Minutes of the Tracker Meeting

June 5, 2002

 

Action Items:

  1. Luisella: send the tungsten assembly tool drawing to BJ by end of next week.
  2. Tom: take unused trays to Italy.
  3. BJ: take the top/bottom tray assembly fixture drawings to the shop.

 

Luisella said that BJ can call her at 39050880413 for discussions of the drawings.

 

The assembly tool drawing for top/bottom trays looks okay to Luisella, except that it needs an orthogonality tolerance between closeout walls. She used a value 0.05mm maximum deviation over the tray length.

 

Tom reported on the vibration experiment at Ames on Monday and Tuesday. The z-axis test was fully successfully with 2 minutes at 6dB (launch levels), 2 min 3dB (acceptance levels), and 2 min at 0dB (qualification levels from GEVS of 12.3 g rms). After that they verified the torque on the flexures and proceeded to the x-axis. In x axis vibration some screws in the sidewalls lost a small amount of torque. After the 0dB test they checked torque on the flexures again and found the bolts loose into the tray on all 4 corners. The midspan flexures were still perfect. They tried to retorque the 4 corners and half of the screws would not torque; the inserts were loose. Tom noted that the flange on the end of the insert is only slightly larger than the hole, so when torqueing the screws the stress is mostly going onto the bondline of the insert barrel. He would like that flange to be increased and also would like steel inserts in the bottom tray, to allow greater torque. As a result of the insert failure, the fundamental frequency went from 80 Hz down to 50 Hz by the end of the test. He suggested using the top tray with some modifications for a new test, but first some analysis has to be done.

 

Luisella said that on Friday they QCed the 1st 9 closeouts, with results on their web site. They look acceptable, for both Plyform & GMSI parts. Tom will post it on the SLAC web site also (see: http://www-glast.slac.stanford.edu/Tracker-Hardware/docs/other_docs.html). Yesterday Plyform finished more closeouts (32 pieces total). GMSI machined 20 pieces of each type. Luisella et al. will go to Plyform again this Friday to discuss procedures for bonding inserts. Monday should see the start of bonding of inserts.

 

The tray assembly tool also is in good shape, for regular and heavy mid trays. Today they are beginning to make face sheets and will begin tray assembly a week from Monday.

 

Friday Luisella will take a sketch of the Tungsten assembly tool drawing to Plyform for review. She will send drawings to BJ at the end of next week. The Pisa group will check on an ultrasound system for panel QC next week.

 

Sandro needs the regular PCI tray with heavy tungsten and the regular tray made by Plyform for tests on bonding quality and thermal tests. Tom will take the unused trays with him to Italy.

 

BJ will take the top/bottom tray panel assembly fixture to the machine shop today. He is starting this week on the insert bonding tool drawing for top/bottom trays.

 

Tom still needs to call Teledyne. The 1mm screws arrive this Friday. He needs to chase down the cups for encapsulation.

 

Tom said that the thermal gasket material is still not as resilient as we would like. Tom will look for another material, perhaps sacrificing a bit on the thermal conductivity to get better mechanical performance.

 

The module lifting/handling fixture design is not started yet.

 

SLAC purchasing on the verge of placing a order for the readout flex cables. The same is true for closeout wall material for the flight build.