Joining metal without heat
A rivet is a short metal pin with a head on one end. It passes through holes in the parts, and its other end is deformed so the parts are clamped together. Riveting needs no flame, arc or melted filler, so it is a good option when heat would warp thin metal, damage nearby finishes or cause a fire risk. It also avoids the fumes of welding and soldering.
Common rivet types
Blind rivets
Blind rivets, often called pop rivets, are the type most home users meet. They are set from one side only, which is the point of the word “blind.” A pop rivet has a hollow body and a thin stem, called the mandrel, running through it. When the rivet tool pulls the mandrel, the end of the rivet body behind the work swells and clamps the parts together, and the mandrel snaps off. The result is a neat, fairly flat head on the front and a flared end on the back.
Blind rivets are commonly made of aluminum, steel and stainless steel, among other materials. They suit sheet metal, brackets, enclosures, trim panels and similar light-duty work.
Solid rivets
A solid rivet is a simple shank with a head. It must be reached from both sides, with one side held against a support while the other end is hammered or squeezed to form a second head. Solid rivets make very strong, permanent joints and have a long history in structures such as old ironwork and aircraft. They require more skill and access.
Other forms
Structural blind fasteners, tubular rivets and several other styles exist for specialized purposes. If you work on anything critical, follow the maker’s instructions and applicable standards.
Tools
- Hand rivet tool. A plier-style tool with long handles that pull the mandrel. It is inexpensive and good for occasional use, though it can tire your hand if you set many rivets.
- Lever or heavy-duty hand tools. These give more leverage for larger rivets.
- Cordless and pneumatic rivet tools. Faster for repeated work. A pneumatic one needs an air compressor of suitable capacity.
Tools usually come with several nosepieces to fit different mandrel diameters. Match the nosepiece to the rivet.
Choosing and sizing the rivet
Two measurements matter: diameter and grip range.
- Diameter. It determines the size of the hole. A common approach is to drill the hole slightly larger than the rivet body, using the size the rivet maker recommends. A hole that is too large gives a loose joint, and one that is too small makes the rivet hard to insert.
- Grip range. This is the range of total material thickness the rivet can clamp. Add the thicknesses of the layers together and pick a rivet whose grip range includes that total. A rivet that is too short will not close the joint, and one that is too long may not set tightly.
The material of the rivet counts too. Pairing dissimilar metals, such as aluminum with steel, can promote corrosion where moisture is present, so consider the environment. Rivet makers’ charts provide guidance.
Setting a blind rivet
- Mark and center punch the hole locations, then clamp the parts together.
- Drill the holes through all layers at the correct size and deburr them. Burrs between layers keep the sheets from sitting tight.
- Insert the rivet through the holes.
- Seat the tool’s nosepiece on the mandrel, hold the tool square to the work, and squeeze the handles until the mandrel snaps.
- Check that the joint is tight and the rivet head sits flat.
If you need to drill out a rivet, use a bit about the size of the rivet body and drill just enough to remove the head, then punch out the remainder. A sharp bit that fits and slow speeds, as described in the article on drilling metal, help.
Strengths and limits
Riveted joints work well for:
- Thin sheet metal that would distort under heat.
- Dissimilar materials that cannot be welded together.
- Parts that do not need to be disassembled.
- Quick assembly with little equipment.
They are less suited to:
- Joints that need to be taken apart often. Bolts and screws, and the choices among fastener types, are better for that.
- Heavy loads in tension, where blind rivets are often weaker than bolts.
- Watertight or airtight seams, unless a sealant is used. Most blind rivets are not sealed by themselves, although some sealed types exist.
- Safety-critical structures, which should be designed by qualified people.
Safety
- Wear safety glasses. Mandrel stubs can fly off when they snap, and drilling throws chips.
- Keep fingers out of the path of the tool, and clear of the edges of the sheet metal, which can be sharp.
- Deburr the holes and trim any projecting mandrel pieces.
- Check the pressure rating and settings on any pneumatic tool.
Riveting is among the simplest joining methods to pick up, which makes it a sensible way for beginners to practice accurate marking, drilling and fit-up before moving on to heat-based processes.
This article is general information. Follow the manufacturers’ instructions for your tools and rivets.