Tag Archive Precautions for CNC machining

At present, numerical control machining can not get rid of the fate of the industry in the modern era, and there will be some errors in the process of machining

1. Wrong processing principle

The main error of CNC machining is caused by approximate machining motion or approximate tool profile. Because of the error of machining principle, it is called machining principle error. As long as the main error is within the allowable range, this type of processing is still feasible.

2. Geometric error of machine tool

Machining error, installation error and wear during use directly affect the machining accuracy of the workpiece. It includes the rotation of the spindle, the linear motion of the guide rail and the error of the transmission chain.

3. Manufacturing error and wear of tools

The manufacturing error, installation error and wear of CNC machining tools in the process of machining will affect the machining accuracy of the workpiece. In the cutting process, the cutting edge, cutting surface, workpiece and chip produce strong friction, which leads to tool wear. When the tool wear reaches a certain value, the surface roughness of the workpiece increases, and the color and shape of the chip change. With the vibration, the tool wear will directly affect the cutting productivity, processing quality and cost.

4. Fixture error

CNC machining fixture error 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 is not perfect, as long as the error is controlled in a certain range, it will not have any significance. Tool manufacturing error and wear.

5. Positioning error

Positioning error mainly includes reference misalignment error and locator manufacturing error. When machining the workpiece on the machine tool, several geometric elements on the workpiece must be selected as the positioning reference. If the selected positioning reference and design basis are used (reference is used to determine the table on the part drawing)

Face size and location). If misalignment occurs, a reference misalignment error will occur. The positioning surface of the workpiece and the positioning part of the fixture form a positioning pair. Large displacement of workpiece caused by inaccurate positioning position and matching gap between positioning pairs is called positioning. Sub manufacturing inaccuracy

Wrong. The inaccuracy in positioning and manufacturing only occurs when the adjustment method is used, and will not occur in the trial cutting process.

6. Adjustment error

In each process, the process system is always adjusted in some way. Because the adjustment is impossible to be accurate, there is an adjustment error. In process

In the system, by adjusting the machine tool, cutter, fixture or workpiece, the mutual position accuracy of workpiece and cutter on the machine tool is ensured. When the original accuracy of machine tool, tool, fixture and workpiece blank meets the process requirements without considering the dynamic factors, the adjustment error plays a decisive role in the machining error.

7. Measurement error

When measuring parts during or after machining, the measurement accuracy is directly affected by the measurement method, measuring tool accuracy, workpiece and subjective and objective factors. To a certain extent, the above seven machining errors can be avoided, so the operators who need to process can test the six machining processes that may cause machining errors more carefully. After machining operation, the influence of machining error can be reduced better.

The above is for you to share the “CNC processing to pay special attention to a few places.”.

ken. tang@chengcg.com

1. The rotating speed of white steel knife shall not be too fast.

2. The copper cutter uses less white steel knife and more throwing knife or alloy knife.

3. When the workpiece is too high, it should be cut thick with different lengths of knives in layers.

4. Smooth the knife only when the margin is consistent. After the big knife is used for roughening, use the small knife to remove the surplus material.

5. The plane shall be processed with flat bottom knife and less spherical knife to reduce the processing time.

6. When the copper worker cleans the corner, first check the size of R on the corner, and then determine the size of the ball knife.

7. The four corners of the surface shall be level.

8. Where the slope is integer, it shall be processed with slope cutter, such as pipe position.

9. Before each working procedure, think about the surplus left after the previous working procedure, so as to avoid empty cutter or excessive machining.

10. Try to take a simple cutting path, such as contour, trenching, single side, less surround height.

11. When walking wcut, if you can walk finish, don’t walk rough.

12. When the shape of a smooth knife is smooth, it should be rough first, then fine. When the workpiece is too high, it should be smooth first, then the bottom.

13. Set tolerance reasonably to balance machining accuracy and computer calculation time. The tolerance is set to 1 / 5 of the allowance when opening rough, and to 0.01 when smoothing.

14. Do more processes to reduce the time of empty cutting. Think more and reduce the chance of mistakes. Do a little more auxiliary line auxiliary surface to improve the processing condition.

15. Establish a sense of responsibility and carefully check each parameter to avoid rework.

16. Be diligent in learning, good at thinking and continuous improvement.

Milling non plane, more ball knife, less end knife, do not be afraid to receive knife.

The small knife cleans the corner, the big knife is refined;

Don’t be afraid to mend the surface. Proper mending can improve the processing speed and beautify the processing effect.

High hardness of blank material: better reverse milling

Low hardness of blank material: good milling

Good accuracy, rigidity and finish machining of machine tool: it is more suitable for down milling and vice versa

It is strongly recommended to use down milling for the finishing of internal corners of parts.

Rough machining: better reverse milling, finish machining: better forward milling

Good toughness and low hardness of tool material: suitable for rough machining (machining with large amount of cutting)

Poor toughness and high hardness of tool material: suitable for finishing (machining with small cutting amount)