Riveting in Sheet Metal Fabrication(cnc lathe machines Armand)
- source:YESCOM CNC Machining
What is a Rivet?
A rivet is a mechanical fastener that consists of two main parts - the rivet body and the mandrel. The rivet body is a cylindrical shaft with a head on one end. The mandrel stems from the opposite end of the body and is used to flare out the tail of the rivet body when setting it in place.
Rivets are inserted through pre-drilled holes in the sheets being joined. The tail end is then flared outward with the use of a riveting hammer, rivet gun, or other flaring tools to create a wide base that holds the rivet in place. The flared portion helps prevent the rivet from being pulled back out through the hole.
Benefits of Riveting Sheet Metal
There are several key benefits that make riveting a preferred joining method for many sheet metal products:
- Strength - The flared base creates a wide footprint to distribute force and prevent tear out. The joints can withstand high loads and vibration.
- Consistency - Automated riveting with pneumatic guns allows for consistent, repeatable connections. Riveting is less operator dependent than welding.
- Simplicity - Minimal equipment and training is required for basic riveting. The manual operation is straightforward.
- Flexibility - Some movement between riveted parts is permissible, preventing damage from shifts due to thermal changes or loading.
- Speed - Riveting is relatively quick compared to welding or screwing multiple fasteners. Automated tools further improve speed.
- Appearance - The smooth exterior surface of finished rivets makes for a clean, appealing look. Countersunk rivets can provide a flush final surface.
- Cost - Rivets themselves are inexpensive. Installation tools and labor costs are also low compared to welding or machining screws.
- Removability - Rivets can generally be drilled out if disassembly for repair or alteration is needed. This distinguishes them from permanent welds.
- Material Options - Rivets come in a wide range of metals, including aluminum, steel, stainless steel, copper, and more.
- Corrosion Resistance - Certain rivet materials, coatings, and finishes resist corrosion in harsh environments. Stainless steel and anodized aluminum rivets have excellent anti-corrosion properties.
When to Rivet Sheet Metal
Riveting is well suited for many sheet metal assemblies, though it may not be ideal for every application. Riveting sheet metal is recommended when:
- Permanent or semi-permanent fastening is required. For adjustable or temporary holding, other methods like nuts/bolts or screws may be better.
- Vibration resistance is important to prevent loosening of fasteners. Rivets withstand vibration well.
- Consistent quality is desired. Automated rivet installation provides repeatable results.
- Appearance is a consideration. The smooth exterior of flush rivets provides a sleek finished look.
- Cost reduction is a goal. Riveting is generally more affordable than welding or machined fasteners.
- Flexibility between parts is required to allow for thermal movement or loading shifts. Rivets allow some flexibility.
- Dissimilar or thin material sheets must be joined. Rivets can securely combine different metals or thin gauges.
- Overlap, edge, or blind joint locations prevent access for welding or bolt installation. Rivets can be applied from one side.
- Quick assembly speed is beneficial, as with high production rates. Riveting is fast compared to other methods.
- Removability for disassembly may be periodically required for maintenance or adjustments. Rivets can typically be drilled out if needed.
- Corrosion resistance is important. Certain rivet materials and platings, like stainless steel or aluminum, resist corrosion.
How to Rivet Sheet Metal
Once it is determined that riveting is the right choice for an application, proper techniques should be followed to create secure joints:
1. Select rivets of the appropriate type, material, length, and diameter for the sheets being joined. Larger sheets generally require larger rivets.
2. Determine the correct spacing for the rivets to distribute load across the joint. More rivets spread farther apart are needed for heavy loads.
3. Design hole locations and orientations that allow access for rivet installation tools and clearance for the rivet heads.
4. Use sharp drill bits suitable for the sheet metal thickness and material to produce clean, accurate holes. Deburr holes after drilling.
5. Apply sealant, adhesive, or tape on joint surfaces if needed to improve leak resistance or dampen vibration.
6. Clamp or fixture parts in proper alignment so holes match up across the joint during riveting.
7. Insert rivets through holes with heads on accessible side so they can be flared outward.
8. Use an appropriate riveting tool to flare out the tail, spreading it to 1.5-2x the shank diameter. Avoid damage to the surrounding sheet metal.
9. Inspect set rivets to ensure proper flaring and full shank contact with joint sheets to maximize strength.
10. Apply touch up finishes if needed to cover flared rivet tails and restore corrosion protection.
With the right rivets, tools, and procedures, riveting can produce professional quality sheet metal assemblies with strength, speed, and reliability. Understanding optimal uses and techniques helps fabricators take full advantage of this versatile mechanical fastening method. CNC Milling CNC Machining