Interchangeability and Measurement Techniques - Tolerance Principles and Selection Methods

1.Tolerance principle

1.1独立性原则

For holes,DM=Dmin

For the axis,dm=dmax

 That is, the in vitro acting dimension of the shaft must be less than or equal to its largest cadaveric dimension150,The local solid size cannot be smaller than149.96

 2 Design with geometric precision

2.1 设计内容

（1）Geometric Tolerance feature item

（2）Tolerance principle：Independence principle and related requirements

（3）基准：

single benchmark,公共基准,and benchmark system

（4）公差值：Label the tolerance value,Tolerance values ​​are not noted

 Bearing assembly part,To put forward the requirements of cylindricity

 Sleeve or shaft parts are generally based on the center line

 Note that the geometric tolerance value is determined by looking up the table,But different projects have different main parameters,Roundness is measured in diameterdis the main parameter,Straightness in lengthLis the main parameter