因其技术含量新、制造难度大，我国前些年一直依赖进口。
In past years, China has been relying on importing it since it features high technology and is quite difficult to manufacture.
磁极是汽车发电机上的关键零件，其形状复杂，尺寸精度和内在质量要求比较高，制造难度大。
Alternate pole, which has complex shape and strict limit in its size and quality, is the key part in the automobile generator, so it is difficult to produce.
多工位级进模精度要求高，结构复杂，传统的串行开发存在着制造难度大、生产周期长的缺点。
Because of the high precession and complicated construction requirements, the multi-stationed progressive die is hard to process with the traditional serial development besides a long production term.
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