1. L/R Coil Asymmetry Coil Fabrication Working Group Trey Holik Wednesday, June 3 rd 2015

2. 2 Coil L/R Asymmetry Coils 1,3, and 5 were R&I at BNL; Coil 2 was at FNAL There seems to be some systematic shape… but from where? From what? https://plone4.fnal.gov/P1/USLARP/MagnetRD/qxf/drawings/Reaction_Im pregnation/ https://plone4.fnal.gov/P1/USLARP/MagnetRD/qxf/drawings/Reaction_Im pregnation/ After Centering Coil OD and keyway, L-R Asymmetry = L (T side) midplane ̶ R (NT side) midplane

3. Uniform Over/Under can be accommodated during magnet assembly. Asymmetry and non-uniformity (along length) is impractical to accommodate. Asymmetry can drive excessive/insufficient preload. L-R asymmetry of 200 um -> Δl ~ 100 um, l ~ 50 mm Δl / l ~ 0.2% -> Irreversible current degradation E ~ 45 GPa, E(Δl/l) ~ 90 MPa Asymmetry can generate unallowed harmonics To what extent??? 3 Why Important?

4. 3 main R&I surfaces for alignment Modified Form block hole size and location Pole keyway alignment Form and mandrel block interface 4 Coil fab alignment Tooling Look at Design/Tolerance and tooling QC W & C alignment is with Pole dowel pins and Mandrel

5. 5 R & I Tooling (By Design) Mandrel block can shift L or R by 10 um relative to the base plate (Only contributes to coil linearity and NOT asymmetry) Form block can shift L or R by 10 um relative to the mandrel block -> Maximum L/R asymmetry is 20 um Pin Pin hole Form block Pole Mandrel block Base plate

6. 6 Max Tolerance 0.015 mm from hole size -> Maximum L/R asymmetry is 578 um or nearly 23 mils!!! 0.050 mm from hole location 0.015 mm from pin size 0.050 mm from form block radius 0.019 mm from form and mandrel block radius centers (0.110 mm if rigid assembly -> Assembly wouldn’t close.) 0.020 mm from pole keyway size (0.050 mm) from pole edges (only effects turn asymmetry) 0.030 mm from SS outer shim 0.050 mm from mandrel block radius 0.289 mm total 0.030 mm from mandrel block coil midplane 0.010 mm from intrinsic design Pin Pin hole Form block Pole Mandrel block Base plate

7. 7 Mid of Tol. (Best EDM Prac.) 0.008 mm from hole size -> Maximum L/R asymmetry is 172 um or nearly 7 mils!!! 0.008 mm from pin size 0.025 mm from form block radius 0.010 mm from pole keyway size 0.025 mm from mandrel block radius 0.086 mm total 0.010 mm from intrinsic design Maximum L/R asymmetry measured is roughly 210 um or 8 mils!!! Pin Pin hole Form block Pole Mandrel block Base plate

8. Based on the number of crucial dimensions/surfaces the asymmetry observed is very good. If the EDM operator centers the drawing tolerance, then ±170 um of movement around perfect symmetry is expected. This is consistent with ± 210 um of observed asymmetry. Likely that the tooling isn’t driving but is allowing the asymmetry There are two steps to verify this assumption: 1.Ship coil 4 to BNL. Change the 4 modified form block positions, impregnate, and analyze coil CMM changes. 2.CMM the 4 modified form blocks to possibly correlate with coil asymmetry. What does tooling CMM data have to say? 8 Observations

9. Alignment hole not CMMed. 5 of 24 blocks were CMMed 9 Modified Form Block CMM Rejected +0.050 - 0.0 mm

10. 10 Mandrel Block CMM 27 blocks were CMMed ±0.030 mm +0.0 - 0.050 mm +0.0 - 0.050 mm

11. 11 Does R&I tooling effect L-R? For Coil 4, use BNL Impreg tooling Mod. Form block 3 1, 2 4 ??? For Coil 6, continue with FNAL tooling Mod. Form block 2 3, fab delay ??? Pin 1 2 3 4

12. The R&I critical surfaces are numerous and makes CMM data difficult to conglomerate. Reducing R&I tolerance is impractical and will minimally decrease the allowed asymmetry. CMM on assemblies can reduce the number of critical surfaces and simplify interpretation The form and mandrel block radii and the modified form block pin hole are the largest sources of R&I clearance. The clearance might be reduced by the following: CMM all Mandrel blocks as installed on the Base plate CMM all Form blocks as installed with side bars and top plate Design custom Coil OD Mylar thickness to perfectly center the Mandrel and Form blocks based on assembly CMM. Check with Fuji paper. Re-machine the Modified Form blocks to perfectly size and locate the pin hole relative to the assembly. 12 How to Reduce the Asymmetry?

13. 13 Assembly CMM CMM Red surfaces Customize SS/Mylar shim package based on form and mandrel block radii and Fuji paper. Customize modified form block holes based on form block radius and location

14. 14 Assembly CMM If the form block radius is too large then we may need to CMM the side channels while the mandrel blocks are compressed. PRESSURE To ensure that the form and mandrel blocks are in intimate contact it is possible to add symmetric shims between the base plate and mandrel blocks to raise the mandrel blocks.