1. Design basis

The axis is the design basis of the inner hole, one end surface is the design basis of the other end surface and the stepped surface, and the axis of the inner surface is the design basis of the outer surface

2. Process benchmark

Process benchmarks are the benchmarks used in the process of manufacturing parts and installing machines.

(1) Positioning datum refers to the datum used for positioning the workpiece in the machine tool or fixture during processing.

(2) Measuring benchmark refers to the benchmark used to measure the size and position of the machined surface during part inspection.

(3) Assembly datum refers to the datum used to determine the position of the part in the component or product during assembly.