holes is critical for proper alignment. Holes must be round, straight, and sized correctly for the rivets. Deburring the holes helps prevent cutting the rivet.
Rivets are inserted through the aligned holes with the head on the accessible side. A bucking bar is held against the opposite end while the rivet shank is hammered or squeezed to form the shop head.
Proper flaring technique is important to spread the rivet tail and fill the hole without cracking. Rivet squeezers automatically control this through pressure, duration, and evenness.
Riveted joints should be visually inspected to ensure the rivet head and shop head are properly formed without cracks or deformities. Any bad rivets should be drilled out and replaced.
Benefits of Riveting
There are several benefits that make riveting advantageous for sheet metal fabrication:
- Riveting allows pre-finishing of parts before final assembly.
- It avoids concentrated heat affected zones caused by welding.
- Rivets accommodate some variation in hole size and alignment.
- Installation is simple and requires no special skills or equipment.
- Riveting is easily adapted for automation and mass production.
- It can join dissimilar metals more effectively than welding.
- Repairs usually just involve drilling out and replacing bad rivets.
- The flush smooth surface provides an attractive high-quality appearance.
While advanced welding techniques are now used for most metal fabrication, riveting remains an optimal choice for joining thin sheets, pre-finished parts, mixed metals, and assemblies where heat must be minimized. With the right joint design and quality rivets, it creates durable straight joints that can withstand substantial mechanical stress. Riveting will continue providing reliable and versatile metal fastening for sheet metal applications. CNC Milling CNC Machining