通常在进行铰孔加工时,所用的夹具精度要求较高.如导向件的精度和垂直度,定位件的位置精度,要求都较严格.但在设备精度、工具及刀具制造水平较差的情况下,是不容易获得较高精度的.因而在某些地方不使用夹具,而采用手工操作来补偿这个缺点.但它的加工范围要受到一定的限制,同时它也需要技术较高和操作熟练的操作工人操作,而且操作不安全,容易造成工伤事故.所以一般不使用它. Usually in the reaming process, the fixture used in the high precision.If the accuracy and verticality of the guide, the positioning of the positioning accuracy, the more stringent requirements.However, the accuracy of the equipment, tools and tools in the case of poor manufacturing level , It is not easy to obtain higher accuracy, so in some places do not use the fixture, but the use of manual operation to compensate for this shortcoming, but its processing range to be subject to certain restrictions, it also requires high technology and skilled operation The operation of workers, but also unsafe operation, easy to cause work-related accidents, so generally do not use it.