1. Error in processing principle
The principle error of CNC machining is the error caused by adopting the approximate machining motion mode or the approximate tool contour. Because there is an error in the machining principle, it is called a machining principle error. As long as the principle error is within the allowable range, this processing method is still feasible.
2. Geometric error of machine tool
The manufacturing error, installation error and wear of the machine tool directly affect the machining accuracy of the workpiece. Among them are the machine tool spindle rotary motion, machine tool guide rail linear motion and machine tool transmission chain error.
3. Manufacturing error and wear of the tool
The manufacturing error, installation error and wear in use of CNC machining tools all affect the machining accuracy of the workpiece. During the cutting process of the tool, the cutting edge, the cutting surface and the workpiece and the chip generate strong friction, 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 chip change, and it is accompanied by vibration. Tool wear will directly affect cutting productivity, machining quality and cost.
4. Fixture error
The errors of CNC machining fixtures include positioning errors, clamping errors, fixture installation errors and tool setting errors. 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 will not matter. Tool manufacturing errors and wear.
5. Positioning error
Positioning errors mainly include reference misalignment errors and positioning pair manufacturing inaccurate errors. When processing the workpiece on the machine tool, several geometric elements on the workpiece must be selected as the positioning reference during processing. If the selected positioning reference and design reference (the reference used to determine a certain surface size and position on the part drawing) ) If there is no coincidence, there will be a reference misalignment error. The workpiece positioning surface and the fixture positioning element together form a positioning pair. Due to the inaccurate manufacturing of the positioning pair and the large clearance of the workpiece caused by the matching gap between the positioning pair, it is called positioning. Inaccurate errors in sub-manufacturing. Inaccurate errors in positioning pair manufacturing will only occur when the adjustment method is used for processing, and will not occur during trial cutting processing.
6. Adjustment error
In each process of mechanical processing, the process system must always be adjusted in one way or another. Since the adjustment is impossible to be accurate, an adjustment error occurs. In the process system, the mutual position accuracy of the workpiece and tool on the machine tool is guaranteed by adjusting the machine tool, tool, fixture or workpiece. When the original accuracy of machine tools, tools, fixtures and workpiece blanks meets the process requirements without considering dynamic factors, adjustment errors play a decisive role in machining errors.
7. Measurement error
When the parts are measured during or after processing, the measurement accuracy is directly affected by the measurement method, the accuracy of the measuring tool, and the workpiece and subjective and objective factors.
The above seven machining errors can be avoided to a certain extent, so operators who need to perform machining can more carefully and carefully detect and verify the six machining processes that are prone to machining errors during processing. After that, the machining operation is carried out, so that the influence caused by the machining error can be better reduced.
