Factors affecting the machining location accuracy and improvement measures.

1. Machine tool error. Position error between tool cutting forming surface and clamping surface of machine tool; The relationship between the forming motion locus not correct, cause the position error between the machined surfaces in the same installation; The thermal deformation and mechanical deformation of machine tools destroy the geometric accuracy of machine tools, resulting in a Machining error between the machined surfaces or between the machined surface and the positioning datum. Improvement measures: to improve the geometric accuracy of machine tools; to reduce or compensate for thermal deformation of machine tools; to reduce or compensate the force deformation of machine tools.

2. Fixture manufacturing error and fixture installation error, directly affects the positional accuracy between the machined surface and the positioning datum surface. Improve measures: improve fixture manufacturing accuracy, improve fixture installation accuracy.

3. Alignment error. The error in the installation of the workpiece by using the alignment method (line alignment or direct alignment), directly affects the positional accuracy between the machined surface and the positioning datum surface. Improve measures: improve the accuracy of alignment base level; improve the level of alignment operation; adopt the alignment method and tool to adapt to the requirement of machining accuracy.

4. The working positioning datum does not coincide with the design datum, and directly affects the position accuracy between the machined surface and the design datum plane. Improvement measures: use the design benchmark as the positioning benchmark; improve the position accuracy between the design basis and the positioning datum.

5. Workpiece positioning datum error. Affect the position accuracy between the machined surface and the positioning datum; The positional accuracy between the machined surfaces is affected by multiple mounting processes. Improvement measures: to improve the accuracy of the datum plane; to use the expansion mandrel or to apply external force in the fixed direction to ensure the fixed edge contact, and other methods to reduce the error influence.

6. Benchmark conversion. In the multi process machining, the positioning datum conversion will increase the position error between the machined suiface in different processes or different installations. Improvement measures: try to adopt a unified fine benchmark in order to avoid the datum conversion; try to adopt the principle of process centralization; improve the accuracy of the positioning datum surface itself and the positional accuracy between the datum surface.

7. Technical level of workers' operation. Improvement measures: improve workers' operation skill level.