Nissei Developed A Optical Ferrule Production System
Nissei Plastic Industrial Co., Ltd. has recently developed a new system, the "Optical Ferrule Production System," which produces ferrules of high quality and high accuracy. Ferrules are the main parts of connectors for optical communications use. Nissei opened an explanatory meeting with a display using panels and a videotape of this system at the "OFC 2002" exhibition held in Anaheim, U.S.A. from March 19th through the 21st of this year. The total system was highly appreciated by the visitors, and some of them wished to observe the system actually. Since the company received very favorable public estimation, it will start overseas sales of the system. Further, the "OFC (Optical Fiber Communications Conference and Exhibit) 2002" is the largest exhibition of optical communication in the world. This time, more than about 1,300 related companies exhibited their products. This "Optical Ferrule Production System" is composed of molding materials, a mold, an automatic arraying equipment installed with a function of product taking-out/gate-cutting, a degreasing furnace, a sintering furnace and a abrasive device, besides the company's electric injection molding machine. This automatic production line integrally processes zirconia as a main material, a kind of ceramics, into semi-final products (blanks) before final processing of ferrules. Ferrules are ultra high-precision parts made of zirconia which fix optical fibers in an optical connector for positioning with a precision of a submicron level. The connection of optical fibers is conducted by means of accurately joining optical fibers each other in a divided sleeve through inserting optical fibers into a part of a ferrule with an inner diameter of Ø0.125, and bonding/fixing them. It is necessary to make the eccentricity, between centers of outer diameter of Ø2.499 part and inner diameter of Ø0.125 part of a ferrule, to be 0.0007 mm or less, in order to hold down the loss to a minimum at the time of connection. For molded products, therefore, it is necessary to control the eccentricity between an outer diameter and an inner diameter of a blank to be 0.015 mm or less, and also to attain its bending against the central part to be 0.015 mm or less. Compared with ordinary injection molded products, one or two digit higher dimensional accuracy is required. This system aims to manufacture products with the following standards: Concentricity: 10 micrometer or less in blank. Single mode yield: to be more than 85%. Nissei has closely cooperated with each related equipment maker including raw material manufacturers for the development of this molding system. The company has established comprehensive technologies for improving the yield of molding materials, stabilizing quality, stable molding and making high-precision molds. The molding of ferrules is conducted in the same way as ordinary plastics molding. However, since molding materials have no Barus effect (This means that when viscoelasticity fluid flows out from a capillary, the diameter of an outflow material generally becomes larger than the diameter of the capillary.) at all, different from ordinary plastics, so the setting up of molding conditions is difficult. Moreover, it is necessary to pay attention not to break molded products because the diameter of a fine hole at the central part of molded products is very fine such as 140 micrometer. Based on the company's molding machine for fine-pitch connector dedicated electric molding machines have been developed. There are two models of machines with a mold clamping force of 20 tons (196 kN) and 40 tons (392 kN). For these molding machines, various devices as a ferrules molding have been contrived as follows: In regard to the injection mechanism;
In regard to the mold clamping mechanism;
This system uses a special purpose compound as a molding material which excels in moldability and degreasing power. It is a mixture of zirconia, thermoplastic resins and other ingredients. After completion of injection molding, a traversing type take-out unit unloads products, and after gate cutting, products are arrayed on a setter. Molded products arrayed are put in a degreasing furnace to pyrolyze the binder component, after that degreased products are sintered. After completion of sintering, both ends of sintered products are polished by a polisher and the overall length is determined. Thus blanks are completed.
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