Comments from reviewers and updated

hardtofindcurtainUrban and Civil

Nov 16, 2013 (3 years and 6 months ago)

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Comments from reviewers and updated
plans


G. Ambrosio and P. Ferracin

October, 21 2013


General comments/requests


SC


My
opinion regarding end
-
parts criteria is that if the conductor looks good the spacers are good
enough.


Having said that we should ensure that:


The
first turn wraps around a spacer without a gap


No
gap between the last turn and the following spacer


Following
impregnation use an internal inspection to ensure turns linearity, no or little S curves
.


FN


With coil winding at CERN and LARP, what is the selection criteria for a particular design
considering all the various parameters like cable tension, cable type (Cu, Nb
3
Sn), cable insulation
(tape, sleeve), end part configuration (slits, no slits, flex legs) etc.? No evaluation criteria was
presented
.


PF


Establish a check list for the selection and evaluation criteria on


Establish common procedures from the beginning. Make clear to the technicians that they are
not alone but another guy on the other side of the ocean is doing the same thing of him and the
results shall be the same. If during agreed test it looks like a different option/solution

is better,
before you complete the assigned test and then you do the other one in addition. This will allow
everyone to move forward together.




21/10/2013

G. Ambrosio and P. Ferracin

2

Different codes


BA


Starting
on two alternative designs is useful if there is an uncertainty as to which design criteria are more
important. The direct comparison brings clarity.

In the MQXF project there is no such difference in criteria.
Therefore, there is no clear necessity to pursue multiple options. Recommend to go with one design quickly
through the necessary iterations that will yield a good enough end design.



Which tool is used is secondary. Susana showed conclusively that both, ROXIE and BEND, can yield identical
designs with standard input parameters. That Susana's version is more pointed has to do with the fact that she
did not use the order of the hyper
-
ellipse as a free parameter.


If BEND is used, either the interface to ROXIE should be revived, or the ends are reproduced with ROXIE. Both
options are practicable. The first is beneficial also for other projects. The latter does not seem too time
consuming either.



FN


There
is a lot of effort to manipulate Roxie output to look like the BEND end part design, like the winding key.
Most of it is straight forward, but not the torsion parameters TORS1
-
TORS4. These parameters are used to
insure that the surface vectors


are at least close to the rulings of the BEND design. As a result, I recommend
using BEND as the primary tool for end part design. Investigate the program written by GianLuca to input BEND
files into Roxie for magnetic analysis and end part design evaluation.


SC


Be reasonable with whatever computer program is used, it is based on a mathematical concept (zero strain) and
does not take into account material properties (e.g. no stress analysis). Personally I would use BEND
.


PF


Use the program that you like the most, avoid calling one the BEND design and the other the ROXIE design. The
key is the person using the tool, her/his understanding of the problem, what she/he wants to do. For me they
are equivalent.

Results matter. Nevertheless (see below)


When a design has been agreed the source file for the production and the drawings shall come only from one
place and they should be stored on a common web site





21/10/2013

G. Ambrosio and P. Ferracin

3

Rapid prototype parts


BA


Where
iteration is needed to close gaps, in the past we made good experience with central
-
post
-
type fast
-
prototyping pieces like those in the attached image that can easily be produced for any block. Test
-
winding
without insulation gave good insight in the actual dynamics of the cable
.


FN


In general, make 3D printed parts with various final edge angles (nose angle) and do single turn winding tests of
problematic current blocks.


It
was mentioned that end parts were not inspected prior to coil winding. Recommend using QC inspected end
parts prior to coil winding
.


As was recommended recently in the 11 Tesla Dipole Readiness Review, do the necessary analysis and
mechanical testing of laser sintered parts as part of the qualification process for the material


and the laser
sinter process. This could be shared/coordinated effort between the 2 projects
.


SC


Use rapid prototype parts as a variable. For a given choice of A
-
length and angle, vary the angle by +
-

3
-
5
degrees and try several such parts during winding. The techs should be able and provide useful feedback.


Fix
each part as you become aware of it, we cannot afford the time or justify the performance by trying to
reduce problems one at the time
.


