Quadrant Fabrication Study KEK Toshikazu TAKATOMI Yuichi WATANABE 2nd Collaboration Meeting on X-band Accelerator Structure Design and Test-Program 13-15 May 2008

Test Quadrant Structure This structure is made for four parts. The cell size is individually different for accelerating gradient. It needs the milling for three-dimensional shape. Theoretically exact profile tolerance is under 5 μｍ. Material is Zr-Cu(C150). The nominal dimensions　are not visible on the drawing, So We must extract from 3D model. All edges of reference surfaces zone A and B have a radius of 0.05±0.01mm. Don’t have the burrs.

The drawing of test Quadrant Structure Beam Coupler Cavity Coupler Reference surface Flatness ：under 5μｍ Square ness ： under 5μｍ Cavity （Zone A） Theoretically exact profile tolerance ： 5 μｍ Surface roughness ：Ra0.1

Issues in processing To keep in straight The bending must be under 5μm for needs straight of beam line. Material is Zr-Cu(C150:φ65×300). It can't have heat anneal. We have to get the processing which doesn't bend. Dimension and theoretically exact profile need high precision Error factor is variations in temperature and in machine motion. We have to study for error factor. Quality of Surface roughness We have to get under Ra0.1 in surface roughness. but, it gets difficult at ball-nosed end mills. We have to study for the processing.

Points of Fabrication Fabrication was the 5-axis precision machine that is controlled with constant temperature at 23±0.5 ℃ degrees. CAM data was made to change in 23 ℃ degrees temperature. We studied to find the best processing. Alignment of the machine and shape of the tools was measured to keep high precision. It is processed four times to repair bend.

Flatness measurement of references D C B A A B C D 1 2 3 Cavity 4 5 6 n Non fixation Cavity Non fixation Reference surface got at under 6 μｍ.(under 4 μｍ at cavity) Reference Ａ Reference B Measurement point

Dimensions of Beam Direction CT ：Disk thickness CW ：Cell width It had Inclination about 0.02mm Each distance was ±0.005mm

Dimensions of depth data (Cell and Iris) Cells Iris Each distance was -0.01mm±0.004mm

Profile measurement (Beam direction) Beam direction No. 18cells Tolerance is ±2.5μm. Best fit result It was almost within the tolerance.

Profile measurement (cross direction) Cross direction of No.18cell Tolerance is ±2.5μm. Best fit result It’s OK! Cross direction of No.18iris Tolerance is ±2.5μm. Best fit result It had error about 5μm.

Surface roughness It is limited by our process now?? A-1 ： Ra0.20 B-1 ： Ra0.20 B-2 ： Ra0.33 C-1 ： Ra0.11 C-2 ： Ra0.13 D-1 ： Ra0.15 D-2 ： Ra0.16 Roughness in cavity was under Ra0.4 Tool speed have to move very slowly to get high quality by ball-nosed end mills. but, it have very long process times. then ,it occur of another error factor. It is limited by our process now??

Inspection of edges This is good! Burr was not seen. Side A input output Iris_0-1_sideA Iris_11-12_sideA Iris_18-19_sideA Iris_5-6_sideA Burr was not seen. It had edges of chamfering at 0.05mm. This is good!

Summary Reference surface got at under 6 μｍ. Cavity was under 4 μｍ. Dimensions of beam direction had inclination about 0.02mm. It was gotten variations in temperature. We had to study. Profile measurement at beam direction was almost in the tolerance. Roughness in cavity was under Ra0.4 In the future, we will reach the goal based on those results. Acknowledgment We would like to express my gratitude to U-CORPORATION Co.,Ltd and Hitachi,Ltd about fabrication study.