Flatness recovery technique May 30, 2008 T. Higo and T. Takatomi

Flatness control We made T18_VG2.4_disk #1, #2 ( also #3 and #4) by outside company, Morikawa. The machine, Seibu-denki, is precision lathe but the alignment of the axis is intentionally slanted. A study was done to make the end surface to be adjusted by a NC movement of making a cone shape with its minimum step of 0.1 micron. It seems we can control the surface well if we can accept the minimum step of the NC control. How do you think this cure? If you accept it, we do not need to make the final machining at KEK. If not, we do the final cut at KEK but it gives us much work load. The cutting for the damping waveguide may simply makes us do the final cut at KEK. It will be determined at the preparation stage of the fabrication. I worry that some time is needed even for us because many years has passed since we made a so-called butterfly cell for DDS3 etc. Please give us comments.

CLIC_vg1-A Flatness measurement A-No.00 cupside A-No.00 diskside 両面とも１ μ ｍ程度中ベコになっている。 これは加工機の初期設定によるものと考えられる ばらつきは ±0.5 μ ｍ程度 １ μ ｍ中高にすることで平面度 ±0.5 μ ｍが可能

Study condition in Japanese 試験、測定：株式会社森川製作所 試験内容： 加工プログラムにより中高に加工した場合の平面の評価 （ 0μ ｍ狙い、 0.2 μ ｍ中高狙い、 0.5 μ ｍ中高狙い） 加工条件： – 加工機：西部電機旋盤ＳＮＣ－３５ＨＰ（最小設定単位：０．１ μ ｍ） – ワーク：無酸素銅（アニール無し） φ55×20 – 加工条件： 工具：単結晶ダイヤモンドバイト 加工液：トナオイルＳ ( 昭和シェル石油 ) チャック：三爪チャック（チャック圧 0.07MPa) 回転数： 500min-1 切削速度： 0.015mm/rev 切り込み量 :0.005mm

平面 ０ μ ｍ狙い

平面 ０.2μ ｍ中高狙い

平面 ０.5μ ｍ中高狙い

0.5μ ｍ狙い平面写真 目視では段差は見られない

Result and discussion The shape due to three nails for chucking were found. We assume that this is due to the rough machining, though we should confirm. Concave shape was confirmed without NC correction. The better flatness this time is due to using a different machine, though of the same series. – 0.5 micron: CLIC_VG1=SNC-20HP (Seibu-denki) – 0.2 micron: Present test=SNC-35HP (Seibu-denki) The case of 0.5 micron target becomes 0.5 micron convex, as designed. The step of NC correction is 0.1 micron. I think the 0.1 micron step is tolerable. KEK or SLAC should check this conclusion experimentally. If no voids remains after diffusion bonding, it should be OK. If OK, do we apply convex correction by say 0.2 microns?