Riveting in Sheet Metal Fabrication(metal fabricating near me Delia)

  • Time:
  • Click:14
Rivets are a common and effective way to join pieces of sheet metal together. They create strong, permanent joints between overlapping or abutting pieces of metal. Riveting has been used for centuries in metalworking and remains an essential process in modern sheet metal fabrication.
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 through holes in the parts to be joined. The tail end is then upset, or mushroomed out, forming a second head. This process clamps the rivet in place permanently joining the parts.
Rivets are available in many materials, sizes and styles to suit different applications. Some common types include:
- Solid/Round Head - A basic rivet with a domed head. Used for general applications.
- Countersunk Head - Has a flat, flush head for applications where minimal protrusion above the surface is desired.
- Large Flange Head - Has an oversized flange for extra surface contact. Used when vibration could cause standard rivets to fatigue and fail.
- Blind Rivets - Rivets that can be installed from one side when access to both sides is limited. The mandrel stem is pulled to expand the blind side.
- Pop Rivets - Quick and easy blind rivets where the stem is popped off after installation. Used for temporary repairs or lightweight joints.
Riveted Joints
Rivets create permanent joints by physically deforming to fill hole clearances. This deformation also upsets the surrounding materials, placing them in compression. This is what gives riveted connections their strength and vibration resistance.
Some common types of riveted sheet metal joints include:
- Lap Joints - Two overlapping sheets joined with a single row of rivets. Simple but prone to fatigue.
- Double Lap Joints - Improved version with two overlapping rows of rivets, allowing for load distribution.
- Butt Joints - Two sheets meeting edge-to-edge, secured by a single row of rivets. Requires back-up strips for structural use.
- Strapped Butt Joints - Butt joint with multiple joining strips riveted over the seam. Removes need for back-up strips.
Benefits of Riveting
Compared to other mechanical fastening methods like welding and bolting, riveting offers several advantages:
- Permanent - Once installed, solid rivets cannot come loose or detach.
- Vibration Resistant - Riveted joints maintain integrity under shaking loads better than threaded or welded connections.
- No Heat Affected Zone - Process does not alter the microstructure of base materials like welding does.
- Allows Dissimilar Materials - Can join different metals without metallurgical issues.
- Easy Visual Inspection - Missing or defective rivets can be easily spotted for quality control.
- Lower Skill Requirement - Basic riveting can be learned quicker than welding or precision machining.
Riveting Process
Riveting sheet metal components together is a straightforward process that can be done manually or using specialist tools. Here is an overview of the riveting process:
1. Component Preparation
- Sheet metal parts are fabricated and holes drilled to specification. Hole diameter depends on rivet size.
- Parts are clamped or fixtured to align holes prior to riveting.
2. Rivet Selection
- Select rivet material, head style, diameter and grip length based on application requirements.
- Grip length needs to span total thickness of parts being joined plus clearance.
3. Hole Preparation
- Holes are deburred to allow rivet insertion. Countersinking may be required for flush head rivets.
- Temporary fasteners or adhesives help alignment during riveting.
4. Rivet Insertion
- Rivet shaft is inserted through holes until head contacts surface.
- Riveting hammer, press or squeezer is used to upset tail end and form second head.
5. Inspection
- Rivets are checked for head shape conformity, grip length and any cracks.
- Integrity of joint is checked with dyes, penetrants or other NDT methods.
Riveting Equipment
Driving rivets can be accomplished using simple hand tools but for productivity automated equipment is preferred for mass production:
- Riveting Hammers - Either manual or pneumatic hammers to upset rivets. Allow access for riveting in tight spaces. Limited production speed.
- Rivet Guns - Faster pneumatic, electric or battery powered tools designed specifically for blind rivets. Popular for aircraft assembly.
- Riveting Presses - Hydraulic or pneumatic presses that use pressure to upset rivets. Come in C-frame bench models or large floor models.
- Orbital Riveting - Spindle with off-center cam rotates rivet setter in small circles to form head. Fast technique used in auto panels.
- Robotic Riveting - Programmable robots that can rivet with consistency suited for high volume assembly lines.
Riveting Tips
Here are some useful tips for best results when riveting:
- Use rosin mild flux-coated rivets for aluminium to prevent oxidation.
- Blind rivets require access to only one side but have lower strength than solid rivets.
- Apply mild soap solution as lubricant to make driving the rivet easier.
- Use proper rivet setter shape - flat, concave, convex etc. to suit rivet head profile.
- Firmly hold parts together and check alignment before driving rivets.
- Ensure rivet fills hole and clamps parts without being overdriven.
- Stagger rows of rivets uniformly to distribute load across joint.
- Inspect for cracked, chipped, misformed or undersized rivet heads indicating bad rivets.
- Consider using washers under rivet heads for softer materials or thin sheet metal.
Riveting remains a simple, reliable and cost-effective method of joining sheet metal that continues to find widespread use in industrial fabrication. With an understanding of joints, equipment and techniques, high quality riveted connections can be achieved. CNC Milling