How to Improve the Machining Accuracy of Workpiece in CNC Milling?

What are the methods to improve the machining accuracy of workpieces in cnc milling?

 

 

Adjust the processing system

 

• The trial cutting method is adjusted by trial cutting - measuring the size - adjusting the cutting depth of the tool - walking Cutting - re-cutting, and so on until the required size is reached. This method has low production efficiency and is mainly used for single-piece and small-batch production.

 

• The adjustment method obtains the required size by adjusting the relative positions of the machine tool, fixture, workpiece, and cutter in advance. This method has high productivity and is mainly used for mass production.

 

Reduce machine error

 

• The rotation accuracy of the bearing shall be improved:

 

① Select high-precision rolling bearings;

② Adopt high-precision multi-oil wedge dynamic pressure bearing;

③ Adopt high-precision hydrostatic bearing

 

• Improve the accuracy of the accessories with bearings:

 

① Improve the machining accuracy of the box support hole and the main shaft journal;

② Improve the machining accuracy of the mating surface with the bearing;

③ Measure and adjust the radial runout range of corresponding parts to compensate or cancel errors.

 

• Properly pre-tighten the rolling bearing:

 

① Clearance can be eliminated;

② Increase bearing stiffness;

③ Homogenize the rolling element error.

 

• The spindle rotation accuracy is not reflected on the workpiece

 

Reduce transmission error of transmission chain

 

• The number of transmission parts is small, the transmission chain is short, and the transmission accuracy is high;

 

• Adopting speed reduction transmission is an important principle to ensure transmission accuracy, and the closer to the end of the transmission pair, the smaller its transmission ratio should be;

 

• The accuracy of end parts shall be higher than that of other transmission parts.

 

Reduce tool wear

 

• Before the tool size wear reaches the sharp wear stage, the tool must be reground

 

• Select special cutting oil for full lubrication

 

• The cutter material shall meet the process requirements

 

Reduce the stress and deformation of the processing system

 

• Improve the stiffness of the system, especially the stiffness of weak links in the processing system;

 

• Reduce load and its variation

 

Reduce thermal deformation of process system

 

• Reduce heat generation of heat source and isolate heat source

 

• Equilibrium temperature field

 

• Adopt reasonable machine tool component structure and assembly benchmark

 

• Accelerate to achieve heat transfer equilibrium

 

• Control ambient temperature

 

Reduce residual stress

 

• Add heat treatment process to eliminate internal stress;

 

• Reasonably arrange the process.

 

The above is the method to reduce the error of machining the workpiece in cnc milling. Reasonable arrangement of the process can effectively improve the accuracy of the workpiece.