1. The production error of the machine tool. The manufacturing errors of machine tools mainly include spindle rotation errors, guide rail errors and transmission chain errors. Spindle rotation error refers to the variation of the actual rotation axis of the spindle relative to its uniform rotation axis at each moment, which will directly affect the accuracy of the workpiece to be processed. The main reasons for the main shaft rotation error are the coaxiality error of the main shaft, the error of the bearing itself, the coaxiality error between the bearings, and the winding of the main shaft. The guide rail is the benchmark for determining the relative orientation of each machine tool component on the machine tool, and it is also the benchmark for the movement of the machine tool. The manufacturing error of the guide rail itself, the uneven wear of the guide rail and the quality of the device are the important factors for the formation of the guide rail error. Transmission chain error refers to the error of relative motion between the transmission elements at the beginning and end of the transmission chain. It is caused by the production and assembly errors of each component in the transmission chain, as well as the wear and tear during use.

2. A few errors in the tool. Any tool will inevitably wear during the cutting process, which will cause the size and shape of the workpiece to change. The influence of tool geometry errors on machining errors varies with the type of tool: when a fixed-scale tool is selected for machining, the tool manufacturing error will directly affect the machining accuracy of the workpiece; for general tools (such as turning tools, etc.), its manufacturing errors No direct effect on machining errors.

3. A few errors in the fixture. The effect of the fixture is to make the workpiece equivalent to the tool and the machine tool to have the correct orientation, so the geometric error of the fixture has a great influence on the machining error (especially the orientation error).

4. Positioning error. The positioning errors mainly include reference misalignment errors and inaccurate positioning errors. When processing the workpiece on the machine tool, several geometric elements on the workpiece must be selected as the positioning datum during processing. ) does not coincide, a reference misalignment error will occur.

The workpiece positioning surface and the fixture positioning element together form the positioning pair, because the inaccurate manufacturing of the positioning pair and the maximum azimuth variation of the workpiece caused by the cooperative gap between the positioning pairs is called the inaccurate manufacturing error of the positioning pair. The inaccurate error of positioning pair production will only occur when the adjustment method is selected for processing, and will not occur in the trial cutting method.

5. Errors caused by force and deformation of the process system. Workpiece stiffness: In the process system, if the workpiece stiffness is relatively low compared to machine tools, tools, and fixtures, under the effect of cutting force, the deformation of the workpiece caused by the lack of stiffness will have a greater impact on machining errors.