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: http://www.apo.nmsu.edu/Telescopes/SDSS/eng.papers/19930517_ferrule_wear/19930517_ferrule_wear.html
Дата изменения: Tue May 19 04:55:56 1998 Дата индексирования: Sun Apr 10 08:44:28 2016 Кодировка: Поисковые слова: jet |
Russell Owen
Ferrules are typically made of either stainless steel or ceramic. Ceramic ferrules are very high precision and hard enough that wear is not a concern. However, they are more expensive than stainless steel and may crack, resulting in a defect that could be very difficult to find yet cause erratic loss of throughput. Also, ceramic ferrules may be difficult to find with the required fiber hole size. Stainless steel ferrules offer lower precision (which will lose us approximately 1/2 to 1% light compared to ceramic), but they are relatively inexpensive, readily available with the hole diameter we require, and immune to cracking. The big question about stainless steel ferrules is whether they are hard enough to stand up to repeated plugging; the tests reported on below indicate that the answer is "yes".
The ferrule and holes were inspected under a 35 power stereo microscope. The spiral grooves left by the tools were clearly visible, but both the ferrule and all inspected holes looked excellentЁvery round and clean. After the plugging operation the ferrule was visibly worn; but the tooling marks were still quite visible under the wear marks. Hence the wear was not very deep. The ferrule also had many new fine axial scratches, but so fine and so widely distributed as to have no possible effect. The holes (each of which had been plugged twice by the ferrule) had one or two narrow roughly axial bands of wear, but they covered less than 1/10 of the area of the hole and appeared to be so shallow as to be merely cosmetic.
Figure 1 shows the change in diameter of the ferrule as a function of the number of holes plugged. The results agree with the visual inspection: the ferrule exhibits some wear, but not enough to cause concern. Each ferrule will be used to plug approximately 300 holes, at which point the ferrule's diameter will be reduced by approximately 0.06 mils. This translates to a tilt of 0.5 mrad, which will have no measurable effect on throughput. Extrapolating the data, we would have to plug well over 5000 holes before reaching 1 mil of wear.
These tests show that stainless steel ferrules should serve us quite well, and that using aluminum for plug plates is also an excellent choice.