Riveting in Sheet Metal Fabrication(how to plastic weld Jodie)

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Riveting is a crucial process in sheet metal fabrication that involves joining two or more pieces of metal together using a rivet. Though welding and screwing are more common nowadays, riveting still has its applications in aircraft, automobiles, appliances, furniture and many other products.
What is a Rivet?
A rivet is a mechanical fastener that consists of two main parts - the body and the mandrel. The body is a cylindrical shaft with a head on one end. The mandrel stems from the opposite end of the body and keeps the rivet rigid.
To join materials, the rivet body is inserted into pre-drilled holes in the materials being fastened. The excess portion of the mandrel is then removed using a riveting hammer, upsetting the rivet and causing the body to flare out and clamp the materials together. The flared portion is called the shop head or buck-tail.
Benefits of Riveting:
- Riveting creates a highly reliable, permanent and vibration resistant joint. The shop head actually gets stronger over time.
- It can join dissimilar metals or multiple sheets of material.
- Minimal surface preparation is required compared to welding.
- The process induces less distortion than welding thin sheets.
- Riveted joints have some flexibility to absorb forces if the materials expand or contract.
- Installation is quick and often automated in modern manufacturing. Replacement of just a few rivets can repair a joint.
- It produces a aesthetically pleasing seam that requires no finishing work.
- The riveting process is cleaner than many alternatives, producing no fumes or arcs.
Types of Rivets:
- Solid/One-piece rivets are the simplest type, made entirely from the rivet body material. They are ideal for softer materials like aluminum.
- Blind rivets have the mandrel separate from the body so it can be expelled after installation. This allows riveting when access is only available from one side.
- Drive rivets have pre-formed heads so no flaring tool is required. They are simply driven into place and often used for temporary fastening.
- Split rivets have the mandrel attached to the head. As it's drawn into the rivet, it splits the body and flares the legs outward.
- Tubular rivets are a form of blind rivet where the buck-tail forms the rivet head. The mandrel snaps off after installation.
Riveting Process:
The main steps involved in riveting sheet metal are:
1. Drilling matching holes in the materials to be joined. They should be centered and perpendicular with no space between the sheets.
2. Selecting the proper rivet type and size to fit the materials and application. The rivet body diameter should match the hole closely.
3. Inserting the rivet into the holes with the manufactured head against one material.
4. Positioning the bucktail die of a rivet gun against the rivet body. The die shapes the unset end during hammering.
5. Activating the rivet hammer to upset the tail and flare the body, clamping the materials together.
6. Removing any remaining mandrel portion if blind or split rivets were used.
7. Inspecting the shop head for proper formation and tightness. Re-striking may be necessary if loose.
Riveting Tools:
- Rivet guns use air pressure or hydraulic force to quickly upset rivets. They allow one-handed operation and are essential for mass production.
- Hand squeezers are hinged tools that manually compress blind rivets to set them. Used where rivet guns can't access.
- Hand rivet sets are hammered directly to upset rivets. Available with various die shapes to suit different rivet types and materials.
- Drill presses with standard twist bits are commonly used to drill rivet holes. Fixtures help locate holes precisely.
- Hole punch tools can punch holes instead of drilling for quick hole alignment. Often used for soft materials like aluminum.
- Countersink tools chamfer hole edges to recess rivet heads. Required for flush finishing in some applications.
Riveted Joint Design:
Proper design is key to creating strong, long-lasting riveted connections:
- Spacing between rivets should be 2-4 times the rivet diameter. Closer spacing reduces joint flexibility.
- Edge distance from rivet holes to the sheet edge should exceed 1.5 times the hole diameter. This prevents edge tearing.
- Lap joints should overlap sheet edges by at least 3 times the material thickness. More overlap is needed for softer or thinner materials.
- Rows of multiple rivets should be staggered for best load distribution. Aligning rows weakens the joint.
- Materials over 1/8 inch thick may require countersunk rivets so heads sit flush. This smooths airflow in aircraft or wind force applications.
- Rivets with large grip ranges should be selected when joining varying material stacks. Consistent clamping requires the right grip.
- Structural joints may need special heavy duty rivets to meet tension and shear strength requirements.
Inspecting Riveted Joints:
Once installed, rivets should be visually and physically inspected to verify proper function:
- Rivet heads and shop heads should be formed symmetrically without cracks or extrusion fins.
- Shop heads should seat fully against materials with minimal gap. Loose rivets must be replaced.
- No scratches, gouges or discoloration should surround holes from riveting damage.
- A light hammer tap should produce a uniform ringing tone across each rivet, not a dull thud.
- Random pull tests on sample rivets can evaluate gripping strength. Loose samples indicate flawed installation.
Though one of the oldest metal joining methods, riveting remains a common process in fabrication of aircraft, appliances, machinery, bridges and countless other products. Correct joint design, hole drilling, rivet selection and installation practice results in durable, trustworthy riveted bonds. With attention to detail, it will continue enabling metalwork for decades to come. CNC Milling CNC Machining