Analysis and Treatment of Common Problems in Ultrasonic Riveting
1. The rivet head is inconsistent and the appearance is uneven
Reason:
- The riveting cavity is too large or the pin is too short
- Excessive amplitude leads to material degradation
Solution:
- Reduce the size of the cavity or increase the height of the pin
- Reduce the amplitude or use the amplitude step
2. There are too many flash edges around the rivet head
Reason:
- The riveting cavity is too small or the pin is too high
- Mechanical stop setting is too high
- The pin is not centered in the cavity of the welding head
Solution:
- Increase the size of the cavity or reduce the height of the pin
- Reduce mechanical stops
- Check concentricity
3. The rivet is formed at the upper pin of the pin; the bottom of the pin melts and begins to shrink
Reason:
- The sharp corner at the bottom of the pin causes stress concentration
- The clamping pressure is too high or the amplitude is too small
- The welding head is too short or the speed is too fast.
Solution:
- Increase the radius at the bottom of the pin
- Reduce the pressure too high or increase the amplitude
- Increase the downstroke or decrease the descending speed
4. Severe indentation and deformation on the other side of the rivet head
Reason:
- Improper clamping
- The clamping pressure is too large
Solution:
- Test the metal support fixture and reduce the amplitude in the lower part of the riveting area
- Reduce the clamping pressure and place a metal plate between the pin and the clamp as a heat sink to reduce the indentation
5. Loose workpiece after riveting
Reason:
- The molten pin does not completely solidify before the pressure is released.
- Limit stop or lower limit setting is too high
Solution:
- Extend the pressure holding time
- Reduce mechanical stops
6. The bottom of the pin is broken during the riveting process
Reason:
- Stress concentration at the sharp corner of the pin
- The pin and the tip of the horn are not perpendicular
Solution:
- Increase the bottom radius of the pin
- Check the alignment
7. Deformation caused by plastic flow between workpieces during riveting
Reason:
- The amplitude is too high
- The gap between the pin and the hole is too large
Solution:
- Reduce amplitude or purchase amplitude step
- Reduce the aperture
- Use an external or external node plunger for better sealing
8. Severe indentation and deformation on the other side of the rivet head
Reason:
The metal is not properly placed at the bottom of the plastic part
Solution:
- Increase welding and holding time
- Increase the height of the pin
9. The rivet head is poorly formed and the pin material sticks to the surface of the horn
Reason:
- Poor fit between the pin diameter and the through hole
- Material flows into the gap between the pin and the workpiece
- Insufficient lubrication of the surface of the welding head
Solution:
- Slip fit between the pin and the through hole
- Improve the fit between the pin and the through hole
- Test weld head coating (such as TiN)