PF


Complete qualification of the metallic rapid proto material but define before the criteria and do not make them
unnecessarily
demanding


In order to have stable winding condition for a series of coils differences in +/
-

0.1

0.15 mm on the curve part of
the spacer in contact of the cable shall not affect the final results. On the other hand material thickness in
prolongation to the wedges shall be in +/
-
0.01 0.02 range. This dimension can be easily measured by hand and
will provide indication of the quality of the pieces.


Personally I would do 3D checking to understand the
production capability of the rapid proto, but in series this shall be a statistical check







21/10/2013

G. Ambrosio and P. Ferracin

4

Short/long legs


BA


It is reasonable to aim for short spacer "legs". A criterion is needed to
define where spacers can be cut
.


FN


Recommend always making end part spacer legs that transition to a
wedge to be as short as possible
.


SC


The straight
-
section wedges should be staggered as they are terminated,
e.g. the wedge length near the pole should be shorter than the one close
to the mid
-
plane. Avoid including a wedge
-
like straight section in the
spacer.


PF


Stagger
the transition wedge

end
spacer


Straight part could be included in the spacer wedge during the design
and initial proto phase. Then preparing the drawings for real coil, shift
them to the straight part wedges. This will also reduce costs





21/10/2013

G. Ambrosio and P. Ferracin

5

BEND/ROXIE parameters


BA


The final integrated field
-
quality optimization should be done once the
applicable cable parameters (FAT and KEY in BEND, virtual
-
wedge dimensions in
ROXIE) are known from winding tests. Note that variable parameters per block
might give better results than a single setting for the entire end.



Problems in winding can usually be correlated to specific features in the
distributions of geodesic curvature (hard
-
way bend), normal curvature (easy
-
way
bend), and torsion. This offers an efficient and insightful way to improve a
design. (For example, MQXC blocks that exhibited gaps had a maximum normal
curvature away from the apex; 11
-
T blocks that gave cable stability problems had
elevated overall torsion
.)


SC


The experience with BEND has been to reduce the “nose” angle even if strain
appears. Reduce that angle but stay above the point where errors or cable
reversal appears. Vary the A
-
length (or shift or blunt) to try and not go much
above 15 degrees.


The
FAT and KEY variables are empirical. I have used them to “cover up”
uncertainties especially when a new cable is used for the first time.



21/10/2013

G. Ambrosio and P. Ferracin

6

Flexible spacers


BA


As for accordion slits in the selective laser
-
sintering process, we have made the experience that
slits in conjunction with thermal stresses inherent to the process can lead to distorted
geometries. Careful quality control is needed
.


FN


Using end parts that don’t need to filed or modified during coil winding is a must for coil mass
production. Recommend testing the effectiveness of the

flexibilize
/accordion style end part
design in a magnet as soon as possible.


Investigate
the use of a
flexibilize

end saddle as tooling for coil winding to help protect cable
insulation and replace after curing with a monolithic end saddle.


SC


Flexing end
-
parts will make the winding process easier but may have a negative impact on the
magnet performance exactly because they are flexible.


As suggested they could be used during
winding and later replaced after curing. Their use in the magnet itself should remain an R&D
item.


PF


Piece shall not be modified in production. This is for time effectiveness, reproducibility but also
avoiding risks of electrical defects. Flexible part could be a tool, but here I have some concern on
the possibility that they could harm the electrical insulation to be checked.


Investigate the use of a flexible end saddle as tooling for coil winding to help protect cable
insulation and replace after curing with a monolithic end saddle.


Flexible end part shall be tested in HQ or LHQ before use


21/10/2013

G. Ambrosio and P. Ferracin

7

Measurements of turn positions


BA


The z
-
position and angle of each turn should be measured. No
large changes are expected after curing
.


FN


Recommend measuring each turn angle and longitudinal position
during coil winding
.


