Detailed process of CNC precision machining

1. Machining principle error

The principle error of CNC machining is the error caused by the use of an approximate machining motion mode or an approximate tool profile. Because there is an error in the machining principle, it is called machining. Principle error. As long as the principle error is within the allowable range, this processing method is still feasible.

2. The geometric error of the machine tool

The manufacturing error, installation error and wear of the machine tool directly affect the machining accuracy of the workpiece . The main ones are the rotary motion of the machine tool spindle, the linear motion of the machine tool guide rail and the error of the machine tool transmission chain.

3. Tool manufacturing error and wear

The manufacturing error, installation error and wear of CNC machining tools all affect The machining accuracy of the workpiece. During the cutting process of the tool, the cutting edge and the cutter face have strong friction with the workpiece and chips, which causes the tool to wear. When the tool wear reaches a certain value, the surface roughness value of the workpiece increases, the color and shape of the chips change, and there is vibration. Tool wear will directly affect cutting productivity, machining quality and cost.

4. Fixture error

The fixture error of CNC machining includes positioning error, clamping error, fixture installation error and tool setting error. These errors are mainly related to the manufacturing and assembly accuracy of the fixture.

CNC machining accuracy cannot be perfect, as long as the error is controlled within a certain range, it is insignificant. Tool manufacturing errors and wear.

5. Positioning error

The positioning error mainly includes the reference misalignment error and the inaccurate error of positioning pair manufacturing. 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 positioning surface of the workpiece and the positioning element of the fixture together form the positioning pair. The large position change of the workpiece caused by the inaccurate manufacturing of the positioning pair and the matching gap between the positioning pairs is called positioning. Sub-manufacturing inaccuracy errors. The inaccurate manufacturing error of the positioning pair will only occur when the adjustment method is used for processing, and will not occur in the trial cutting method.

6. Adjustment error

In each process of machining, it is always necessary to adjust the process system in one way or another. Adjustment errors arise because the adjustment is impossible to be accurate. In the process system, the mutual positional accuracy of the workpiece and the tool on the machine tool is guaranteed by adjusting the machine tool, tool, fixture or workpiece. When the original precision of machine tools, tools, fixtures and workpiece blanks all meet the process requirements without considering dynamic factors, the adjustment error plays a decisive role in the machining error.

7. Measurement error

During CNC precision machining or measuring after machining, Because the measurement method, the accuracy of the measuring tool, the workpiece and the subjective and objective factors all directly affect the measurement accuracy.

The above seven machining errors can be avoided to a certain extent, so operators who need to perform machining can be more careful and careful about the six machining processes that are likely to cause machining errors. After inspection and verification of all aspects, machining operations are carried out, so that the influence of machining errors can be better reduced.