大连精密零部件加工精度是加工后零件外貌的实际尺寸、形状、位置三种几何参数与图纸要求的理想几何参数的切合水平。理想的几何参数，对尺寸而言，就是平均尺寸；对外貌几何形状而言，就是绝对的圆、圆柱、平面、锥面和直线等；对外貌之间的相互位置而言，就是绝对的平行、笔直、同轴、对称等。零件实际几何参数与理想几何参数的偏离数值称为加工误差。

尺寸精度

指加工后零件的实际尺寸与零件尺寸的公差带中心的相切合水平。

形状精度

指加工后的零件外貌的实际几何形状与理想的几何形状的相切合水平。

位置精度

指加工后零件有关外貌之间的实际位置精度差别。

相互关系

通常在设计机械零件及划定零件加工精度时，应注意将形状误差控制在位置公差内，位置误差又应小于尺寸公差。即精密零件或零件重要外貌，其形状精度要求应高于位置精度要求，位置精度要求应高于尺寸精度要求。

The machining accuracy of precision components in Dalian refers to the degree of conformity between the actual dimensions, shape, and position of the surface of the processed parts and the ideal geometric parameters required by the drawings. The ideal geometric parameters, in terms of size, are the average size; For surface geometry, it refers to absolute circles, cylinders, planes, cones, and straight lines, etc; For the mutual position between surfaces, it refers to absolute parallelism, perpendicularity, coaxiality, symmetry, etc. The deviation between the actual geometric parameters of the part and the ideal geometric parameters is called machining error.

dimensional accuracy 

The degree of conformity between the actual size of the processed part and the center of the tolerance zone of the part size. Shape accuracy

The degree of conformity between the actual geometric shape of the machined part surface and the ideal geometric shape.

Position accuracy

The actual positional accuracy difference between the surfaces of the processed parts.

interrelation

Usually, when designing machine parts and specifying the machining accuracy of parts, attention should be paid to controlling the shape error within the positional tolerance, and the positional error should be less than the dimensional tolerance. The shape accuracy requirements of precision parts or important surfaces of parts should be higher than the positional accuracy requirements, and the positional accuracy requirements should be higher than the dimensional accuracy requirements.