PF


Establish a unique way to control and measure turn by turn cable
position and angle. This shall be analyzed to see what is
happening and feedback in next generation. If reasonably well
done is powerful. In addition here we are facing what it will be a
multi
-
site production chain. Having comparable quantities
to

match is key to understand what is happening on each
production site and understand if agreed changes produce the
same effect on the product. It is the start of a common QA and QC
plan


21/10/2013

G. Ambrosio and P. Ferracin

8

Winding tension


FN


Recommend back winding test coil and repeating winding test with 25 Kg
winding tension. Measure each turn angle and longitudinal position.
Consider making another 3D printed LE part(s) with a steeper angle and
wind a single turn to evaluate how the cable responds (Block 1.b, see
page 10 of Miao’s talk).


SC


To be consistent maintain a cable tension that minimizes strands
popping. In my experience it will have a small affect on the shape of the
spacers.


PF


If it would be possible back wind the coil and rewind with 25 kg, change
the angle more vertical has probably to be done immediately.
Nevertheless take care not to change too many parameters at the same
time or the picture will get foggy (I would change only one per time). Use
the time effectiveness

of rapid proto to do this. Some years ago we
could not do it, now you can. In key position multiply the rapid proto
pieces to test different options


21/10/2013

G. Ambrosio and P. Ferracin

9

Block positioning


BA


In the final FQ iteration, avoid to have blocks in first and
second layers terminate at the same z
-
position
.


SC


Place the last turn next to the shoe of layer 2 on top of
the inner layer shoe. Avoid the last turns of both layers
from overlapping
.


PF


If possible avoid superposition of the end(or beginning)
of the last outer layer block and the last inner layer
block. But do not look only to the section. Look at the
developed heads to see if they cross/ align somewhere
else





21/10/2013

G. Ambrosio and P. Ferracin

10

Updated status and possible plan

1.
28/10
-
01/11, fabricate
short plastic
poles (BEND poles),
1
set

2.
28/10
-
01/11,
Wind/cure outer layer short Cu coil

3.
28/10
-
01/11,
Update
BEND inner/outer layer spacers after short winding test

4.
04
-
08/11
,
Update
ROXIE
inner/outer
layer
spacers

5.
11
-
15/11 fabrication inner/outer
layer
BEND
plastic spacers
(v3)
2 sets

6.
18
-
22/11
fabrication inner/outer layer
ROXIE plastic
spacers (v3) 2 sets

7.
18/11
-
6/12, CERN/
LARP
to
wind 2 short coils (
ROXIE/
BEND
) with plastic parts

1.
Cu
cable fabricated by
8/11,
insulated by
22/11

8.
9
-
13/12
Update ROXIE and
BEND
models


9.
04
-
08/11
Start
price inquiry and procurement of SQXF metal poles, 3 sets

1.
LARP will procure 6 sets

10.
11
-
15/11 Launch fabrication for IL
-
OL RE metal spacers (after receiving first
3 by)

1.
Less than 10
kCHF

2.
We need to define the cuts of the flexible spacers, the tolerances, the rounding of the corners

11.
11
-
15/11 launch the price inquiry for 6 sets of metal end spacers


12.
16
-
20/12
Launch fabrication of metal spacers for 6 coils (4 practice and 2 mirror)


21/10/2013

G. Ambrosio and P. Ferracin

11

Additional slides


21/10/2013

G. Ambrosio and P. Ferracin

12

From Bernhard


Starting on two alternative designs is useful if there is an uncertainty as to which design criteria are more important.
The direct comparison brings clarity.

In the MQXF project there is no such difference in criteria. Therefore, there is no
clear necessity to pursue multiple options. Recommend to go with one design quickly through the necessary
iterations that will yield a good enough end design.



Which tool is used is secondary. Susana showed conclusively that both, ROXIE and BEND, can yield identical designs
with standard input parameters. That Susana's version is more pointed has to do with the fact that she did not use
the order of the hyper
-
ellipse as a free parameter.


If BEND is used, either the interface to ROXIE should be revived, or the ends are reproduced with ROXIE. Both options
are practicable. The first is beneficial also for other projects. The latter does not seem too time consuming either.



