Riveting in Sheet Metal Fabrication(mismatch defect in casting Kyle)

  • Time:
  • Click:6
  • source:YESCOM CNC Machining
Rivets are a common and effective way to join pieces of sheet metal together. They create a permanent mechanical attachment that is strong, reliable, and cost-effective. In sheet metal fabrication, rivets allow for fast assembly of parts and structures while still maintaining structural integrity. Let's take a closer look at how riveting works and its key benefits.
What is a Rivet?
A rivet is a mechanical fastener that consists of two main parts - a smooth cylindrical shaft and a head. The shaft is inserted into pre-drilled holes in the materials being joined. The excess length of the shaft extends out the other side and is formed into a second head using a riveting hammer, squeezing the materials together. The deformation and flare of the rivet tail locks the rivet in place, creating a permanent joining of the materials.
Rivets come in three main types:
- Solid/Blind Rivets: The most common type, blind rivets are placed into a hole from one side. As the tail is formed, it flares against the blind side material creating the rivet head.
- Structural Rivets: Also inserted from one side. Requires access to both sides of material, as a bucking bar is used to flare the tail when hammering the head into shape. Creates a very rugged, stiff connection.
- Drive Rivets: Installed by driving the pre-formed head into the materials using force. No flaring or deformation needed. Fast installation but less holding strength.
Rivet Materials
The most common materials for rivets include:
- Aluminum: Lightweight yet strong, aluminum rivets are easy to work. Used for aluminum fabrication projects.
- Steel: Strong and durable suitable for high-strength connections. Best for steel fabrication. Can be heat-treated for added strength.
- Copper: Used for copper piping and joining dissimilar metals. Copper rivets are softer and non-sparking.
- Monel: Corrosion resistant nickel-copper alloy good for marine and chemical environments.
- Plastic/Nylon: Insulating lightweight rivets used in electronics and for dissimilar material fastening.

Benefits of Rivets for Sheet Metal
There are many advantages to using rivets for fastening sheet metal components:
Speed & Ease of Assembly: Riveting is fast and easy. Pre-punched or drilled holes allow fast alignment. Rivets can be quickly hammered into place for rapid connections. Minimal tools and training required.
Strength: The flaring of the rivet fills the hole and creates a tight joint. The mechanical interlock is very strong and resistant to shock and vibration forces. Holds well even under loads and impacts.
Durability: Once set, rivets form a permanent attachment that does not loosen over time. They have high fatigue life and can last the lifetime of the product. Rivets handle temperature changes and corrosion well.
No Adhesives or Welding: Rivets provide reliable fastening without the need for welding, gluing, or other joining techniques. This speeds assembly and reduces fabrication steps. The joint is visually inspected for proper setting.
Disassembly and Maintenance: Rivets allow for non-destructive disassembly if needed, using a drill to remove the rivet. This allows for repair, maintenance and part replacement when required. New rivets can be set to reassemble.
Appearance: The smooth finished head provides a clean uniform look. Countersunk rivets can provide a flush rivet head profile. Rivet heads can be painted to match the part's finish.
Cost Effective: Simple inexpensive tools make rivet installation affordable in any shop. Rivets themselves are low cost hardware, making riveting very economical for production runs.

Riveting Methods for Sheet Metal
There are several techniques used to rivet sheet metal components together:
- Hand Riveting: The traditional method uses a bucking bar on the passive side to flare the tail while the rivet set hits the head. Requires two people or a heavy bench fixture to absorb bucking bar force.
- Pneumatic Riveting: Uses pneumatic squeezing power to set the rivet. Allows one person operation. Access to both sides still required. Used for rapid production riveting.
- Impact Riveting: Battery powered rivet tools allow fast one-sided blind rivet installation. Portable tools for on-site assembly and repairs.
- Self-Piercing Rivets (SPR): Rivets pierce and join sheets in a single operation from one side. No pre-drilling needed. Great for mixed material connections.
- Press-Style Riveters: Use hydraulic or mechanical pressure to install solid rivets. Excellent for high strength structural joints. Limited shop applications.

Rivet Joint Design
Proper design of the riveted connection ensures maximum strength and durability:
- Hole Size: Holes should match the rivet diameter. Tolerance +/- .002 in. Larger holes reduce shear strength. Smaller holes make insertion difficult.
- Hole Spacing: Spacing between rivet holes should be 2-3 times the hole diameter. Closer spacing can cause metal failure between holes.
- Edge Distance: Holes should be 1.5-2 times the hole diameter from sheet edges. Maintains sheet edge integrity under load.
- Rivet Length: Length should allow enough tail material to flare and fill hole. Too short and joint strength is reduced. Too long can split sheet metal.
- Number of Rivets: More rivets distributes force over larger area for greater total strength. Rows of rivets may be staggered.
- Materials: Rivet material should match or be softer than the sheet metal material to allow flaring. Use rivet seals if leak prevention is needed.

Riveting Tips
Here are some helpful tips when riveting sheet metal:
- Use quality sharp drill bits for clean hole cutting. Deburr any sharp edges.
- Set rivets perpendicular to joined materials for even gap filling.
- Use smooth finished rivet heads for easier bucking bar contact.
- Select the rivet set for the rivet head size for clean impressions.
- Apply heavy pressure when starting to flare rivet tail. Continue hammering rivet head firmly.
- For blind rivets, pull slowly and allow rivet to set before breaking the stem.
- Visually inspect set rivet for full 360 degree flair and no cracks in rivet or sheets.
- Consider staggered rows for even load distribution in riveted assemblies.
- Be aware of techniques for special situations like riveting thin sheet metal.

Riveting is an extremely useful and reliable method of joining sheet metal components that every metal fabricator should understand. With the right joint design, tools, and techniques, rivets create strong permanent attachments perfect for countless sheet metal products and structures. The speed and simplicity of installation combined with the strength and longevity make riveting an essential manufacturing process. CNC Milling CNC Machining