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Studies in Precision Injection Molding of Carbon Fiber Reinforced LCP\A Practical Application to HDD Actuator E-block\
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Inoue, Toshio / Yoneta, Hiroyoshi / Hashimoto, Akio
This study is a part of an effort to develop precision injection molding of LCP. With the objection of replacing die-casted aluminum with injection molded LCP in an HDD actuator E-block application, modified design of experiment methods were used to investigate the significant factors involved both the injection machine operation process and the mold design. The preciseness was defined by the standard deviation (ƒÐ) of the arm tip heights of the E-block as measured on a laser scan micrometer, and values were compared with that of the die-casted aluminum E-block used in the HDD market. Among the machine process factors cut-off pressure was the most important one. Among the mold factors a cavity having a one-point gate located behind the carriage portion and a bridge connecting three arm tips, which functions as a slug-well and provides distortion resistance, gave the highest precision. For the purposes of high precision the mold geometry should permit molten LCP to flow with high symmetry. The value of the ƒÐ under the optimized process gave equal or better than that of aluminum E-block.
Key words: Precise injection molding / LCP / HDD actuator E-block / Standard deviation / Design of experiments method / Significant factors / Cut-off pressure / Slug-well / Warpage reduction / Symmetrical flow pattern