Where iteration is needed to close gaps, in the past we made good experience with central
-
post
-
type fast
-
prototyping
pieces like those in the attached image that can easily be produced for any block. Test
-
winding without insulation
gave good insight in the actual dynamics of the cable.


Problems in winding can usually be correlated to specific features in the distributions of geodesic curvature (hard
-
way
bend), normal curvature (easy
-
way bend), and torsion. This offers an efficient and insightful way to improve a design.
(For example, MQXC blocks that exhibited gaps had a maximum normal curvature away from the apex; 11
-
T blocks
that gave cable stability problems had elevated overall torsion.)


The final integrated field
-
quality optimization should be done once the applicable cable parameters (FAT and KEY in
BEND, virtual
-
wedge dimensions in ROXIE) are known from winding tests. Note that variable parameters per block
might give better results than a single setting for the entire end.



The z
-
position and angle of each turn should be measured. No large changes are expected after curing.


In the final FQ iteration, avoid to have blocks in first and second layers terminate at the same z
-
position.


It is reasonable to aim for short spacer "legs". A criterion is needed to define where spacers can be cut.


As for accordion slits in the selective laser
-
sintering process, we have made the experience that slits in conjunction
with thermal stresses inherent to the process can lead to distorted geometries. Careful quality control is needed.


21/10/2013

G. Ambrosio and P. Ferracin

13

From Fred


There is a lot of effort to manipulate Roxie output to look like the BEND end part design, like the winding key. Most of
it is straight forward, but not the torsion parameters TORS1
-
TORS4. These parameters are used to insure that the
surface vectors


are at least close to the rulings of the BEND design. As a result, I recommend using BEND as the
primary tool for end part design. Investigate the program written by GianLuca to input BEND files into Roxie for
magnetic analysis and end part design evaluation.


With coil winding at CERN and LARP, what is the selection criteria for a particular design considering all the various
parameters like cable tension, cable type (Cu, Nb
3
Sn), cable insulation (tape, sleeve), end part configuration (slits, no
slits, flex legs) etc.? No evaluation criteria was presented.


Recommend
measuring each turn angle and longitudinal position during coil winding.


Recommend
back winding test coil and repeating winding test with 25 Kg winding tension. Measure each turn angle
and longitudinal position. Consider making another 3D printed LE part(s) with a steeper angle and wind a single turn
to evaluate how the cable responds (Block 1.b, see page 10 of Miao’s talk).



In
general, make 3D printed parts with various final edge angles (nose angle) and do single turn winding tests of
problematic current blocks.



It
was mentioned that end parts were not inspected prior to coil winding. Recommend using QC inspected end parts
prior to coil winding.



Recommend
always making end part spacer legs that transition to a wedge to be as short as possible.



As
was recommended recently in the 11 Tesla Dipole Readiness Review, do the necessary analysis and mechanical
testing of laser sintered parts as part of the qualification process for the material


and the laser sinter process. This
could be shared/coordinated effort between the 2 projects.



Using
end parts that don’t need to filed or modified during coil winding is a must for coil mass production.
Recommend testing the effectiveness of the

flexibilize
/accordion style end part design in a magnet as soon as
possible.



Investigate
the use of a
flexibilize

end saddle as tooling for coil winding to help protect cable insulation and replace
after curing with a monolithic end saddle.


21/10/2013

G. Ambrosio and P. Ferracin

14

From
Shlomo


My opinion regarding end
-
parts criteria is that
if the conductor looks good the spacers are good enough
.


Having said that we should ensure that:


a) The first turn wraps around a spacer without a gap


b) No gap between the last turn and the following spacer


c) Following impregnation use an internal inspection to ensure turns linearity, no or little S curves.



Recommendations
:


1)


Be reasonable with whatever computer program is used, it is based on a mathematical concept (zero strain) and
does not take into account material properties (e.g. no stress analysis). Personally I would use BEND.


2)


The experience with BEND has been to reduce the “nose” angle even if strain appears. Reduce that angle but stay
above the point where errors or cable reversal appears. Vary the A
-
length (or shift or blunt) to try and not go much
above 15 degrees.


