Riveting
Familiarisation with solid-rivet joints, how the joint is formed, the basic layout rules and what a defective rivet looks like.
Riveting, summary notes
- A solid-rivet joint depends on correct rivet selection, hole preparation, layout and driving.
- The rivet material and diameter are chosen for the load and the sheet thickness. Some aluminium alloy rivets (2024, 'ice-box' rivets) are heat-treated and stored refrigerated to delay age-hardening, and must be driven within their specified time out of the freezer.
- The hole is drilled to give a slight clearance on the rivet shank and is deburred, since a burr holds the sheets apart and starts a crack.
- Layout: edge distance is not less than 2D (D = rivet diameter) so the joint cannot tear out at the edge, and pitch lies between 3D and 10D, too close weakens the sheet, too far lets the joint gape between rivets.
- For flush joints the sheet is COUNTERSUNK when thick enough to take the head, and DIMPLED when too thin, countersinking thin sheet would cut through it and leave a knife edge.
- The driven (shop) head is formed to about 1.5D diameter and 0.5D height. Under-driving leaves it loose; over-driving cracks the head or distorts the sheet.
- Inspection: correct rivet type, fully driven, heads concentric and to size, no cracked, tipped, loose or 'smoking' heads, no cracked or distorted sheet, and correct flushness on countersunk work. Loose rivets are found by tapping and by a dark fretting ring around the head.
- Removal: drill the head centrally to its depth and punch out the shank, never drill through the shank, which enlarges and damages the hole.
- ⚠ Exam trap: 2D edge distance is a MINIMUM, not a target, and thin sheet is dimpled, never countersunk.
- Edge distance
- ≥ 2D (D = rivet diameter)
- Pitch
- 3D - 10D
- Formed head
- ≈ 1.5D diameter × 0.5D height
- Flush method
- thick sheet → countersink · thin sheet → dimple
A repair uses 4 mm rivets. State the minimum edge distance and the acceptable pitch range.
Minimum edge distance is 2D = 8 mm. Pitch runs from 3D = 12 mm to 10D = 40 mm; the designer's figure within that band is what the repair scheme specifies.
Why is 'smoking' around a rivet head a rejection?
The dark smudge is fretting debris from the rivet working in its hole under load. It shows the rivet is loose and no longer carrying its share, so the joint is progressively transferring load to its neighbours and must be repaired.
Riveting concept map
Riveting
Riveting quiz
Riveting, quiz (Level 1)
1. Minimum rivet edge distance is normally:
2D1D5D2. A solid rivet forms its joint by:
Being upset to form a second headScrewing into the sheetBonding chemically3. Thin sheet is prepared for flush riveting by:
DimplingCountersinkingGrinding4. A loose rivet may be identified by:
A dark ring around the headA shiny headA painted head5. Rivet holes are deburred because a burr:
Holds the sheets apart and starts a crackImproves gripHelps the rivet enter6. A defective rivet is removed by:
Drilling the head and punching the shank outDrilling through the shankChiselling the sheet