1. Winding tests on Roebel cables
Maria Durante
In behalf of task 3 members

2. Non insulated Roebel cables
At Saclay, 15 x 150 µm thick strands, 226 mm twist pitch
Manually wound
At CERN, 15 x 100 µm thick strands, 226 mm twist pitch
Winding machine
Hand tension *

3. Insulated Roebel cable
Roebel cable insulated with mm thick E-glass fibers sleeve
At Saclay, 10 mm wide cable
15 x 150 µm, 226 mm, assembled at CEA
15 x 100 µm, 426 mm, from KIT
Winding machine
Max tension on cable 10 daN

4. Insulated Roebel cable
Roebel cable insulated with mm thick E-glass fibers sleeve
At CERN, 12 mm wide cable
Winding machine
Hand tension
Feather Zero 1st coil
Feather 2 , two layer

5. Winding tension 15 kg damage a single tape.(Jaakko)
At CERN tension less than 5 kg per tape
At CEA tension of 10 kg on cable

6. Cable unravelling
This happens at the ends and occasionally in the straight section..
It would be nice to find a way of fixing the cable to stop it from coming apart :
tape , clips, Teflon tape….

7. Cable geometry modification
Uneven distribution of the strands in the cable.
Meander tapes were evenly distributed during cable manufacturing
Tapes have slipped during transfert onto transport mandrel
We did not manage to re-configure the cable without complete disassembling it (length > 10 m).
Solution: Spool as big as possible?
12 mm wide cable , tp 226 mm, winding at CERN
10 mm wide cable , tp 426 mm, reception at CEA

8. Cable geometry modification
Vertical gap closing
10 mm wide cable , tp 226 mm at CEA

9. Damage from tooling! Tooling damages dummy cable
Tooling improved but still ongoing disruption

10. Slippage during winding
about ~ 5-6 mm
Longitudinal gap = 17.4 mm (Tp = 426 mm, perfect distribution)
Longitudinal gap = 4 mm (Tp = 226 mm, perfect distribution)
Real issue if the slippage is between two successive strands!
buckling cable smoothed out till the end of the winding
->Smoothing out of the buckling cable no more possible

11. Pop up!
Pushing the cable flat makes the same strand pop-up further along the cable

12. Fiber glass damage At CERN damage of the glass fiber At CEA no damage
Likely due to stamping burr
At CEA no damage
10 mm wide cable in 12 mm wide insulation
Results may differ with 12 mm wide cable

13. Winding tests conclusions
Delicate cable handling: tooling, unravelling
Fragile fiberglass insulation: sharp edges, stamping burr
Cable geometry modification: strand distribution, gap closing
Cable winding on circular mandrel shuffling tape distribution
Slippage of the tapes needed: otherwise cable popping up
Undistributed winding tension due to slippage

14. Spares

15. Roebel cables delivered at Saclay
SS dummy cable punched at CERN, assembled by CEA
10 mm wide
15 x mm thick strands, twist pitch 226 mm
2 lenghts, 2 m long, right-hand lay
1 lenght, 2 m long, left-hand lay
SS dummy cable from KIT
15 x mm thick strands, twist pitch 426 mm
1 lenght, 13 m long, left-hand lay
12 mm wide
15 x 0.15 mm thick strands, twist pitch 226 mm
1 length, 20 m long, left-hand lay, just delivered (07/05/2015)

16. Expected tape slipping
If the cable is wound on a 5-cm radius spool (or bigger) before shipping the relative slippage should be negligible (less than ±0.5 mm):
Tp = 226 mm
R = 5 cm
ep cable = 1.2 mm
Nb tapes = 15
J. Fleiter, C. Lorin et al On Roebel cable geometry for accelerator magnet
CERN-ACC-NOTE