Riveting
Rivet selection and hole preparation; edge distance and pitch; countersinking and dimpling; driving and formed-head dimensions; joint inspection and rivet removal.
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
1. A solid rivet is to join sheets of total thickness 3.2 mm. Allowing one and a half diameters for the formed head on a 4 mm rivet, the rivet length required is:
9.2 mm4.8 mm12.8 mm2. A row of rivets is spaced at a pitch of 24 mm over a run of 240 mm, with a rivet at each end. The number of rivets is:
1110123. On the riveted joint shown, the dimension marked E is the edge distance for 4 mm rivets. Its usual minimum is:
8 mm, two rivet diameters4 mm, one rivet diameter16 mm, four rivet diameters4. Minimum rivet edge distance is normally:
2D1D4D5. Rivet pitch is normally kept within:
3D-10D1D-2D10D-20D6. Flush riveting of thin sheet is achieved by:
DimplingMachine countersinkingChamfering the rivet7. The formed (shop) head should be approximately:
1.5D diameter and 0.5D high1D diameter and 1D high2D diameter and 2D high8. A 4 mm rivet requires a minimum edge distance of:
8 mm4 mm12 mm9. 'Smoking' around a rivet head indicates:
The rivet is loose and fretting in its holeCorrect installationHeat treatment in progress10. A drilled rivet hole must be:
DeburredLeft as drilledCountersunk in all cases11. Ice-box rivets are refrigerated in order to:
Delay age-hardening so they stay soft enough to driveMake them harder before driving, so that the formed head resists deformation in servicePrevent corrosion of the alloy while the rivets are held in stores before use12. A defective rivet is removed by:
Drilling the head and punching out the shankDrilling straight through the shankLevering the head off