________________________________

From: Erik D. Perry 
Sent: Wednesday, October 25, 2006 8:50 AM
To: Wayne T. Reiersen; 'dtanders@facstaff.wisc.edu'; 'Lutz Wegener (lutz.wegener@ipp.mpg.de)'; 'knowlton@physics.auburn.edu'; ' Tom McManamy (mcmanamytj@ornl.gov)'; 'Torsten Braeuer (torsten.braeuer@ipp.mpg.de)'; Erik D. Perry; Geoffrey J. Gettelfinger; 'Simon Anderson'; 'Ken Chipley (ChipleyKK@ornl.gov)'; James H. Chrzanowski
Cc: Hutch Neilson; Mike Williams; Lawrence E. Dudek; Phil Heitzenroeder; Arthur W. Brooks; 'Mike Cole'; Thomas G. Brown; Michael E. Viola
Subject: NCSX Field Period Assembly Review Summary

 

      Attached is the spreadsheet of chits which were generated during the NCSX Field Period Assembly Peer Review on October 11th and 12th.  Please let me know if I missed anything or if something is not stated properly.  

 

      At the close of the review, the participants went through the six questions posed as the review objective.  The collective response was as follows:

 

1.  Does our technical approach to field period assembly appear feasible?

      

All participants stated that they felt the approach is feasible.

 

2.        Are metrology provisions and tooling design suitable?

 

The consensus is that another Leica Laser Tracker should be obtained (rented?) and the Project should contact the survey and alignment group at SRS to find out about any lessons learned they might have.  Another Laser Tracker operator will also be required.

 

3.        Are dimensional control requirements realizable?

 

The feeling of those who have done this sort of assembly before is that the statements about the accuracy of the Laser Tracker are overly optimistic.  The Project should spend a lot of time in preparation for alignments (planning out how to do the measurements in a way that will maximize accuracy), but then expect only accuracies of 0.1MM when multiple set-ups of the Laser Tracker are needed.

 

W-7X is using the same procedure for measuring current center and then adjusting single coils, then all of them together, and finally measure what has been actually achieved.

 

 

4.        Are time and resource allocations reasonable?

 

The caution here was to not be too optimistic because the number of units is small.  For example, for the coil winding effort the learning curve did not really start until after the first three coils.  Then there was a diluting of the experienced technicians as the team size was increased.  The estimate of what was needed to do the first item turned out to be very light.

 

It was noted that a machining error will lead to a lot more metrology effort.

 

The consensus was that a contingency of at least 30% would be needed for the first Field Period Assembly.

 

5.        What are the most significant risks?

 

The participants identified the following areas as having significant risks:

 

a. Metrology (need more resources)

       b. Back-ups for key technicians

       c. Get prompt feedback from suppliers when they have a problem

       d. Limits of metrology

       e. WBS shows amount of time to complete stations 3, 4, & 5 is quite tight

       f. Not leak-checking until final assembly

       g. Detail design for shimming not finalized – looks like dual load paths 

       h. When you are removing the spherical seats will you lose the alignment

       i. Large down time during the manufacturing of the shims – especially 3D ones

              (W-7 sees a two week down time to get a shim made)

       j. Shim design still needs R&D, especially if liquid shim is considered

 

6.        What might we do differently?

 

This was addressed as part of question #5.

 

 

 

The day after the Review, Lutz Wegener sent the following summary comments:

 

a. In the opinion of W7-X the approach presented for the FPA is feasible.

 

b. The metrology provision is suitable but the resource should be increased, i.e. second laser tracker and review of other suitable equipment.

 

c. The tooling design appears to be suitable. The rigidity for stands 2 thru 5 (10/1000 inch accuracy) must be considered in the detailed design and checked. The stiffness effects the speed of work and the accuracy of the results.

 

d. Dimensional control: PPPL is working at or beyond the reliable limits of metrology systems. The planned mushroom system has to be checked whether it works save within the planned accuracies particularly the plan used in stage 3 (vertical use).

e. The schedule appears to be very tight; particular procurement of stage 3 thru 5 tooling. In the discussion we got the impression that sufficiently trained staff would be available when required, i.e. will be transferred from coil production.

 

f. Risks: overoptimistic schedules of tooling supplies; planned accuracy and the time required to achieve it 

 

g. What might be done differently:

 

i. Station 3: we would not rely on the crane for final adjustment and accuracy (better with mechanical systems from underneath)

 

ii. Qualification and development of tooling: define and allocate sufficient engineers capacity to ensure that all packages are worked in parallel

 

iii. Try to identify early (in advance) “small” tooling fixtures to avoid surprises

 

 

In general it was felt that the Field Period Assembly Plan is going in the right direction, but there are a number of issues which need to be addressed promptly and in a practical manner.  Solutions should be derived from what can be done by the field crews and further studies or elaborate fixturing should be avoided.

 

                  Erik