Riveting in Sheet Metal Fabrication(delrin hardness Poppy)

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Rivets are a common and reliable fastening method used in sheet metal fabrication. They create strong permanent joints between metal components without requiring welding. Understanding when and how to use rivets for sheet metal assembly can help produce sturdier and more precise products.
What is a Rivet?
A rivet is a metallic fastener that consists of two main parts - the rivet body and mandrel. The body is a shaft with a head on one end. The mandrel stems from the opposite end and is used to flare out the body when setting the rivet.
Rivets are inserted through pre-drilled holes in the materials being joined. The setting process deforms the rivet body, pressing the materials together between the rivet head and flared end. This creates a permanent mechanical attachment.
Benefits of Riveting Sheet Metal
Riveting offers several advantages over other sheet metal fastening methods:
- Strong and Reliable Joints - The flare created by setting pulls materials tightly together. This produces joints that are often stronger than the materials themselves.
- Vibration Resistant - Riveted joints better withstand vibration and shock loads compared to many other mechanical fasteners. The flare distributes stress over a larger area.
- Quick Installation - Drilling holes and setting rivets can be done rapidly by hand or with automated tools for high-volume production. Minimal surface preparation is required.
- Cost Effective - Rivets themselves are inexpensive. Installation doesn't require expensive equipment. And riveting creates joints quickly, reducing labor time versus welding or bonding.
- No Heat Affected Zone - The cold mechanical process doesn't alter the microstructure of metals like welding does. There is no heat affected zone.
- Appearance - Protruding rivet heads can enhance products aesthetically and make an industrial or tech-inspired styling statement.
Common Rivet Types for Sheet Metal
Many rivet varieties are suitable for sheet metal fabrication. Some of the most popular include:
- Solid/Round Head Rivets - A basic rivet style with a domed head. Used for general applications with standard rivet setters.
- Countersunk Head Rivets - Feature a flat, tapered head that sits flush with surfaces for an inconspicuous appearance. Require specialized setting tools.
- Large Flange Rivets - Have oversized domed heads that distribute load over a wider area. Help reinforce thin sheet metals.
- Blind Rivets - Tubular with builtin mandrels. Settable from one side for securing sheet metals where only one surface is accessible.
- Self-Piercing Rivets - Pierce and set in a single operation without pre-drilling. Quickly join stacked sheets but only recommended for softer metals like aluminum.
- Structural Rivets - Engineered with higher shear and tensile strength for critical structural applications. Require pneumatic tools for setting heavy-duty rivets.
Rivet Materials
Steel, aluminum, stainless steel, copper, and Monel are common rivet materials. They are matched to the metals being joined to prevent galvanic corrosion. Using the same alloy is ideal, but the following combinations also work well:
- Aluminum rivets in aluminum, magnesium, or zinc sheets
- Stainless steel rivets in stainless, galvanized, or aluminum sheets
- Copper rivets in copper sheets
- Monel rivets in stainless steel or Monel sheets
Keep in mind that harder rivets can damage softer sheet metals during setting. Size properly and use rivet types that flare smoothly.
Rivet Strength and Hole Sizing
The relationship between rivet diameter and sheet thickness significantly impacts joint strength. Follow these general sizing guidelines:
- Rivet Diameter - At least 2 times metal thickness but up to 4 times for optimal performance
- Hole Diameter - Equal to rivet diameter in soft metals, 0.1 mm larger in harder alloys
- Sheet Thickness - Up to 1.5 times rivet length between sheets for best results
Proper hole spacing is also critical. Allow at least 4 diameters center-to-center between rivets in the same row. Space rows 2-3 diameters apart. Avoid placing holes too close to sheet edges.
Use annular ring or domed head rivets with smaller flange diameters in thin sheets to prevent tearing around holes. Blind rivets are also ideal for securing thin metal sheets.
Riveting Process
These are the basic steps for manual riveting in sheet metal fabrication:
1. Prepare materials - Deburr holes and clean surfaces of dirt, oil, and other contaminants.
2. Insert rivets - Place rivets through aligned holes with mandrel stems protruding on the backside.
3. Position materials - Clamp or hold sheets together firmly so holes line up accurately.
4. Set rivets - Use a rivet gun, hammer, or rivet squeezer to flare out the rivet body, clamping materials together.
5. Remove mandrels - Cut or snap off unwanted mandrel stems.
6. Inspect joints - Check for proper rivet flaring and clamping. Re-drive any loose rivets.
For production shops, pneumatic and hydraulic squeezers offer faster, more consistent rivet setting. Auto-fed tools are also available to improve efficiency and reduce worker fatigue on high-volume jobs.
Riveted joints may still allow slight slip between materials. Use close rivet spacing or interference-fit holes to increase rigidity if needed. Adhesives can also help strengthen the bond.
Riveted Sheet Metal Joint Applications
Riveting excels at assembling sheet metal parts made from alloys and gauges commonly used in:
- Aircraft and Aerospace Vehicles - Rivets securely fasten aluminum fuselage skins and other components where low weight and high strength are critical.
- Building Exteriors - Copper, galvanized steel, and aluminum sheets are riveted into decorative facades and architectural cladding.
- Electronics Enclosure and Chassis - Rivets neatly join thin aluminum or steel panels into electronics housings.
- HVAC Ducting - Stainless steel and galvanized steel duct segments are riveted for durable airflow conveyance.
- Machinery Housings and Guards - Riveted metal shrouds protect equipment without adding unnecessary weight.
- Transportation Vehicles - Rivets provide lightweight durability for vessel hulls, truck cabs, rail cars, and automobile bodies.
- Furniture and Displays - Steel and aluminum sheets get riveted into industrial and commercial furniture frames.
Almost any application where precise alignment, vibration resistance, and strong sheet metal bonds are valued can benefit from riveting. Proper joint design, hole sizing, and rivet selection results in optimal performance. With the right techniques, rivets produce rugged yet attractive sheet metal fabrications. CNC Milling