On a lathe, the rotational motion of the workpiece and the linear or curvilinear motion of the tool are used to change the shape and size of the blank and machine it to meet the requirements of the drawing.
Ordinary machine tools are increasingly difficult to meet the needs of processing precision parts. At the same time, the price of CNC machine tools is decreasing due to the improvement of production level. CNC precision parts machining mainly includes ultra-precision turning, mirror grinding and grinding, etc.
CNC precision parts machining is the primary premise is the accuracy of its process benchmark, the benchmark on the mechanical drawings are expressed in capital letters A, B, C, D, etc. with a specific benchmark symbol with a circle. When the benchmark symbol is aligned with the face and the face of the extension line or the face of the dimensional limits, said to be the face of the benchmark. When the datum symbol is aligned with a dimension line, it means that the centerline of the solid marked with that dimension is the datum. The process precision mentioned for you is a more general point.
Assembly datum, refers to the precision used to determine the position of the part in the component or product during assembly. Measurement datum refers to the standard used to measure the size and position of the machined surface when the part is inspected. Positioning datum refers to the datum used to position the workpiece in the machine tool or fixture during machining.
