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The Causes Of Machining Errors In CNC Machining Centers

CNC machining center is a kind of high-precision, high-efficiency automatic metal machining equipment, equipped with multi-station turrets or dynamic turrets, which can process linear cylinders, inclined cylinders, arcs and various complex workpieces such as threads, grooves, and worms.

With linear interpolation, arc interpolation and other compensation functions, it has played a good economic effect in the mass production of complex parts. However, any problems in the control system, drive system, and electrical and mechanical systems of the plant can lead to error problems. In the following guide, we briefly describe the causes and solutions for errors in CNC machining.

What are the reasons for CNC machining center errors and how to solve them

  • ① In high-speed machining, the CNC system may have acceleration and deceleration errors and servo system lag errors.
  • ②Due to the inertia of the control system, the drive system and the electromechanical system of the controlled object, dynamic errors such as shock, vibration, overtravel, and out-of-step will occur when the acceleration is large.
  • ③In three-axis CNC vertical milling, the machining error consists of two factors: linear approximation error and normal vector rotation error;
  • ④ The machining error is related to the normal curvature of the machined surface, the tool radius and the interpolation length, and is proportional to the square of the interpolation length.
  • ⑤Programming, tool selection and human factors may also lead to abnormal machining accuracy.
  • ⑥ The rotation error of the normal vector is caused by the rotation of the normal vector of the machining surface along the direction of the interpolation line, which is proportional to the size of the tool radius.
  • ⑦ Precision error caused by the influence of tool material and cutting oil performance.

The solution to the error of CNC machining center

  • ①The automatic speed increase and decrease of the numerical control system is automatically realized by the software function of the numerical control system. The basic requirement is that the selected acceleration and deceleration law must ensure the trajectory accuracy and position accuracy, and ensure that the acceleration and deceleration process is fast, stable and stable. At the same time, the control algorithm should be as simple as possible and easy to implement by computer.
  • ② For the convex surface, the normal vector rotation error can be compensated by modifying the tool center position, while for the concave surface, no compensation is required; when the system does not have an automatic compensation function, the method of reducing the tool radius is used to reduce the error.
  • ③ The linear approximation error is determined by the interpolation chord length, which is related to the interpolation cycle of the CNC system and the tool feed rate. The linear approximation error can be controlled by selecting a CNC system with a smaller interpolation cycle or reducing the feed rate.
  • ④ The residual height error of the cutting line is the main factor affecting the surface roughness of the workpiece in the surface machining. The error can be controlled by selecting reasonable cutting line width parameters.
  • ⑤ The tool material and cutting oil of the CNC center directly affect the wear degree of the tool, and the tool that wears quickly will cause a larger error to the workpiece. Choosing the appropriate tool and cutting oil for different processes can help improve the accuracy of the workpiece.

The above is the reason for the error of the CNC machining center. Only by analyzing the mechanism of the error, can targeted measures be taken to effectively improve the quality of the workpiece.