Riveting in Sheet Metal Fabrication(snap joints Ternence)
- source:GAENOR CNC Machining
Sheet metal is one of the most common materials to be joined by riveting. The thin metal sheets used for applications like ductwork, enclosures, aircraft skins, etc. can be efficiently and securely fastened with rivets. Understanding proper rivet joint design, rivet types and installation methods is key for successful sheet metal riveting.
Benefits of Rivets for Sheet Metal
Compared to other mechanical fastening methods like welding, bolting or adhesive bonding, riveting offers numerous advantages for joining sheet metal:
- Speed - Automated riveting is extremely fast compared to manual welding or bolting. High production rates possible.
- Strength - Properly designed riveted joints can withstand high shear, tensile and bending loads.
- Consistency - Quality controlled automated riveting ensures consistently secure joints.
- No Heat Affected Zone - Unlike welding, riveting doesn't alter material properties surrounding joint.
- Electrical Conductivity - Rivets allow electrical current flow across a joint, unlike adhesives.
- Disassembly - Rivets can be removed to separate material later if needed. Permanent joints like welding are difficult to take apart.
- Appearance - Countersunk rivets provide a smooth finished surface appearance.
Proper rivet selection, joint design, hole preparation and installation technique are critical for achieving optimal performance when riveting sheet metal.
Rivet Types for Sheet Metal
There are several types of rivets suitable for joining thin sheet metal:
Solid/Dome Head Rivets:
- Provide high shear strength. Most common type used for sheet metal.
- Available with various head shapes - dome, countersunk, large flange, etc.
- Installed by bucking (upsetting tail) or with seller/upsetter.
- Also known as pop rivets. Tubular body rivet with mandrel.
- Set from one side without access to back of sheet.
- Common types: pull (break) mandrel, flare mandrel.
- Combined punch and rivet setting tool.
- Pierces top layer of sheet and locks into bottom layer.
- No hole pre-drilling necessary. Fast installation.
- Used for structural steel connections. Very high shear/tensile strength.
- Bulbed cherry, large flat head, countersunk head styles.
- Set with powerful impact hammer tools.
Rivet Material Selection
Most rivets used for sheet metal fabrication are made from aluminum or steel alloys. Material is selected based on strength, corrosion resistance, appearance and cost requirements:
- Aluminum - Lightweight, corrosion resistant, softest option. 2xxx and 7xxx alloys common.
- Mild Steel - Strong, low cost material. Used for uncoated applications.
- High Strength Steel - Highest strength option. Ideal for structural connections. Can rust if unprotected.
- Stainless Steel - Highly corrosion resistant. Adds cost but improves appearance and longevity. 300 series common.
- Copper, Brass, Monel - Used for specialized corrosion resistance needs. Mostly for marine environments.
Proper Rivet Joint Design
Well engineered rivet joint design is crucial for achieving sufficient load capacity. Important design factors include:
- Rivet Diameter - Larger rivets provide greater joint strength. Must balance cost and performance.
- Sheet Thickness - Thicker material requires larger, longer rivets. Consider material stackup at joint.
- Spacing & Pitch - Rivets must be adequately spaced for load distribution without tearing sheet.
- Edge Distance - Sufficient distance from sheet edge avoids edge tearout under load.
- Rows & Stagger - Multi-row rivet patterns properly distribute load across joint.
Riveting Sheet Metal Successfully
Correct hole preparation, rivet selection and installation is key to creating secure sheet metal rivet joints:
- Drill holes to precise diameter, straightness and location. Clean holes.
- Select proper rivet material, diameter and grip length for application.
- Use quality riveting tools matched to rivet size and type. Proper force is critical.
- Buck or upset tail precisely to form shop head. Avoid damage to materials.
- Set rivets straight and completely fill holes. Remove shallow/cracked rivets.
- Stagger rows, space adequate edge distance, meet minimum pitch.
- Visually inspect set rivets. Confirm tight fit, full heads, consistent appearance.
- Deburr inside holes and underside of joints to prevent cutting hazards.
Properly riveted sheet metal joints can provide decades of reliable performance across countless industrial applications. When sound engineering practices are followed for design, material selection, hole preparation and rivet installation, optimal strength and longevity can be achieved. Automated riveting systems combined with skilled technicians makes the process highly repeatable for mass production needs. Riveting remains a versatile, efficient and cost-effective choice for permanently joining sheet metal components. CNC Milling CNC Machining