Riveting in Sheet Metal Fabrication(gears Saxon)
- source:GAENOR CNC Machining
Rivets come in a wide variety of styles, materials and sizes to suit different applications. Some common types used in sheet metal work include:
- Solid rivets - These are made of a single piece of material like steel, aluminum, copper or monel. The rivet shank is inserted through the holes and a special tool is used to flare out the hollow end. This creates the second head that holds everything together.
- Blind rivets - These have a pre-formed head on one end and are perfect for when you only have access to one side of a joint. The shank is inserted through the holes and a pulling tool draws the mandrel stem to flare out the rivet body against the blind side sheet. The mandrel snaps off when set.
- Self-piercing rivets - As the name suggests, these cut their own hole rather than needing pre-drilled holes. Often used to join dissimilar or multi-layer materials.
- Structural rivets - Extra large and strong rivets designed for load bearing applications. Often have countersunk heads.
- Drive rivets - Also known as pin rivets. One end looks like a nail head and they are hammered in place rather than using a specialized setting tool.
- Pop rivets - Widely used lightweight rivets ideal for non-structural applications. Set by pulling the stem to snap off the mandrel.
Rivets offer numerous advantages that make them a popular choice for assembling sheet metal parts:
- They create very rigid joints without any play or loosening over time. The compression force of the set rivet holds everything tightly.
- Installation is quick and requires access only to one side (blind rivets). No need to hold parts together while setting fasteners.
- Minimal skill or training required for installation. A simple hand tool is all that's needed.
- Low cost, especially compared to welding or using multiple fasteners.
- Riveting doesn't damage protective coatings or weaken base metals through heat like welding can.
- Joints allow some flexibility and vibration dampening.
- Rivets are resistant to shock, vibration, temperature extremes, radiation and corrosion.
- Installation causes minimal distortion compared to welding.
- Riveted joints are easy to inspect visually. Loose rivets are obvious.
- Repairs only require drilling out old rivets and installing new ones.
- Rivets come in a huge range of sizes and materials to suit any need.
Of course, riveting does have some limitations to consider:
- Holes need to be precisely aligned for rivets to fit through. Fixtures are often required to hold parts in position.
- Only as strong as the base metals being joined (weaker than welded joints).
- Not recommended for sealing watertight joints.
- Permanent fastening method - parts can't be disassembled non-destructively.
- Riveting to extremely hard or brittle materials risks cracking them.
- Requires access to both sides of a joint (unless using blind rivets).
- Maximum material thickness is limited by rivet length.
The riveting process begins with designing and preparing the individual metal components to be joined. Parts are cut, formed and machined to specification, often using presses, rolls, brakes and CNC equipment. Sheet metal parts typically range from 20 gauge to 1/4" thick aluminum, steel, stainless or specialty alloys.
Holes are added using drills, CNC punching, laser/plasma cutting or other methods. Holes must align precisely between mating parts and match the rivet diameter. Design considerations like edge distances and spacing should follow rivet manufacturer recommendations. Clean deburred holes are essential for proper rivet seating.
Components are test assembled to check fit and locate any issues before final riveting. Parts are clamped in alignment jigs or fixtures to hold everything securely in place for riveting. Proper edge distances, spacing and orientation are double checked.
Now the riveting itself can begin. First, the correct rivet type and size is selected based on joint design, materials, strength needs and accessibility. Solid rivets require access to both sides. Blind rivets are inserted where only one surface is available.
Using a pneumatic, electric, battery or manual rivet tool, the rivet shank is inserted through the holes. The tool presses, squeezes or pulls on the rivet to deform it. This flares out the rivet body, forming a second head that clamps the materials together tightly. The pulling force can range from 100 lbs for small pop rivets to 15 tons for large structural rivets. It is critical the rivet is fully set to properly fill the drilled hole and maximize strength.
Riveting continues systematically across the joint until all holes contain a properly set rivet. Insp CNC Milling CNC Machining