3)


The FAT and KEY variables are empirical. I have used them to “cover up” uncertainties especially when a new cable
is used for the first time.


4)


Use rapid prototype parts as a variable. For a given choice of A
-
length and angle, vary the angle by +
-

3
-
5 degrees
and try several such parts during winding. The techs should be able and provide useful feedback.


5)


Fix each part as you become aware of it, we cannot afford the time or justify the performance by trying to reduce
problems one at the time.


6)


To be consistent maintain a cable tension that minimizes strands popping. In my experience it will have a small
affect on the shape of the spacers.


7)


Place the last turn next to the shoe of layer 2 on top of the inner layer shoe. Avoid the last turns of both layers
from overlapping.


8)


Flexing end
-
parts will make the winding process easier but may have a negative impact on the magnet
performance exactly because they are flexible.


As suggested they could be used during winding and later replaced
after curing. Their use in the magnet itself should remain an R&D item.


9)


The straight
-
section wedges should be staggered as they are terminated, e.g. the wedge length near the pole
should be shorter than the one close to the mid
-
plane. Avoid including a wedge
-
like straight section in the spacer
.

21/10/2013

G. Ambrosio and P. Ferracin

15

From Paolo


Establish
a check list for the selection and evaluation criteria on


Establish common procedures from the beginning. Make clear to the technicians that they are not alone but another guy on the
oth
er side of the ocean is
doing the same thing of him and the results shall be the same. If during agreed test it looks like a different option/solutio
n

is better, before you complete
the assigned test and then you do the other one in addition. This will allow everyone to move forward together.


Establish a unique way to control and measure turn by turn cable position and angle. This shall be analyzed to see what is ha
ppe
ning and feedback in next
generation. If reasonably well done is powerful. In addition here we are facing what it will be a multi
-
site production chain. H
aving comparable quantities
to

match is key to understand what is happening on each production site and understand if agreed changes produce the same effec
t on the product. It is
the start of a common QA and QC plan


If it would be possible back wind the coil and rewind with 25 kg, change the angle more vertical has probably to be done imme
dia
tely. Nevertheless take
care not to change too many parameters at the same time or the picture will get foggy (I would change only one per time). Use

th
e time effectiveness

of
rapid proto to do this. Some years ago we could not do it, now you can. In key position multiply the rapid proto pieces to te
st
different options


In order to have stable winding condition for a series of coils differences in +/
-

0.1

0.15 mm on the curve part of the spacer
in contact of the cable shall
not affect the final results. On the other hand material thickness in prolongation to the wedges shall be in +/
-
0.01 0.02 range.

This dimension can be
easily measured by hand and will provide indication of the quality of the pieces.


Personally I would do 3D checking to understa
nd the production
capability of the rapid proto, but in series this shall be a statistical check



Stagger the transition wedge

end spacer


Complete qualification of the metallic rapid proto material but define before the criteria and do not make them unnecessarily

de
manding


Piece shall not be modified in production. This is for time effectiveness, reproducibility but also avoiding risks of electri
cal

defects. Flexible part could be a
tool, but here I have some concern on the possibility that they could harm the electrical insulation to be checked.


Investigate the use of a flexible end saddle as tooling for coil winding to help protect cable insulation and replace after c
uri
ng with a monolithic end
saddle.


Flexible end part shall be tested in HQ or LHQ before use


Straight part could be included in the spacer wedge during the design and initial proto phase. Then preparing the drawings fo
r r
eal coil, shift them to the
straight part wedges. This will also reduce costs


Use the program that you like the most, avoid calling one the BEND design and the other the ROXIE design. The key is the pers
on
using the tool, her/his
understanding of the problem, what she/he wants to do. For me they are equivalent.

Results matter. Nevertheless (see below)


When a design has been agreed the source file for the production and the drawings shall come only from one place and they sho
uld

be stored on a
common web site


If possible avoid superposition of the end(or beginning) of the last outer layer block and the last inner layer block. But do

no
t look only to the section.
Look at the developed heads to see if they cross/ align somewhere else


21/10/2013

G. Ambrosio and P. Ferracin

16