22.02.2011 Deformations of waveguide ring during brazing

• The shape of the ring does not matter, the average radius / diameter is the important quantity. The tooling for EB-welding will shape the rings adequately.
• Metrology reports of PIMS prototype: https://edms.cern.ch/document/1059389/1

22.02.2011 Temperature influence on metrology measurements

• Linear expansion coefficient of copper at 20 degrees: a ~ 16.6*10^-6 / K. A diameter of 540 mm changes by ~ 9 um for a temperature increase of 1 degree. Our specification of temperature during measurement of 20 degrees +- 1 degree is at / over the limit for required tolerance of +- 10 um. Additionally, the precision of the metrology measurements is in the same order (prototype 6 um).

10.03.2011 Deformations of rings during machining

• Machining of ring for tests: Problem of ellipticity. Internal stresses in the material or stresses induced by the fixation / jwas are likely to cause deformations which are seem in deviations form perfect circular shape. With improvements on machining and clamping, the deviation could be reduced from 2.2 mm to 0.5 mm. However, the tightest tolerance specified is 10 um!
• Metrology reports of PIMS prototype show that there was a similar problem at CERN, even after stabilisation and fine machining: https://edms.cern.ch/document/1064105/1, https://edms.cern.ch/document/1064183/1, https://edms.cern.ch/document/1064175/1, https://edms.cern.ch/document/1064169/1.
• Important is the average diameter, the ellipticity can be compensated to certain extent by external forces during assembly. However, discs and cylinders need to be assembled and disassembled several times and therefore the ellipticity can not be in the order of millimeter. => Suggestion to change specifications from profile tolerance to tolerance of average diameter and max ellipticity. To be discussed.
• Suggestion of Marc: Maurice, a very experienced tuner can join us for 2 days to Poland to work there directly on the fixation.

-- RolfWegner - 10-Mar-2011