Detailed process of CNC precision machining

1. Machining principle error

The principle error of CNC precision machining is the error caused by the use of an approximate machining motion or an approximate tool profile. It is called processing principle error. As long as the principle error is within the allowable range, this processing method is still feasible.

2. 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. Manufacturing error and wear of the tool

The manufacturing error, installation error and wear of the tool processed by CNC precision machining 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 precision 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.

The precision of CNC precision machining 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 the workpiece is processed on the machine tool, several geometric elements on the workpiece must be selected as the positioning reference during processing. If the selected positioning reference does not coincide with the design reference, a reference misalignment error will occur, and the workpiece positioning surface and the fixture positioning element The positioning pair is formed together. The large position variation of the workpiece caused by the inaccurate manufacturing of the positioning pair and the matching gap between the positioning pairs is called the manufacturing inaccuracy error of the positioning pair. 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.