1. Galling 4 3 2 1 baseline 3) Reference K. Artoos
Solution
Advantages
Disadvantages
Comments
Silver / copper coating
Solid
Not easy to do (neither at CERN neither outside) – very thin coating (3 um)
PVD deposition could be an alternative
IBE surface treatment
457€ per set (≈2-5 € /bolt)
Never tested. Should be suitable for UHV
Dicronite dry lubricant
“anti-galling” declared, used in SPL3) and XFEL3) ?
Never used at CERN
Molykote® 321
Dry Film Lubricant Spray
Cheap, used in UHV devices for nuclear plan1)
Cryolab2), already used in tiny amount
Solvent dispersion of MoS2,
graphite and inorganic binder / Used in Linac 4 (at warm)
Vacuum grease (Apiezon N)
Used in all the cryostat devices (vacuum sealing, thermal coupling…)
Used in collimators, radiation resistant
Used for sealing. To be tested
Silicone oil + Inorganic thickener 4 3 2 1
baseline
3) Reference K. Artoos
1) Reference A. Lafuente Mazuecos
2) Reference T. Koettig

2. Locking baseline 1 3 2 1) Reference A. Lafuente Mazuecos Solution Adv
Disadv
Comments
Serrated Belleville Washer in CuSn8
NASA References: looking effect
Stiffness value unknown
They combine spring effect + locking effect
Standard Belleville washers in Ti with additional “machining”
High cost
Ask for quotation
Positive locking device (mechanical )
i.e. lock wire or tab washer
Highly reliable
Complex
Could be too complicate to add
Thread -> Spiralock (friction locking device)
Good reference: used in nuclear plan1) , used in space, already used in Ti4Al6V, suggested by NASA reference
Test needed
The only reference is the
Not reliable with vibrations
Cost for the tool (90 € per tool) 1 3 2
1) Reference A. Lafuente Mazuecos

3. Washers (1) Why? Do we really need a washer? Role of a washer:
Locking effect
Bearing surface function (Pressure under the screw)
Spacer function
Spring function (Preload regularization)
Belleville or Grower have the same function if they are not flattened
New offer for Grower washers:
1.52 € per washer (total for tests and dummy: 485 €)
Warning: washers need to be fully compressed if we want that the FE models are reliable!!!

4. Schnorr: CuSn 8 (2.1030) - Tin bronze according to DIN EN 1654
Washers (2)
Schnorr: CuSn 8 (2.1030) - Tin bronze according to DIN EN 1654
Integrated thermal contraction (293K-4K): I assume pure Cu -> 0.324% (for pure Ti -> 0.151%)
Assuming 1 mm thickness: (0.324%-0.151%)*1mm= 1.7 um
Missed information: spring stiffness?

5. Ti Grade 6 bolts We have offer for pre-series. M6 12.25 € per bolt
delivery time: 4.25 months